• Author / Uploaded
• Luis Perez

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General MsTower is a specialized program that assists in the analysis and checking of latticed steel communication and power transmission towers and guyed masts. MsTower contains options for defining the geometry, loading, analysis, plotting of input, results, and member checking. Loading may be computed in accordance with: BS 8100:Part 1 1986. BS 8100:Part 4 1995 CP3 Chapter 5 AS 3995-1994 Malaysian Electricity Supply Regulations 1990. EIA/TIA-222-F-1996. Member capacities may be checked against the requirements of: BS 8100:Part 3 (DD133:1986) BS 449 AS 3995-1994. ASCE 10-90 1991 EIA/TIA-222-F-1996 Towers, which may be of three or four sides, are assembled by combining a series of standard face, plan, hip and cross-arm panels. The tower profile is defined by giving the height of individual panels and the width at "bend" points. All other widths are obtained by interpolation. The range of standard panels is being regularly increased with over 100 different panel types available at present. A number of the standard panels are parameterised so that the user may readily modify the configuration. If a suitable standard panel is not available the system accepts "user defined panels" (UDP). While these require much more data than a standard panel, they allow the system to be used for virtually any tower configuration. A UDP may consist of anything from a few members that make up half a face panel to a full three-dimensional section of the tower; the program carries out all the necessary replications and geometric transformations. The result of the tower building process is a complete MsTower data file, Job.MST, where "job" is the MsTower job name. The loading module of MsTower computes loads due to self-weight, ice, and wind on the tower. As well as computing wind loads on the bare tower the program is able to take account of a wide range of ancillary items found on communication towers. Ancillaries are classified into the following categories: Linear ancillaries, normally within the body of the tower and consisting of items such as ladders, feeders and wave-guides.

Face ancillaries, attached to the face of the tower and consisting of small items such as minor antennae, gusset plates and platforms. Large ancillaries, mounted out from the face of the tower and consisting of large dishes whose wind resistance is significant compared with that of the structural members of the tower. Insulators, located between the segments of multi-segment guys. Ancillary libraries containing data describing the physical and drag characteristics of a wide range of antennae types are provided with MsTower. The libraries are plain text files and may be easily added to by users. For a dish antenna the library would typically include its diameter, mass, location of centre of gravity, surface area that may be coated with ice, and its projected area and a drag coefficients for a range of angles of incidence. The use of six drag coefficients (axial and sideways drag, lift, rolling, yawing and pitching moments) for each angle of incidence enables the characteristics of any antennae to be described and for all forces on the antennae to be computed automatically. The use of ancillary libraries simplifies the preparation of the data needed to compute the loads on the tower. To fully describe an antenna the following data is required - its library reference, its location on the tower and its bearing. MsTower will extract all other data from the library, interpolating as necessary, compute the forces (dead load, ice-load and wind loads) acting on the antenna and transfer them into the tower as a set of statically equivalent forces. To assist in checking of input data MsTower displays the tower and all linear and large ancillaries. As well as the visual display, any ancillary may be queried by "picking" with the graphics cursor to obtain its identification, location, library reference and other pertinent data. Wind forces may be computed using either gust or mean wind velocity. In the latter case, the member forces for wind load cases are increased after analysis using gust factors computed in accordance with BS 8100. For masts, patch wind loading cases may be computed and combined in accordance with BS 8100:Part 4. The strength of members may be checked against the rules of the codes listed above, with the results available as a summary report giving the critical load case and condition or a larger detailed report suitable for checking the computations for each member. The results of the member check may be shown as a graphic display with the colour in which a member is displayed depending on its maximum load/capacity ratio. Foundation reactions and ancillary rotations may also be reported.

Acknowledgement Initial development of sections of MsTower was done under contracts with the Independent Broadcasting Authority, Eastern Electricity, British Telecom, and the British Broadcasting Corporation. Particular recognition is due to Mr M J Lambert of the Independent Broadcasting Authority who initiated this work.

Enhancement Record Version 3.1 New menu introduced. TWR file format revised. Terrain blocks introduced. Linear and large ancillary libraries introduced. 32 bit version of programs introduced. Additional standard panels introduced. Gust and Mean keywords added to TWR file. Graphical input of UDPs introduced. Version 3.15 Screen querying of linear ancillary, large ancillary, and ancillary groups introduced with graphical representation of larger ancillaries. Ancillary libraries extended to include Andrew information. HP Laser printers as plotters now supported. Postscript format available for output files. Ancillary deflections and rotations calculated. Foundation reactions calculated. Cross wind and Bare option added. Total mass and additional mass of ancillaries in TWR file. XIP, plan bracing at intersection point of face bracing. Optional Velocity Profile. Version 4 Masts including catenary cables to BS 8100:Part 4 and AS 3995. Additional standard panels. Named node block introduced. Supports block.

Version 4.1 EIA/TIA-222-F-1991. ASCE 10-90 1991 (Manual 52). Bolt checking to DD133/BS5950. Deflections/rotations. Version 4.15 Manual re-set in MSWord. Examples revised. Partial safety factors for materials now applied at member checking stage. Utility programs TDForm, MAKASC and LAZER2R included. Database utilities added for special customers. Bolt data file included. Version 4.20 Shade factor introduced for linear and large ancillaries. Job.OUT file enhanced for results checking. Version 4.21 Tension-only members now available in UDPs; non-linear analysis module required. Version 5.00 Re-developed in Win32 code. Menus and graphics rewritten for the Windows environment; context menus introduced. Ancillary display improved; split view with ancillary labelling. Database recognition and automatic loading from CSV files. Enhanced metafile export of views. Non-linear analysis convergence parameters added. Smear loading for wind on guys. UDP input completely revised. Support for DOS operating system discontinued. Generation of TD and TWR files. Multi-segment guys and guy insulators supported. Asymmetrical ice loading added. Bolt checking to AS 3995, EIA-222, and ASCE 10-90 added.

CTIDATA Function: Generation and or update of a tower data file from a prototype TWR file and Cti.CSV database file. Usage: From the main menu select the Tower > Load Tower > Process Ancillary DB File command. This command will not be available unless a tower geometry has been built and the CSV file exists in the data folder. The prototype TWR file, Ctistd.TWR must be present in the data folder and the geometry of the structure must have been created. A tower loading file is output. When CTIDATA is run a number of dialog boxes are presented for you to choose codes and enter parameters that will be substituted into a copy of the prototype TWR file. A set of wind angle and load combinations is entered for generation of a new LOADS block. All wind load directions are referred to the tower X axis, simplifying the generation of face and corner winds. Any or all face or corner wind directions may be chosen. In addition, for triangular towers, winds parallel to faces may also be chosen. Any large ancillary data in the prototype file is replaced with data derived from the CSV file. If the tower loading file exists before CTIDATA is run, only the large ancillary data will be replaced. The PARAMETERS and LOADS blocks will be unchanged and previously existing ancillary loads will be commented out and remain in the file for possible future reference. Arrangements may be made to customize this program to user requirements.

Example 3

Space Truss

Example 3 is the top section of a high communications tower. It is modelled as a space truss (i.e. all rotational DOF deleted).

EXAMPLE 3

SPACE TRUSS

A common problem with this type of structure is the presence of coplanar nodes. Coplanar nodes have no out-of-plane stiffness because all attached members lie in a plane. Coplanar nodes will give rise to zero stiffness errors during the analysis or a large condition number, with extremely large displacements for the unrestrained DOF. In this example, a number of "redundant" members have been added to the structure to provide out-of-plane support to nodes that would otherwise have been coplanar. A coplanar node may also be removed by deleting the DOF normal to the plane (if the plane is normal to a global axis) or by restraining the node with weak springs. The structure is shown in the accompanying MSTower graphical output. Note in the rendered view that the legs of the tower are oriented with the corners of the angles outwards. The section orientation codes can be seen on some MEMB records of the archive file. These are required only for detailing the analysis is not affected by the orientation of the section. The report shows the analysis results (for a range of nodes and members) for Case 3 , the combination load case. Archive File

* SPACE TRUSS EXAMPLE * TAKEN FROM TOWER 40HBJ101 * * VERS 4 TYPE 4 VERT 2 UNIT 1 m kN t C NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE NODE

261 262 263 264 265 266 267 268 269 270 271 272 701 702 703 704 705 706 707 708

MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB

66 67 133 134 200 201 267 268 578 579 580 581 582 583 584 585 608 609 610 611 612 613 614 615 638 639 640 641 642 643 644 645 668 669 670 671 672

-1.0000 1.0000 1.0000 -1.0000 -1.0000 1.0000 1.0000 -1.0000 -1.0000 1.0000 1.0000 -1.0000 .0000 1.0000 .0000 -1.0000 .0000 1.0000 .0000 -1.0000 261 265 262 266 263 267 264 268 261 701 701 701 265 705 269 705 262 702 702 702 266 267 270 706 263 703 703 703 267 268 271 707 264 704 704 704 268

265 269 266 270 267 271 268 272 701 262 265 266 705 266 705 270 702 263 266 267 706 706 706 271 703 264 267 268 707 707 707 272 704 261 268 265 708

107.0000 107.0000 107.0000 107.0000 108.5000 108.5000 108.5000 108.5000 110.0000 110.0000 110.0000 110.0000 107.0000 107.0000 107.0000 107.0000 110.0000 110.0000 110.0000 110.0000 X X X X X X X X Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y

4 4 4 4 4 4 4 4 7 7 8 8 8 8 7 7 7 7 8 8 8 8 7 7 7 7 8 8 8 8 7 7 7 7 8 8 8

1.0000 1.0000 -1.0000 -1.0000 1.0000 1.0000 -1.0000 -1.0000 1.0000 1.0000 -1.0000 -1.0000 1.0000 .0000 -1.0000 .0000 1.0000 .0000 -1.0000 .0000

111111 111111 111111 111111 000111 000111 000111 000111 000111 000111 000111 000111 111111 111111 111111 111111 000111 000111 000111 000111

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000

000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000

01 01 11 11 10 10 10 10

11 11 10 10

11 11 10 10

11 11 10 10

MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB MEMB PROP PROP PROP

MATL

673 674 675 798 799 800 801 976 977 978 979 980 981

265 272 708 705 705 707 707 701 702 703 704 702 706

708 708 269 708 706 708 706 702 703 704 701 704 708

Y Y Y Y Y Y Y Y Y Y Y Y Y

4 LIBR Asw 1.8100E-03 .0000 7 LIBR Asw 8.6700E-04 .0000 8 LIBR Asw 7.4800E-04 .0000

8 7 7 7 7 7 7 8 8 8 8 8 8

1 1 1 1 1 1 1 1 1 1 1 1 1

000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000

000000 000000 11 000000 11 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000

100X100X10EA Y .0000 5.6200E-08 1.7000E-06 1.7000E-06 75X75X6EA Y .0000 1.1200E-08 4.5500E-07 4.5500E-07 65X65X6EA Y .0000 9.3700E-09 2.9600E-07 2.9600E-07

1 2.000E+08 3.000E-01 7.850E+00 1.080E-05

CASE NDLD NDLD NDLD NDLD NDLD NDLD NDLD NDLD

1 WIND AND DEAD LOADS 261 4.450 -1.388 262 .000 -1.388 263 .000 -1.388 264 4.450 -1.388 269 4.450 -3.595 270 .000 -3.595 271 .000 -3.595 272 4.450 -3.595

.000 .000 .000 .000 .000 .000 .000 .000

.000 .000 .000 .000 .000 .000 .000 .000

.000 .000 .000 .000 .000 .000 .000 .000

.000 .000 .000 .000 .000 .000 .000 .000

CASE NDLD NDLD

2 ANTENNA LOADS 270 7.440 272 7.440

.000 .000

.000 .000

.000 .000

.000 .000

CASE COMB COMB END

3 CASE 1 + CASE 2 1 1.000 2 1.000

-1.079 -1.079

General This chapter describes the MsTower modules for checking the strength of members in latticed towers and masts in accordance with the rules set out in the following codes: BS 8100:Part 3 (DD 133:1986) BS 449 AS 3995-1994 ASCE 10-90 1991 EIA-222-F-1996 The member checking modules use data generated by the tower builder, loading modules, and the results of the static analysis.

Operation Start the code checking module by selecting the appropriate code from the Member Check menu. The report may be limited by selecting classes of members to be checked and setting the report limit on the ratio of design load/capacity. Two forms of report are produced, a summary report and a detailed report. They may be viewed or printed by selecting File > List/Edit and File > Print, respectively. The load/capacity ratios (stress ratios for BS 449) may be displayed graphically by selecting Results > Design Ratios.

Design Loads Axial loads are taken from the results of the analysis (and any subsequent gust-factoring) for legs, braces, and horizontals. Members such as face redundants and hip and plan bracing normally stabilize the load carrying members of the structure and usually attract small or negligible analysis forces. These are designed using the greater of: The force computed from the analysis. 2.5% (1.5% for EIA-222-F) of the axial force in the members they stabilize.

Member Checks to BS 8100: Part 3 (DD 133) Code Type BS 8100 is a limit states code. The capacity of members at the strength limit state is checked. Structural Configuration and Buckling Lengths MSTower uses output from the tower builder (in which the tower data is assembled from a list of panel types and dimensions) to determine the nature of a member and its configuration related to the rules set out in Section 5 of DD 133 to determine buckling lengths. If the face has cross bracing that is not braced against out-of-plane buckling, the forces in both diagonals are determined so that the critical L/r ratios and design capacities may be assessed in accordance with Cl. 5.3.3 of DD 133. Selection of Buckling Curves Buckling curves are selected in accordance with the rules in Section 6.5 of DD 133, using member classification and continuity information generated during tower building. Unless otherwise specified in the tower data file, the checking module assumes that legs, braces, and horizontals are connected with two or more bolts and that redundants and plan and hip bracing are connected with single bolts. Calculation of Ultimate Member Stresses The ultimate stress of the member is calculated from the rules in Section 6 of DD 133. If the section is not one tabulated in DD 133 the reference stress is determined by application of the rules for hot-rolled angles to any elements of the section that have an unsupported free edge. Bolts Bolts are checked for shear on the bolt and bearing on the member using the rules in accordance with Section 9. If any of the dimensions x, y, and z are not specified or set to zero, the checking module assumes that these are equal to or greater than the minimums specified in the code to allow an ultimate bearing strength of 2.0×(D.T.fy) to be attained. Report For each panel in the tower, the report lists the member number, the classification (leg, brace, etc.), the section size and yield strength, the most critical load case, the sub-clause of DD 133 Section 6.5 used in selecting the buckling curve, the slenderness ratio, and whether it is about the x-x, y-y, v-v axes, the axial design force, the capacity and the ratio of design load to capacity. An expanded version of the report, more suitable for detailed checking of the results for particular members is available. This report may be quite large. Restrictions This version of MSTower has the following restrictions: Members are checked for axial force only. No check is made on "man-load" on horizontal or nearly horizontal members.

The value of K used in computing the non-dimensional slenderness of tubular members is taken as 1.0.

Member Checks to BS 449 Code Type BS 449 is a permissible stress design code. The stresses in members at service conditions are checked. Structural Configuration and Buckling Lengths MSTower uses output from the tower builder (in which the tower data is assembled from a list of panel types and dimensions) to determine the nature of a member and its configuration related to the end bolting arrangement to determine effective length factors. Calculation of Permissible Member Stresses The permissible stress in the member is calculated from the formulae in Appendix B of BS 449, with a usersupplied wind overstress factor applied if the member forces due to wind loads increase the member forces due to other causes. Bolts At present, bolted joint checks are not implemented for this code. Report For each panel in the tower, the report lists the member number and classification (leg, brace, etc.), the section size and yield strength, the most critical load case, the effective length factor, the slenderness ratio and whether it is about the x-x, y-y, v-v axes, the axial design force, the actual and permissible stresses (and whether a wind overstress factor is included), and the ratio of the actual to permissible stresses. An expanded version of the report more suitable for detailed checking of the results for particular members is available. This report may be quite large. Restrictions This version of MSTower has the following restrictions: Members are checked for axial force only. No check is made on "man-load" on horizontal or near-horizontal members. Joint capacities are not checked.

Member Checks to AS 3995

Code Type AS 3995 is a limit states code. The capacity of members at the strength limit state is checked. Structural Configuration and Buckling Lengths MSTower uses output from the tower builder (in which the tower data is assembled from a list of panel types and dimensions) to determine the nature of a member and its configuration related to the rules set out in Appendix H of AS 3995 to determine buckling lengths. If the face has cross bracing that is not braced against out-of-plane buckling at the intersection point, the forces in both diagonals are determined so that the critical L/r ratios and design capacities may be assessed in accordance with Figure H2 of AS 3995. Effective Slenderness Ratio Effective slenderness ratios are determined in accordance with Section 3.3.4 of AS 3995, using member classification and continuity information generated during tower building. Unless otherwise specified in the tower data file, the checking module assumes that legs, braces, and horizontals are connected with two or more bolts and that redundants and plan and hip bracing are connected with single bolts. Calculation of Ultimate Member Strength The capacity of a member is calculated from the rules of Section 3.3 for angles in compression and with AS 4100 for other sections in compression and all sections in tension. Bolts Bolted are checked for shear and bearing using the rules of AS 3995 Cl. 3.5.4. No checks are made on the detailed requirements of Cl. 3.5.4.6. Report For each panel in the tower, the report lists the member number, the classification (leg, brace, etc.), the section size and yield strength, the most critical load case, the sub-clause of Section 3.3.4 of AS 3995 used in determining the effective slenderness ratio, the effective slenderness ratio and whether it is about the x-x, y-y or v-v axes, the axial design force, the capacity, and the ratio of design load to capacity. NOTE: In conformity with common international practice, the rectangular axes for ALL sections are nominated as x-x and y-y. For symmetrical sections these axes are also the principal axes. For angles the minor principal axis is nominated as v-v. An expanded version of the report more suitable for detailed checking of the results for particular members is available. This report may be quite large. Restrictions This version of MSTower has the following restrictions: Members are checked for axial force only. No check is made on "man-load" on horizontal or nearly horizontal members.

Member Checks to ASCE 10-90 1991 Code Type ASCE 10-90 is a limit states code. The stresses in members at the strength limit state are checked. Structural Configuration and Buckling Lengths The checking module uses output from the tower builder (in which the tower data is assembled from a list of panel types and dimensions) to determine the nature of a member and its configuration related to the recommendations set out in the Commentary to the ASCE "Guide for Design of Steel Transmission Towers" Second Edition (1988), to determine buckling lengths. If the face has cross bracing that is not braced against out-of-plane buckling at the intersection point, the forces in both diagonals are determined so that the critical L/r ratios and allowable stresses may be assessed in accordance with Example 7 of the design guide. Effective Slenderness Ratio Effective slenderness ratios KL/r are determined in accordance with Section 5.7.4 of ASCE 10-90, using member classification and continuity information generated during tower building. Unless otherwise specified in the tower data file, the checking module assumes that legs, braces, and horizontals are connected with two or more bolts and that redundants and plan and hip bracing are connected with single bolts. Calculation of Allowable Stresses The allowable stresses are calculated from the rules of Section 5.6 for compression members and Section 5.10 for tension members. Flexural stresses are not checked. Bolts Bolts are checked for shear and bearing in using the rules of Cl. 6.3.2 and Cl. 6.4. No checks are made on edge distance or spacing requirements. Report For each panel in the tower, the report lists the member number, the classification (leg, brace, etc.), the section size and yield strength, the most critical load case, the sub-clause of Section 5.7.4 of ASCE 10-90 used in determining the effective slenderness ratio, the effective slenderness ratio, and whether it is about the x-x, y-y or v-v axes, the axial design force, the capacity and the ratio of design load to capacity. An expanded version of the report more suitable for detailed checking of the results for particular members is available. This report may be quite large. Restrictions This version of member checking to ASCE 10-90 has the following restrictions: Members are checked for axial force only. No check on "man-load" on horizontal or nearly horizontal members is made.

Member Checks to EIA-222-F 1998 Code Type EIA-222-F is an allowable stress code. The stresses in members under service loads are checked. Structural Configuration and Buckling Lengths The checking module uses output from the tower builder (in which the tower data is assembled from a list of panel types and dimensions) to determine the nature of a member and its configuration related to the recommendations set out in the Commentary to the ASCE Manuals and Reports on Engineering Practice No. 52 "Guide for Design of Steel Transmission Towers" Second Edition (1988), to determine buckling lengths. If the face has cross bracing that is not braced against out-of plane buckling at the intersection point, the forces in both diagonals are determined so that the critical L/r ratios and allowable stresses may be assessed in accordance with Example 7 of the design guide. Effective Slenderness Ratio Effective slenderness ratios KL/r are determined in accordance with the rules of ASCE Manual 52 using member classification and continuity information generated during tower building. Unless otherwise specified in the tower data file, the checking module assumes that legs, braces, and horizontals are connected with two or more bolts and that redundants and plan and hip bracing are connected with single bolts. Calculation of Allowable Stresses The allowable stresses, including any appropriate wind overstress factors, are calculated from the rules of Section 3. Flexural stresses are not checked. Bolts Bolts are checked for shear and bearing using the rules in Chapter J of the AISC "Specification for Structural Steel in Buildings 1989". No checks are made on edge distance or spacing requirements. Report For each panel in the tower, the report lists the member number, the classification (leg, brace, etc.), the section size and yield strength, the most critical load case, the sub-clause of Manual 52 used in determining the effective slenderness ratio, the effective slenderness ratio and whether it is about the x-x, y-y or v-v axes, the axial design force, the capacity, and the ratio of design load to capacity. An expanded version of the report more suitable for detailed checking of the results for particular members is available. This report may be quite large. Restrictions This version of member checking to EIA-222-F has the following restrictions: Members are checked for axial force only.

No check is made on "man-load" on horizontal or nearly horizontal member.

Obtaining Design Results After checking members the results may be displayed or reported in a number of ways: Use the Results > Design Ratios command to display design results with members color-coded to show the percentage of member capacity actually utilized in the critical load case. With this display, all members that have failed a design check are shown in a shade of red. Use the Query > Design Member command to show a summary of design results in the output window for any selected member. The design reports may be previewed with the File > Print Preview command and may be printed with the File > Print File command. Note that there are extensive facilities for formatting the design report using the File > Page Setup command. The report files are automatically deleted when the job is closed. The member check reports are created in the data folder and are named: Job.RPT summary report Job.RP2 detailed report, where "Job" is the job name. You may save a steel design report file by dragging it to another folder using Windows Explorer.

Steel Detailing Information may be exported in SDNF format for transfer to third-party steel detailing programs (e.g. Xsteel). Refer to Exporting a Steel Detailing Neutral File.

Editing the Steel Section Library The File > Configure > Edit Section Library command allows you to add section properties and material properties to library files or to generate new library files. Library files have the file name extension "LIB" (e.g. As.LIB, Uk.LIB) and cannot be listed, printed, or edited. For each library file, a corresponding source file contains the data from which the library file is generated. Library source files are ordinary text files having a file name extension of "ASC" (e.g. As.ASC, Uk.ASC).

On selecting the above command, a dialog box is displayed for you to choose one of the library source files. These are displayed with a prefix, "Prog:", "Data:", or "Libr:", indicating the folder in which it is located. The MsEdit program then starts for you to edit the selected file. When you close MsEdit a message box asks if you want to make the library file. Answer Yes for MsTower to create the new library file. Data required for the section library is: ltype lvers title nu u1 u2 u3 u4 S dt name d1 ... dn f y1 y2 ... ...

where: ltype lvers title nu u1 u2

u3 u4 S dt name d1..dn

f y1 y2

Library type, always 6. Version, always 1. Library description. Number of conversion factors, always 4. Number of mm in units used to give the dimensions of the section. Number of mm in units used to give the derived properties of the section. In UK libraries, dimensions are normally in mm while derived properties are in cm, so u1 = 1.0 and u2 = 10.0. Number of kg/m in units used to give the mass/unit length of the section. Number of N/mm2 (MPa) in units used to give the yield strengths of the section. Character "S", in the first column of the line. Design type, tabulated below. Section name, not more than 15 character, with no embedded spaces. Section data, consisting of section properties and dimensions. Each design type requires a different set of data, as tabulated below. Always 0. Yield strength for normal grade steel. Yield strength for high strength steel.

Note that the library type, title, and conversion factors must be on the first, second, and third lines, respectively of the file. They will normally be present and will not require editing. You must ensure that any data you enter is in units consistent with those of the rest of the library. The format of the library source file is specified for each design type in the tables below. There are template records in the library source file to help you add new data correctly. The value of any section property input as zero is computed automatically provided sufficient dimensions for the calculation have been input. In these calculations, fillets and chamfers are neglected. For compound sections, dimensions are for a single component. Design Type

1

TFB

2

UB, WB

Taper flange beam Universal beam or welded beam 3 UC, WC Universal column or welded column 4 RHS Rectangular hollow section 5 SHS Square hollow section 6 CHS Circular hollow section 7 PFC Parallel flange channel 8 Tee Tee section 9 EA Equal angle 10 UA Unequal angle 11 DAL Double angles, long legs together 12 DAS Double angles, short legs together 16 STA Starred angles 22 QAN Quad angles 13 UBP Universal bearing pile 17 TFC Taper flange channel 18 Rod Round 19 Bar Rectangular bar 20 CTT Double channels, toes together 21 CBB Double channels, back-to-back 24 CA DuraGal cold-formed angle 25 CC DuraGal cold-formed channel 30 *** Section with analysis properties only The section mnemonic is embedded in the section name and, for a library section, is the only part of the name that may be alphabetic. Every section in a section category must have the same section mnemonic. During the design process you specify the kind of sections that may be selected by entering one or more section mnemonics (see above). The section mnemonics that are entered are used to extract design candidate sections from the library. The available types of compound section are shown in the diagram below.

COMPOUND SECTIONS Key to Section Library Parameters

Part 1 of 3

DT Type 1

2

3

4

5

6

7

8

9

10

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

TFB UB UC RHS SHS CHS PFC T EA UA DAL DAS UBP CB CC STA TFC ROD

A A A A A A A A A A A A A A A A A A

Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax Ax

Ay Ay Ay Ay Ay J Ay Ay J Ay Ay Ay Ay Ay Ay Ay Ay J

J J J J J Ix J J Ix J J J J J J J J Ix

Ix Ix Ix Ix Ix rx Ix Ix rx Ix Ix Ix Ix Ix Ix Ix Ix M

Iy Iy Iy Iy Iy Zx Iy Iy Zx Iy Iy Iy Iy Iy Iy Iy Iy D

Zx Zx Zx Zx Zx tw Zx Zxs t Zx Zx Zx Zx Zx Zx Zx Zx f

rx rx rx rx rx M rx rx M rx rx rx rx rx rx rx rx y1

ry ry ry ry ry D ry ry D ry ry ry ry ry ry ry ry y2

Zy Zy Zy Zy Zy Sx Zyt Zy Sx Zy Zy Zy Zy Zy Zy Zy Zyt

19 20 21 22 30

BAR CTT CBB QAN ***

A A A A A

Ax Ax Ax Ax Ax

Ay Ay Ay Ay Ay

J J J J J

Ix Ix Ix Ix Ix

Iy Iy Iy Iy Iy

M Zx Zx Zx

D rx rx rx

B ry ry ry

f Zy Zy Zy

2

3

4

5

6

7

8

9

10

DT Type 1

Key to Section Library Parameters DT Type 11 12

Part 2 of 3

13 14 15 16

17 18 19 20

TFB UB UC RHS

M M M M

D D D D

B B B B

tf tf tf tw

tw tw tw Sx

RR RR RR Sy

DF DF DF f

Sx Sx Sx y1

5 SHS

M

D

B

tw

Sx

Sy

f

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6 CHS

f

y1

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PFC T EA UA DAL DAS UBP CB CC STA TFC ROD

M M cy M Sx Sx M M M Sx M

D D ex D Sy Sy D D D Sy D

B B Iu B M M B B B M B

tf tf Zu1 t D D tf tf tf D tf

tw tw ru Sx B B tw tw tw B tw

RR RR Iv Sy t t RR RR RR t RR

DF DF Zv1 cx g g DF DF DF g DF

19 BAR

y1

y2

20 21 22 30

Sx Sx Sx

Sy Sy Sy

M M M

D D D

B B B

tf tf t

tw tw g

1 2 3 4

7 8 9 10 11 12 13 14 15 16 17 18

CTT CBB QAN ***

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Iw Iw Iw

Sx Sx rv cy sp sp Sx Sx Sx sp Sx

Sy Sy tan ex rv rv Sy Sy Sy rv Sy

Iw Iw f ey f f Iw Iw Iw f Iw

g g sp

sp sp rv

ry ry f

DT Type 11 12

13 14 15 16

Key to Section Library Parameters DT Type 21 22 23

17 18 19 20 Part 3 of 3

24 25 26 27

1 TFB

f

y1

y2

2 UB

f

y1

y2

3 UC

f

y1

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7 PFC

cy

Zyw ey

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9 EA

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10 UA 11 DAL

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Iv

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12 DAS

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13 UBP

f

y1

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14 CB

f

y1

y2

15 CC

f

y1

y2

16 STA

y1

y2

17 TFC

cy

Zyw ey

f

y1

20 CTT

f

y1

y2

21 CBB

f

y1

y2

22 QAN

y1

y2

28 29 30

4 RHS 5 SHS 6 CHS y2

tan f

y1

y2

y2

18 ROD 19 BAR

30 ***

DT Type 21 22 23 Legend A Ax Ay J Ix Iy rx ry Zx Zy M D B tf tw RR

= = = = = = = = = = = = = = =

24 25 26 27

I Section Gross area Shear area Shear area Torsion constant Second moment of area Second moment of area Radius of gyration Radius of gyration Elastic modulus Elastic modulus Mass per unit length Depth Breadth Flange thickness Web thickness

28 29 30

DF Sx Sy Iw f y1 y2

= = = = = = = =

Legend cy

= ey = Zyt = Zyw = Legend cx

= Zxs = Zxf = Legend D B t cx cy ex ey Iu Iv ru rv Zu1 Zv1 Zv2 tan

= = = = = = = = = = = = = = =

Legend g sp

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Root radius Depth between fillets Plastic modulus Plastic modulus Warping constant Residual stress code Yield normal strength steel Yield high strength steel Channel Distance to center of area Distance to shear center Elastic modulus toe Elastic modulus web Tee Distance to center of area Elastic modulus stem Elastic modulus flange Angle Length of long leg Length of short leg Thickness Distance to center of area Distance to center of area Distance to shear center Distance to shear center Second moment of area major Second moment of area minor Radius of gyration Radius of gyration Elastic modulus toe Elastic modulus heel Elastic modulus toe Tangent of angle to principal axes Compound Sections Gap between component sections Stitch bolt or packer spacing

Editing Ancillary & Guy Libraries The File > Configure > Ancillary/Guy Library command allows you to add additional ancillaries or guys to these libraries. There are template records in each library to help you add new data correctly. On selecting the above command, a dialog box is displayed for you to choose one of the library source files. These are displayed with a prefix, "Prog:", "Data:", or "Libr:", indicating the folder in which it is located. The MsEdit program then starts for you to edit the selected file. The data required in each of these library types is set out in Guy Library and Ancillary Libraries. The examples in this chapter are presented to illustrate specific features of MSTower. Examples have been chosen to include several common problem areas in modelling, especially node restraint conditions and member releases. For all examples the archive file is presented as a complete record of the input data. It is possible to enter data by creating the archive file but it is not usually the most convenient input method. Many common structures can be described easily with Standard Structures Input (see Error! Reference source not found. on page Error! Bookmark not defined.). Report presentations have been varied to demonstrate different features of the report generator. A wide variation of formats is possible by modifying the default values in the Page Setup dialog box (see Error! Reference source not found. on page Error! Bookmark not defined.).

General MSTower offers a number of static and dynamic analysis options, each of which employs exhaustive consistency checking and highly efficient equation solution procedures. The analysis engines used in MsTower are derived from those used in Microstran, a widely used and extremely versatile program for analysing and designing structural frameworks in steel and reinforced concrete. Linear Elastic Analysis is a first-order elastic static analysis in which non-linear effects are ignored and the stiffness equations are solved for only the primary load cases. Solutions for combination load cases are obtained by superposition of the solutions for the primary load cases. Non-Linear Analysis is a second-order elastic analysis, which enables you to take into account the nonlinear actions arising from the displacement of loads (the P- effect), the change in flexural stiffness of members subjected to axial forces (the P- effect), and the shortening of members subjected to bending (the flexural shortening effect). Non-linear analysis is an iterative procedure in which the behaviour at each step is controlled by a number of parameters. Each selected case, whether a primary or combination load case, must be solved separately, as superposition of results cannot be used. Members defined as tension-only will be checked at each iteration and included or excluded accordingly. Elastic Critical Load Analysis calculates the frame buckling load factor, c, for selected load cases and computes the corresponding member effective lengths for each load case. Dynamic Analysis computes the natural vibration frequencies of the structure and the associated mode shapes. The dynamic loads on the structure due to earthquake or other support acceleration may then be assessed using the response spectrum method. The Profile Optimizer is used in all analyses to minimize analysis time and storage requirements. Nodes and members can therefore be numbered for maximum convenience in data generation and interpretation of results. More: Method Consistency Check Accuracy

Method MSTower uses the well-documented direct stiffness method of analysis in which the global stiffness matrix, [K], is assembled from the stiffness contributions of individual members. For large structures, [K] can be quite large and is stored on disk in blocks sized to maximize the use of available memory and to minimize solution time. Load vectors, P, are formed from the applied loads and node displacements, u, are determined by solving the equation: P = [K] u The forces in each member are then determined by multiplying the member stiffness matrix by the appropriate terms of the displacement vector, resolved into member axes.

Consistency Check MSTower performs an automatic check of all input data prior to analysis. The consistency check will detect a range of modelling problems related to geometry and loading. Data errors and warnings are shown in the output window and are also written to the error report, which can be listed and printed using options on the File menu.

Accuracy All analyses use double-precision arithmetic to minimize the loss of precision inherent in the many arithmetic operations required for solving large, complex structural models. After the decomposition of the [K] matrix MSTower reports the maximum condition number, a measure of the loss of precision that has occurred during the solution. For "well-conditioned" structural models (those in which little numerical precision is lost) the condition number will be less than 104. If the condition number exceeds this value you should treat the results with caution and look for evidence of "ill-conditioning". For example, the large displacement of a node or group of nodes may indicate that the structure is acting, to some extent, as a mechanism, and the results could be meaningless. An important independent check on the accuracy of the solution is provided by the node equilibrium check. At unrestrained nodes the sum of all the member end actions is compared to the sum of external forces acting on the node. Any difference is a force residual, the out-of-balance force. The maximum residual is reported to the screen after the analysis. The maximum residual should be considered in conjunction with the magnitudes of the applied loads in assessing the adequacy of the solution. Note: A satisfactory equilibrium check, by itself, is not sufficient to ensure an accurate solution condition number must also be satisfactory.

the

MsTower will choose the appropriate method of analysis when Tower > Analyse is selected. Linear analysis will be used unless the tower contains tension-only members or guys (cables).

Linear Elastic Analysis Linear elastic analysis cannot be performed if there are any tension-only or cable members in the model. An error message will be displayed if you attempt linear analysis of a model containing these member types. All load cases are analysed when you choose linear analysis. Results for combination load cases are determined by superposition of the results of the component primary load cases. Note: If you perform a non-linear analysis and then a linear analysis, the settings in the Select Analysis Type dialog box will be lost (see Selecting Load Cases for Non-Linear Analysis). Performing a linear

analysis sets the analysis type flag to L (linear).

Non-Linear Analysis Non-Linear Analysis (also called second-order analysis) performs an elastic analysis in which second-order effects may be considered. The different second-order effects are described below. Non-linear analysis uses a multi-step procedure that commences with a linear elastic analysis. The load residuals, computed for the structure in its displaced position and with the stiffness of members modified, are applied as a new load vector to compute corrections to the initial solution. Further corrections are computed until convergence occurs. There is no single method of iterative non-linear analysis for which convergence is guaranteed. It may therefore be necessary to adjust the analysis control parameters in order to obtain a satisfactory solution. The solution may not converge if the structure is subject to gross deformation or if it is highly non-linear. This may be the case as the elastic critical load is approached. Note: You should not attempt to use non-linear analysis to determine elastic critical loads. Results of nonlinear analysis should be treated with caution whenever the loading is close to the elastic critical load. More: Second-Order Effects Running a Non-Linear Analysis Troubleshooting Non-Linear Analysis

Second-Order Effects The most important second-order effects taken into account in non-linear analysis are the P-Delta effect (P) and the P-delta effect (P- ). These are discussed in detail below.

P- AND P- EFFECTS You may independently include or exclude these two major effects. Different combinations of the P- and P- settings affect the operation of non-linear analysis as set out in the table below.

Node Coordinate Update NO

Axial Force Effects NO

YES

NO

NO

YES

YES

YES

Analysis Type Linear elastic analysis with tension-only or compression-only members taken into account. This can be achieved for any load case by selecting linear analysis Analysis includes the effects of displacement due to sidesway but not changes in member flexural stiffness due to axial force. These settings will usually yield satisfactory results for pin-jointed structures. Full account is taken of the effects of axial force on member flexural stiffness while the effects of node displacement are approximated by a sidesway correction in the stability function formulation. These settings normally give minimum solution time with second-order effects taken into account. This is the default analysis type, which provides the most rigorous solution for all structure types.

More: Node Coordinate Update Axial Force Effects

P-Delta Effect

P-delta Effect

Changes in Fixed-End Actions Non-Linear Members

Node Coordinate Update

P-Delta Effect

The P-Delta effect (P- ) occurs when deflections result in displacement of loads, causing additional bending moments that are not computed in linear analysis. P- is taken into account either by adding displacement components to node coordinates during analysis or by adding sidesway terms to the stability functions used to modify the flexural terms in the member stiffness matrices. Either small displacement theory or finite displacement theory may be used with node coordinate update. As shown in the diagram below, finite displacement theory takes into account the rotation of the chord of the displaced member in computing the end rotations and the extension of the member. Only where large displacements occur would the use of finite displacement theory produce results different from those obtained with small displacement theory.

SMALL AND FINITE DISPLACEMENT THEORIES

Axial Force Effects

P-delta Effect

The bending stiffness of a member is reduced by axial compression and increased by axial tension. This is called the P-delta effect (P- ) and is taken into account by adding beam-column stability functions to the flexural terms of the member stiffness matrices. Member stiffness matrices therefore vary with the axial load and are recomputed at every analysis iteration. The stability functions are derived from the "exact" solution of the differential equation describing the behaviour of a beam-column. The additional moments caused by P- are approximated in some design codes by the use of moment magnification factors applied to the results of a linear elastic analysis.

Changes in Fixed-End Actions Member fixed-end actions may change between successive analysis iterations owing to displacement of the member and variations in its flexural stiffness caused by axial force. MSTower automatically recalculates the fixed-end actions at each analysis iteration and updates the load vector accordingly.

Non-Linear Members Analysis of structures containing tension-only, or cable members requires non-linear analysis. At the conclusion of each analysis step, all members nominated as tension-only or compression-only are checked and either removed from or restored to the model for the next analysis step, according to their deformation. If the removal of non-linear members causes the structure to become unstable, no solution is possible.

Running a Non-Linear Analysis Selecting Load Cases for Non-Linear Analysis Non-Linear Analysis Parameters

Selecting Load Cases for Non-Linear Analysis Non-linear analysis lets you specify the load cases to be analysed and the analysis type (linear or non-linear) to be used for each. For non-linear analysis a load vector is formed for each load case to be solved, whether a primary load case or a combination load case. There is no need to analyse any load cases for which results are not required. On selecting the Analyse > Non-Linear command, the following dialog box is displayed so you may specify the load cases to be analysed and the analysis type. In the Type column, load cases are identified as Primary or Combination. The second character is a code that specifies whether the load case is to be processed with Linear analysis or Non-linear analysis, or is to be ignored (Skipped).

SELECTING LOAD CASES FOR NON-LINEAR ANALYSIS The ability to use different analysis types is used for obtaining results for both linear and non-linear analysis in a single pass. This may be necessary where the model includes members to be designed to different codes with different analysis requirements. In general, only "realistic" load cases should be selected for non-linear analysis there is no point in analysing a wind load case because this load will never exist in isolation. This is particularly important for structures containing cable elements where realistic loads including self weight are required to determine the equilibrium position of each cable, and a solution may not be possible for load cases containing only some load components. Note: The settings in this dialog box will be lost if you subsequently perform a linear analysis. In this case, the analysis type flag (S/L/N) will be unconditionally set to Linear. You must reinstate the analysis type flag if you revert to non-linear analysis.

Non-Linear Analysis Parameters The next dialog box determines the type of non-linear analysis that will be performed for load cases selected for non-linear analysis.

NON-LINEAR ANALYSIS PARAMETERS The dialog box contains the following items: Node coordinate update (P- ) This flag is set if node coordinates are to be updated at each analysis step. It is automatically set for structures containing cable elements. The default setting is on. Small/finite displacement theory If the node coordinate update flag has been set, either small or finite displacement theory must be selected. Small displacement theory is the default setting. Axial force effects (P- ) If this flag is set member stiffnesses are modified at each analysis step. The default setting is on. Residual / displacement Specifies the criterion to be used for convergence of the solution. Residual uses a function of the maximum out-of-balance force after analysis. When Displacement is selected, convergence is checked by comparing the convergence tolerance against a generalized measure of the change in displacement between successive iterations. For a satisfactory solution there must be acceptably small changes in the displacement and the residual must be of a low value. The default setting is Residual. Displacement control Increasing the setting of this control will assist convergence in situations where displacements appear to diverge with successive analysis iterations, or for structures that are initially unstable but become stable as they displace under load. You normally leave this control at minimum and only increase the setting if difficulties are encountered in solution. Convergence tolerance This value determines when the analysis has converged, determined by checking the change in the convergence criterion between successive analysis cycles. Too small a value will prolong the solution time and may even inhibit convergence. The default value is 0.0005. No. load steps You may apply loads in a stepwise fashion which may assist in obtaining a solution for flexible structures by keeping displacements small at each load increment. This parameter is usually left at its default value of 1. Iterations per load step The maximum number of analysis iterations for each load step. This parameter is used to stop the

analysis if convergence is taking an excessive time. The default value is 50, but larger values are often applicable for very flexible structures or models containing large numbers of cable elements. Relaxation factor The relaxation factor is applied to incremental displacement corrections during analysis. The optimum value for the relaxation factor depends on the type of the structure. As a general rule, structures which "soften" under load (i.e., displacements increase disproportionately with load) have an optimum relaxation factor between 1.0 and 1.2 while structures which "harden" under load have an optimum relaxation factor as low as 0.85. Caution is recommended in changing the relaxation factor from the default value of 1.0; if the relaxation factor is too far from optimum the analysis may require an excessive number of iterations for convergence or it may not converge at all. Oscillation control This control facilitates convergence when the solution oscillates owing to the removal and restoration of tension-only or compression-only members. The default setting is off. As the analysis proceeds, the analysis window displays key information for each selected load case. At each analysis iteration the maximum values of residual and displacement are displayed in correct user units. Note that at this stage the values shown are from the most critical degree of freedom, i.e., residuals may be either forces or moments, and displacements may be either translations or rotations.

Troubleshooting Non-Linear Analysis It is possible to perform a successful linear analysis for structures that are incapable of resisting the imposed loads. Non-linear analysis is a more complete simulation of the behaviour of a structure under load and the procedure will often fail to provide a solution where a linear analysis succeeds. This may occur, for example, if some compression members are slender and buckle. Where non-linear analysis fails to converge, the following tips may be helpful: Make sure that a linear analysis can be performed. If not, troubleshoot the linear analysis before continuing with the non-linear analysis. Is a full non-linear analysis necessary? If the only significant non-linear effect is the presence of tension-only or compression-only members, set the analysis type to L for these load cases. In other cases, a successful analysis may result if either node coordinate update or axial force effects can be excluded. Examine the analysis log file. It contains information about members that have become ineffective because of slenderness or member type. Note that members in this file are referred to by index rather than label. The member index number is the serial number of the member in the archive file (not the member number). Perform an elastic critical load analysis to check the frame buckling load. If it is greater than the imposed load non-linear analysis is not possible. Is the structure too flexible? Remove excessive member end releases (pins). Sometimes, in diagnosing convergence problems, it is helpful to remove ALL releases and reinstate them in stages. Adjust non-linear analysis parameters.

Elastic Critical Load Analysis Elastic Critical Load (ECL) Analysis (also referred to as stability, or buckling analysis) performs a rational buckling analysis of the model to compute the elastic critical load factors ( c) and the associated buckling modes. Member effective lengths can also be determined from the elastic critical load. The buckling behaviour depends on the distribution of loading on the frame and buckling parameters are computed separately for each load case to be considered. The buckling load factor for any load case is the factor by which the axial forces in all the members must be multiplied to cause the structure to become unstable (lateral torsional buckling of individual members is not taken into account). The elastic critical load of the structure is a function of the elastic properties of the structure and the pattern of loading. The effective length of a member is defined as the length of an ideal pin-ended strut whose Euler load is the axial load in the member when the structure is at its critical load. The effective length may be expressed as a factor multiplying the actual member length (k). The effective length factor is calculated separately for each of the member principal axes for each load case. A load factor of less than 1.0 for any load case indicates that the structure is unstable under the applied loading. A linear elastic analysis is often used for the initial analysis, but non-linear analysis must be used when the structure contains non-linear members. For most structures the load factor will not be influenced greatly by the type of initial analysis and a linear analysis is recommended in order to reduce the overall solution time. Restraints affecting the flexural buckling behaviour of the structure must be included in the structural model. For example, if out-of-plane buckling behaviour is to be considered for a plane frame, the frame would have to be modelled as a space frame with nodes located at the positions of lateral restraints (restraint can be introduced only at nodes). Elastic critical load analysis is not recommended for structures containing cable elements because of the highly non-linear nature of structures of this type. More: Selecting Load Cases for ECL Analysis Analysis Control Parameters Why Does ECL Analysis Give Such High k Factors?

Selecting Load Cases for ECL Analysis Select Analyse > Elastic Critical Load from the main menu. The dialog box below is displayed for you to select the required load cases. Usually, only combination load cases required for design are selected.

SELECTING LOAD CASES FOR ECL ANALYSIS

Analysis Control Parameters After selecting load cases, the dialog box shown below appears. The settings in this dialog box determine the type of elastic critical load analysis that will be performed.

ECL ANALYSIS PARAMETERS The dialog box contains the following items: Initial analysis The initial analysis determines the distribution of axial forces to be used for the elastic critical load analysis. It is normally Linear but should be Non-linear if the structure contains tension-only, compression-only, or cable members. Tolerance The tolerance is the relative accuracy to which the load factor is required. Too small a value will prolong the solution time. The default value is 0.01. Max. load factor The search for the elastic critical load will terminate if the load factor exceeds this limiting value. The default value is 1000. No. modes The number of buckling modes to be computed for each selected load case. Normally, only the first mode is required, though higher modes may be of interest if lower modes are inhibited or represent localized buckling behaviour. When the analysis is finished a summary of results appears in the analysis window. The summary shows for each selected load case the critical load factor and the most critical member with associated k values.

Why Does ECL Analysis Give Such High k Factors? The effective length of a given member in a frame is the length of an equivalent pin-ended member whose Euler load equals the buckling load of the frame member. The effective length factors, kx and ky, are factors by which we multiply the actual length of the member in order to obtain the effective lengths for buckling about the section XX and YY axes, respectively. When designing the frame member by traditional methods, we take account of the stiffness of connected members to obtain the effective length and then we consider it as if it were an isolated member of an appropriate length. We could then determine the axial load required to cause column buckling in this equivalent member. ECL analysis allows us to determine the frame buckling load factor for a given load case. Frame buckling occurs when the axial forces for the given load case are factored to the point where the frame collapses. Display the buckling mode shape of the frame and you can see how the frame buckles. Frame buckling for a given load case is usually a complex interaction of several members there is not necessarily any one member that causes the buckling of the frame. In this situation, if we apply our definition of effective length, we find that the effective length of a given member for a given load case is the length of an equivalent pinended member whose Euler load equals the load in that member when frame buckling occurs. Thus, any member carrying a small axial load at frame buckling will have a large effective length. Also, the effective length of a member will vary from one load case to another. It is only where a member could be said to be critical (i.e. participating to a very large degree in the buckling mode), that the effective length factor could be compared with the value used in traditional methods. In general, traditional effective length factors relate to the buckling load of the member being considered whereas the effective length factor computed by ECL analysis relates to frame buckling.

Dynamic Analysis Dynamic Analysis computes the frequencies and mode shapes of the natural vibration modes of the structural model. Only the mass and stiffness of the model are considered in computing natural frequencies and mode shapes. Static load cases are ignored. The frame mass is computed automatically and additional mass that is to be taken into account may be modelled as node masses. Member masses are computed automatically as the product of the cross-sectional area and the mass density. Additional node masses may be input as required. The unit used for mass must be consistent with the force and length units. Select the Analyse > Dynamic command to start dynamic analysis. More: Analysis Control Parameters Dynamic Modes Dynamic Analysis Example

Analysis Control Parameters After selecting load cases, the dialog box shown below appears. The settings in this dialog box determine the type of dynamic analysis that will be performed.

DYNAMIC ANALYSIS PARAMETERS The dialog box contains the following items: No. modes The number of natural frequencies and mode shapes that can be computed is limited by the number of dynamic degrees of freedom, and, for large structures, by the amount of available memory. Solving for a large number of modes is usually not warranted. Tolerance This is the tolerance to be used in determining the convergence of eigenvalues. If the value is too small, convergence may not be possible or an excessive number of iterations may be required. If the value is too large, the eigenvalues found may not be the lowest. The default value is 0.00001. Verify eigenvalues Check this box if you wish to verify that no eigenvalues have been skipped in the computation (see above). Lumped mass / Consistent mass The mass matrix may be computed using either a consistent mass or lumped mass formulation. The consistent mass matrix has a firmer theoretical basis but gives rise to a global mass matrix that is similar in shape and size to the global stiffness matrix, requiring greater storage and computational effort than the lumped mass matrix, which leads to a diagonal global mass matrix Initial state load case Non-linear behaviour is not taken into account in dynamic analysis but it is possible to specify a load case that defines the initial state. For example, a leeward cable in a guyed mast subjected to wind load may be slack. If the corresponding load case is specified as the initial state load case, the slack cable will be eliminated from the analysis. The default value is zero. Response spectrum analysis You must check this box if you wish to proceed to a response spectrum analysis after the dynamic analysis.

Dynamic Modes After completing a dynamic analysis it is important to check the mode shapes to ensure that you have the required dynamic modes. MsTower computes all dynamic modes, including torsional modes. The easiest way to examine the results is to display an animated view of the computed mode shapes. Note: You can add low-mass "semaphore" members to visualise torsional modes.

Dynamic Analysis Example The diagram below shows the mode shape computed for the first mode in dynamic analysis of the TWEX5 example.

NATURAL MODE SHAPE

Response Spectrum Analysis The Response Spectrum Analysis is used to determine peak displacements and member forces due to support accelerations using the response spectrum method. The spreadsheets AS1170_4.xls (see http://www.microstran.com/as1170_4.htm) and Nzs4203.xls (see http://www.microstran.com/nzs4203.htm) set out detailed procedures for performing response spectrum analysis complying with the design codes AS 1170.4 and NZS 4203, respectively. More: Running a Response Spectrum Analysis Response Spectrum Curves

Running a Response Spectrum Analysis

The procedure for performing a response spectrum analysis is: 1. Set up static analysis load cases and perform the static analysis. The earthquake load cases are empty results from the response spectrum analysis will be added automatically. 2. Select dynamic analysis and check Response spectrum analysis.

3. You are next prompted to identify the load cases that are to be used for the results of the response spectrum analysis. There will be one such load case for each earthquake direction being considered.

4. For each earthquake load case you must enter parameters to determine the response spectrum direction and the number of modes to be considered. The direction factors determine the direction of the support acceleration in terms of components in the global axis directions. These components will be reduced to a unit vector before being used. The number of modes must be sufficient to satisfy the earthquake code requirement that 90% (typically) of the seismic mass is accounted for. It must not be greater than the number of modes computed during dynamic analysis (Step 2, above).

5. For each earthquake load case damping ratios are specified. The "Complete Quadratic Combination" method (CQC) for combining modal responses is used to determine the peak response. This is equivalent to the "Square Root of the Sum of Squares" (SRSS) method if all modal damping ratios are zero.

6. For each earthquake load case a response spectrum curve and scaling factor must be specified. The response spectrum curve is chosen from a list of names of digitized response spectrum curves contained in file Response.txt (described below). You may edit the response spectrum curves or add new ones using the Configure > Edit Response Spectra command.

7. After Steps 3-6 have been completed for each earthquake case, the dynamic analysis proceeds. On completion, select the Analyse > Response Spectrum command to scale the computed actions and combine them with the static analysis results (note that this item is greyed out on the menu until all the necessary preconditions for response spectrum analysis have been completed). The total reactions (base shears) are displayed for each earthquake case and you now enter scale factors for each case. The spreadsheets referred to above will assist you in computing scale factors to comply with code requirements.

MsTower now adds the results from the response spectrum analysis to the static analysis results. Earthquake load cases may now be treated as any other load case for the display and reporting of results and for design. Note: The displaced shape represents the peak values of the displacement during the earthquake event. There are no negative values. Interpretation of the results should take this into account. Response Spectrum Scale Factor The scale factor used in Step 6, above is used to multiply the spectral acceleration values to give the actual support acceleration to be used in the analysis. Many codes give spectral accelerations in a normalized form that have to be multiplied by site acceleration factors. For convenience, file Response.txt uses normalized spectral values. The results of the static analysis are updated with the results of the response spectrum analysis. As this process takes place, the sum of the reactions for each dynamic load case will be displayed and you may enter factors that will be used to scale the results to ensure compliance with codes that require minimum base shears (Step 7, above). The factor should be based on the base shear in the direction of the support acceleration. Note that the values given for the reactions are the sum of absolute values, as the methods used to combine individual modal responses result in loss of sign. The results for each dynamic load case are inserted in the results files for the previously defined empty load cases. Any combination case that refers to the dynamic case is updated by adding the specified dynamic case, factored as specified. By updating combination cases instead of computing them completely from the results of primary cases, any non-linearity in the previously computed results is preserved. However, the static analysis must be repeated if the dynamic analysis is to be amended. Note: After running response spectrum analysis you should look at the dynamic analysis log file, which contains important data including mass participation factors.

Response Spectrum Curves

The digitized data for the response spectrum curves must be entered into the file Response.TXT. The Response.TXT file resides in the library folder. This is a text file that may be edited by the user to add additional response spectrum data. The format of each set of data in the file is as follows: Name T(1) Sa(1) T(2) Sa(2) T(3) Sa(3) ..... T(n) Sa(n) END

where: Name

String of alphanumeric characters used to identify each curve. Period in seconds for the nth point on the curve. Spectral acceleration for the nth point on the curve. The spectral accelerations may be in normalized form or as absolute accelerations with a scale factor, described previously, being used to effect any required conversion. Keyword indicating the end of data for this curve.

T(n) Sa(n)

END

Errors There are some types of error that only become evident during analysis and it is not possible for the consistency check to warn of this type of error before the analysis commences. For example, if a structure is unstable because some part of it actually forms a mechanism, analysis will be terminated and an error message will be displayed on the screen. The error message is of the form: STRUCTURE UNSTABLE AT NODE nnnnn

DOF f

where: nnnnn

=

f

=

The node number at which instability was detected. The DOF number, as shown in the table below, in which there was found to be no resistance to displacement.

Sometimes in linear elastic analysis a modelling problem may manifest itself as gross linear or angular displacement. This kind of problem may not be obvious in the member force plots but may be evident in the plot of displaced shape. Modelling problems of this type can usually be fixed by the addition of one or more node restraints to inhibit the gross displacement. In non-linear analysis very large displacements can occur in the analysis of structures containing very flexible tension members. If displacements are sufficiently large the analysis will be terminated with a message of the form: EXCESSIVE DISPLACEMENTS

A solution can sometimes be obtained in cases like this by adjusting the analysis parameters but it is preferable to model very flexible tension members as cables. The above error message may also be obtained where the automatic deletion of tension-only bracing members during non-linear analysis renders a structure unstable.

General The CAD Interface is an integral part of MsTower that offers the capability of exporting 3-D data to a CAD system, forming the basis for a CAD drawing. This function is selected with the File > Export > CAD DXF command. Structure information is exchanged by means of an AutoCAD DXF. Note: You can use the Windows Paste command to transfer any part of an MsTower image into CAD.

Exporting a CAD DXF Each member center-line is represented by a single LINE entity in the DXF. The section shape may also be represented by a number of planes. The section shapes may be curtailed at member ends to avoid overplotting at the intersections. On selecting the File > Export > CAD DXF command the dialog box below is displayed.

CAD DXF EXPORT PARAMETERS The DXF contains only an Entities section without a drawing header. In AutoCAD, you may import the file with the "DXFIN" command and then use the "ZOOM E" command to fill the screen with the drawing. The limits may then be adjusted as required. You may suppress hidden lines and render the drawing in AutoCAD.

Exporting a Steel Detailing Neutral File Select File > Export > SDNF to create a file that can be imported into a steel detailing program that recognizes the SDNF format (e.g. Xsteel). The file will be created in the data folder with the name Job.SDN, where "Job" is the MsTower job name. At present, this command will transfer only the structural geometry and section sizes to the SDN file.

Windows Clipboard Operations MsTower facilitates use of the Windows clipboard for transfer of images to CAD programs by using the Enhanced Metafile Format (EMF) for the Windows clipboard when you select the View > Copy command. In programs such as AutoCAD, you can then use the Paste command to directly insert an image of the main MsTower view. Pressing the Print Screen key on the keyboard writes a Windows bitmap to the clipboard. Both of these formats may be pasted into Microsoft Word documents.

General This chapter describes the operation of the MSTower loading module in computing loads on the tower and ancillaries in accordance with the requirements of: BS 8100:Part 1 1986. BS 8100:Part 4 1995. CP3 Chapter 5. AS 3995-1994. Malaysian Electricity Supply Regulations 1990. EIA/TIA-222-F-1991. Loading types include dead load, ice load (with and without wind), node loads, wind loading on the structure, its ancillaries, feeders, and attachments, and temperature loads. Tower loading represented as node loads are computed for wind acting at any angle to the tower, with and without icing of members, as well as gravity loads due to self weight and icing. Additional node forces may be specified for any primary load case. Combination load cases may also be defined. Code partial safety factors may be specified directly or as factors in combination load cases. Tower Faces The faces of the tower are numbered 1, 2, 3 (and 4 for rectangular towers) in an anti-clockwise direction with face 1 normal to the positive X axis. The locations of face ancillaries are specified by reference to the face numbers. Towers With Cross-Arms Although the structure may have cross-arms, their presence is ignored when allocating members to faces and in the subsequent computation of wind loads. Additional face ancillaries should be added to the appropriate panels to account for the wind resistance of the cross-arms. The weight of the cross-arms and any encrusting ice is taken into account in DL and ICE load cases respectively.

The Tower Loading (TWR) File Data describing the tower loading is entered into a free-format text file called Job.TWR, where "Job" is the job name. A tower loading file may be generated by selecting Tower > Load Tower > Make Tower Loading File. A series of dialog boxes will be displayed for you to select the loading code and various parameters. The resulting TWR file will require some editing to customize it to the particular tower you are modelling. The data is organized into logical blocks: 1. Parameters block.

2. Terrain block. 3. Velocity profile block (optional). 4. Named node block (optional). 5. Guy list block (optional). 6. Loads block. 7. Panel block (optional). 8. Ancillaries block. Each block commences with a keyword identifying the block and terminates with the keyword END. The keyword EOF is used to terminate the file. Each data block is described in this chapter. More: Parameters Block Terrain Block Velocity Profile Block Named Node Block Guy List Block Loads Block Wind Load Cases Guyed Mast Patch Loadings Dead Loads Ice Loads Miscellaneous Loads Additional Node Loads Additional Member Temperatures Combination Load Cases Panel Block Ancillary Block

Parameters Block PARAMETERS ANGN an [CODE code] [ICE RO ro RW rw] [ALTOP alt] [PSF-V gamma-v] [PSF-M gamma-m] VB vb [{MEAN|GUST}] [OVERLAP n] [GRAV grav] [RHO rho] END

where: ANGN an CODE code

Keyword. The angle, in degrees, measured anti-clockwise from the X axis to geographic north. Keyword. Character string indicating the code rules to be followed in computing the wind and other loading: BS8100

Use the rules of BS 8100:Part 1 1986. BS8100P4

Use the rules of BS 8100:Part 4 1995. MER

Use the rules of the Malaysian Electricity Supply Regulations 1990 See note below. AS3995

Use the rules of AS 3995-1994. EIA222

Use the rules of EIA/TIA-222-F-1991.

ICE RO ro RW rw ALTOP alt

PSF-V

If omitted, the rules of BS 8100 Part 1 will be used. Unless specified otherwise all code references are to BS 8100. Keyword. Keyword. Radial ice thickness, mm or inches, in the absence of wind (Fig. 3.9 in BS 8100). Keyword. Radial ice thickness, mm or inches, in presence of wind (Fig. 3.9 in BS 8100). Keyword. Altitude of tower top, in m or ft. Used to determine basic ice thickness (Cl. 3.5.2 in BS 8100). Keyword.

gamma-v PSF-M gamma-m VB vb MEAN GUST OVERLAP n

GRAV grav

RHO rho

Partial safety factor on wind speed and ice thickness (Fig 2.1 in BS 8100). Keyword. Partial safety factor on design strength (Fig. 2.1 in BS 8100). Keyword. Basic wind velocity in m/sec or ft/sec (Fig. 3.1 in BS 8100). Keyword indicating that vb is the mean hourly wind speed. Keyword indicating that vb is the gust wind speed. Keyword. Overlap flag; 0 if overlap between bracing and leg members is not to be taken into account; 1 otherwise. If overlap is taken into account, the computed wind resistance will be smaller, but computation time will be marginally longer. Overlap will be taken into account if flag is omitted. Keyword. Gravitational acceleration in Z direction. If omitted, an acceleration of -9.81 m/sec² will be used in computing gravitational loads from masses. Keyword. Density of air at the reference temperature. If omitted, a value of 1.22 kg/m3 will be used.

Note: If code is specified as MER the following default values will be used unless otherwise specified: gamma-v = 1.0 gamma-m = 1.0 rho = 1.2 kg/m3 vb = 26.82 m/s

Terrain Block This block is used to specify the variation of terrain factor with wind direction around the tower. The data required depends on the loading code being used. The TERRAIN block for BS 8100 Part 1 is as follows: TERRAIN ANGLE angle TCAT tcat [Kd kd] [KR kr] [HH hh]... [BETAH betah] [XLEE xlee] ... END

where:

ANGLE angle TCAT tcat

KR kr KD kd

HH hh BETAH betah XLEE xlee

Keyword. Wind angle in degrees (clockwise) from geographic north. Keyword. Terrain category in Arabic numerals. Intermediate terrain categories may be given as a decimal, e.g. 2.5. Keyword. Terrain roughness factor. Interpolated from BS 8100 Table 3.1 if not specified. Keyword. Wind direction factor. Interpolated from BS 8100 Fig. 3.2 if not specified. If ice is present a maximum value of 0.85 will be used. Keyword. Height of hill above general terrain, in m or ft. Assumed to be zero if not specified. Keyword. Effective slope of hill , in degrees. Assumed to be zero if not specified. Keyword. Downwind distance from the crest of the hill to tower site, in m or ft. Assumed to be zero if not specified.

The TERRAIN block for BS 8100:Part 4 is as follows: TERRAIN ANGLE angle [SD sd] DSEA ds [XO xo HO ho HE he LU lu ... END

DTWN dt... X x]

where: ANGLE angle SD sd

DSEA ds DTWN dt XO xo HO ho

Keyword. Wind angle in degrees east of north. Keyword. Direction factor (BS 8100:Part 4 Cl. 3.1.5). If not specified a value will be interpolated from Table 1 of BS 8100:Part 4. If ice is present a maximum value of 0.85 will be used. Keyword. Distance from the sea, in km or miles. Keyword. Distance to edge of town in windward direction, in km or miles. Zero for country terrain. Keyword. Upwind spacing of permanent obstructions from mast, in m or ft. Keyword. General level of rooftops, in m or ft.

HE he

LU lu X x

Keyword. Effective height of topographic feature above general ground level in upwind direction, in m or ft. Keyword. Length of upwind slope in wind direction, in m or ft. Keyword. Horizontal distance of site from top of crest, in m or ft.

The TERRAIN block for AS 3995-1994 is as follows: TERRAIN ANGLE angle TCAT tcat [MD md H h LU lu X x] reg ... END

where: ANGLE angle TCAT tcat

MD md

H h LU lu

X x

reg

Keyword. Angle in degrees (clockwise) from geographic north. Keyword. Terrain category in Arabic numerals. Intermediate terrain categories may be given as a decimal, e.g. 2.5. Keyword. Wind direction multiplier. If not specified, a value will be interpolated from Table 2.2.5 of AS 3995. Keyword. Height of feature, in m or ft. Keyword. Horizontal distance upwind from the crest of the feature to a level half the height below the crest, in m or ft. Keyword. Horizontal distance upwind or downwind from the structure to the crest of the feature, in m or ft. Regional code A1, A2, A3, A4, B, C, or D, as defined in Fig. 2.2 of AS 3995.

No TERRAIN block is required for the Malaysian Electricity Supply Regulations. Terrain factors for up to eight directions may be entered. If necessary, intermediate values will be obtained by interpolation. If there is no variation in terrain with angle, enter a single set of values for angle zero. The TERRAIN block may be omitted, in which case a terrain category of 1 will be assumed (tcat = 1). The TERRAIN block will be ignored if a user defined velocity profile is specified.

Velocity Profile Block This optional block may be used to specify a velocity profile that takes precedence over any profile that may be computed from the code terrain rules. VELOCITY ZF z VF vfact ... END

where: ZF z VF vfact

Keyword. Height above ground level at which velocity factor is specified, in m or ft. Keyword. Velocity factor at height z. The actual velocity is: Vz = Vb × gamma-v × vfact

The velocity profile should be entered in increasing order of height. Additional wind profiles may be defined for determining patch loads on masts: PVEL_MAST ZF z VF vfact ... END PVEL_GUY ZF z VF vfact ... END

If PVEL_MAST and PVEL_GUY blocks are defined a number of "patch" load cases will be generated as described in this chapter.

VELOCITY PROFILE

Named Node Block Up to 40 nodes may be "named" by being assigned an alphanumeric tag: NODELIST [ZREF {zr|top|btm}] name X x Y y Z z ... END

where: ZREF zr TOP BTM name

X x Y y Z z

Keyword. Z coordinate of the origin of the nodes in the following list of nodes, in m or ft. Keyword indicating that Z coordinate of the origin is the top of the tower. Keyword indicating that Z coordinate of the origin is the base of the tower. An alphanumeric string of characters. It is limited to 8 characters and must not be recognizable as a number. Keyword. X coordinate of the node, in m or ft. Keyword. Y coordinate of the node, in m or ft. Keyword. Z coordinate of the node, relative to the origin defined by ZREF, in m or ft. If ZREF has not been defined the Z coordinate will be relative to the global origin.

The node list establishes node number aliases that may replace a node number anywhere in the TWR file. The aliases may be useful where modifications to the geometry results in node numbers changing, for example, when the tower is being studied for strengthening or a number of different bracing patterns are being considered. If a family of transmission towers is being designed the node list could define the loading points with only the ZREF parameter being changed as extensions are added.

Guy List Block This optional block allows you to group a number of guys together and to refer to them by name when considering asymmetrical ice loading in ice and wind load cases. Up to eight lists of guys may be input: GUYLIST name g1 ... gn ... END

where: name

g1..gn

An alphanumeric string of characters. It is limited to 8 characters and must not be recognizable as a number. List of member numbers for the guys in this list.

A particular guy may belong to more than one list. Note: You may obtain the member number for a guy from the data tip that appears when the cursor is placed on it, with the Query > Member Data command, or by double-clicking on it.

Loads Block This block describes the load cases that are to be computed. Each primary load case consists of a CASE description, a specification for a wind, dead, or ice load, and optionally, additional node loads that are to form part of that load case. Combination load cases consist of a CASE description and a number of load case references and factors. All loads on the tower should be described in the LOADS block. LOADS CASE ... Wind, dead, ice, or miscellaneous load Additional node loads Additional member temperatures CASE ... Wind, dead, ice, or miscellaneous load Additional node loads Additional member temperatures ... CASE ... Combination load case ... END

Each load case must start with the line: CASE

lcase

title

where: lcase title

1-5 digit load case reference number. Load case title up to 50 characters.

Wind Load Cases WL

{ANGLE wangn | ANGLX wangx} [{ICE|NOICE}]... [BARE] [CROSS] [{PATCH|NOPATCH}] [SMEAR] [UNICE list]

where: ANGLE wangn ANGLX wangx ICE NOICE BARE

CROSS

PATCH NOPATCH SMEAR

UNICE list

Keyword. Angle in degrees (clockwise) from geographic north. Keyword. Angle in degrees (anti-clockwise) from the global X axis. Keyword indicating that ice is to be considered for this case. Keyword indicating that ice is not to be considered for this case. Keyword indicating that wind load is to be computed for the bare tower, i.e., the tower without any ancillaries. Keyword indicating that MSTower is to generate sub-load cases in the cross wind direction. Keyword indicating that patch load cases will be generated for guyed masts. Keyword indicating that patch load cases will not be generated for guyed masts. Keyword indicating that patch wind load on guys will be "smeared" over the length of the guys according to the rules of ENV1993-31:1997, Para A.4.3.2.3. Keyword. Name of a guy list defined in the GUYLIST block. The guys nominated in this list will have wind loads applied to the bare guy, not to the iced diameter of the guy.

If the MEAN wind speed is being used the basic wind load case lcase contains the loads due to the mean hourly wind applied to the equivalent bare tower. This is followed by sequentially numbered sub-cases, the first containing the fluctuating component of the wind load on the large ancillaries, and the second the sum of the mean hourly loads on the tower and ancillaries. The CROSS wind load cases are required additional sub-cases containing the loads due to cross-wind on the equivalent bare tower and the fluctuating component of the cross-wind on the ancillaries are generated. If the GUST wind speed is being used, the along-wind loads on the large ancillaries are accumulated into the basic wind load case and no additional sub-loads are formed. You must leave gaps in the numbering of wind load cases to accommodate the sub-cases; a difference of ten between successive cases is sufficient and convenient.

Guyed Mast Patch Loadings For a guyed mast, the program will generate a set of patch load sub-cases as defined in BS 8100:Part 4 Cl. 5.3.2.2. These are: 1. On each span of the mast column between adjacent guy levels (and on the span between the mast base and the first guy level). 2. Over the cantilever, if relevant. 3. From midpoint to midpoint of adjacent spans. 4. From the base of the mid-height of the first guy level. 5. From the mid-height of the span between the penultimate and top guy to the top guy if no cantilever is present, but including the cantilever, if relevant. For BS 8100, the patch loads are derived from equivalent velocity profiles derived from the equations in Cl. 5.3.2.2 and Cl. 5.3.2.3 for the mast and guy, respectively. For AS 3995, the mean hourly wind profile is used with segments of gust wind profile forming the load patches. If patch loads are not required, the wind profile specified in the PARAMETERS block will be used. If specified, the various wind profiles needed to form patch load cases will be obtained as follows: VELOCITY

Mean wind profile. Patch wind profile on mast. Patch wind profile on guys.

PVEL_MAST PVEL_GUY

Formation of patch sub-cases may be prevented by using the keyword. NOPATCH when specifying the wind load. If patch loading is specified, you must leave a sufficient gap in the numbering of successive wind load and combination load cases to accommodate the sub-cases that will be generated.

Dead Loads DL

[BARE]

where: DL

BARE

Keyword signifying a dead load case. The weight of all ancillaries will be included in the load case. Keyword. If present, the dead load is computed

for the tower structure only, without ancillaries.

Ice Loads ICE

DENS dens

{WIND|NOWIND}

[BARE]

[UNICE list]

where: ICE

DENS dens WIND NOWIND BARE UNICE list

Keyword signifying a gravity load due to icing of the tower. The weight of ice coating structural members and ancillaries will be taken into account. Keyword. Specific weight of ice, in kN/m3 or lb/ft3. Keyword indicating presence of wind. Keyword indicating absence of wind. Keyword indicating that ice load is computed for the tower structure only without ancillaries.. Keyword. Name of a guy list defined in the GUYLIST block. The guys nominated in this list will not have ice applied.

Miscellaneous Loads Load cases not falling into one of the above categories may be included as miscellaneous loads. These could include construction, maintenance, or similar loads. MI NDLD ...

list

FX fx

FY fy

FZ fz

where: MI NDLD..

Keyword. See "Additional Node Loads", below.

Additional Node Loads

Additional node loads may specified for any wind load, dead load, or ice load case. NDLD

list

FX fx

FY fy

FZ fz

where: NDLD

Keyword. The nodes to which the forces are to be applied, in one of the following forms:

list

n1 n2 ... nn

A list of node numbers. n1 TO n2 INC n3 Includes n1 to n2 in

steps of n3.

ALL

All nodes. Keywords indicating direction of force. fx fy fz Forces in the global X, Y, Z directions, respectively, in kN or kips. FX FY FZ

Additional Member Temperatures Additional member temperatures may be specified for any wind load, dead load, or ice load case. MTMP

list

TEMP

t

where: MTMP list

Keyword. The members to which the temperatures are to be applied, in one of the following forms: m1 m2 ... mn

A list of node numbers. m1 TO m2 INC m3 Includes m1 to m2 in

steps of m3.

ALL TEMP t

All members. Keyword. Centroidal temperature. Transverse temperature gradients will be set to zero.

In addition to being used to model the effects of temperature change, MTMP loads may be used to simulate a broken guy, by specifying a temperature increase sufficient to make the guy slack.

Combination Load Cases COMBIN ...

lcase

factor

where: COMBIN lcase

factor

Keyword. Load case reference number. This must be a load case reference numbers specified in a CASE record do not refer to sub-cases generated for groups of large ancillaries or crosswinds or patch load cases. Factor by which the loads in lcase are to be multiplied. The factor may be used to apply different partial safety factors on dead load or ice densities to the primary load cases that are being combined.

Panel Block The panels into which the tower is divided are defined by listing nodes at the panel boundaries in order from the top of the tower. The Z coordinates of these nodes will be used when determining the panel to which projected areas of member and ancillaries are allocated. The list of nodes may extend over one or more lines. If the PANEL block is not specified panel heights will be obtained from the Job.TWM file, generated by the tower builder. The PANEL block is not usually required.

Ancillary Block This block is used to describe the ancillaries attached to the tower. Data for each ancillary is given on a separate line as a series of keywords and numeric items. Ancillary libraries, containing the dimensions and other properties of ancillaries, are used to reduce the amount of data required. Ancillaries are sub-divided into the following types: Linear ancillaries. Face ancillaries. Large ancillaries. Insulators

ANCILLARIES

ANCILLARY AXES More: Linear Ancillaries Face Ancillaries Large Ancillaries Insulators

Linear Ancillaries Linear ancillaries are items such as wave-guides, feeders and the like. Usually they are either attached to the face of the tower or contained within the body of the tower. The following data is required: LINEAR LIB libr name XB xb YB yb ZB zb [XT xt] [YT yt] ZT zt ... [SELF] LIB lname [FACT fact] [SHADE shade] ... [SHADY shady] ANG anga ...

where: LINEAR LIB libr

name XB xb YB yb ZB zb XT xt

YT yt

ZT zt

SELF

LIB lname FACT fact SHADE shade SHADY shady

Keyword. Keyword. Name of library containing linear ancillaries. It is assumed that the library is located in the data folder unless the name is prefixed with "P:" or "L:". "P:" indicates that the library is in the program folder and "L:" indicates that it is in the library folder. Identifier for the ancillary, 1-16 characters, not recognizable as a number. Keyword. X coordinate of the base of the ancillary, in m or ft. Keyword. Y coordinate of the base of the ancillary, in m or ft. Keyword. Z coordinate of the base of the ancillary relative to the base of the tower, in m or ft. Keyword. X coordinate of the top of the ancillary, in m or ft. If not entered, the X coordinate of the base of the ancillary is used. Keyword. Y coordinate of the top of the ancillary, in m or ft. If not entered, the Y coordinate of the base of the ancillary is used. Keyword. Z coordinate of the top of the ancillary relative to the base of the tower, in m or ft. This value must be entered. Keyword indicating that the linear ancillary is self-supporting. The mass of the ancillary will be allocated to panels when computing the equivalent static factor but its self weight will not be added to the tower when computing DL cases. If omitted, the weight of the ancillary will be added to that of the tower. Keyword. Name of ancillary in library 1-16 characters. Keyword. Number of ancillaries of this type at this location. Keyword. Coefficient used to factor exposed area of a linear ancillary. Keyword. Coefficient used to factor exposed area of linear ancillaries for wind the "y" direction.

ANG ang

Keyword. Angle between the "x" axis of the ancillary and the X axis of the tower measured clockwise from the X axis.

Face Ancillaries These are ancillaries mounted on the faces of the tower and consisting of small items whose wind resistances will be added to that of the panel of the face to which they are attached. FACE name FACE flist ZA za MASS mass AREA area AICE aice {FLAT|CYL} ...

CN cn ...

where: FACE name FLIST flist

ZA za MASS mass CN cn AREA area AICE aice

FLAT CYL

Keyword. Identifier for the ancillary 1-16 characters, not recognizable as a number. Keyword. List of faces to which ancillaries of this type are attached, as a concatenated string of the digits 1, 2, 3, and 4, with no embedded spaces, e.g. 13 means the ancillaries are on faces 1 and 3. Keyword. Z coordinate of the mounted level of the ancillary, in m or ft. Keyword. Mass of the ancillary, in kg or lb. Keyword. Drag coefficient for wind normal to the face to which the ancillary is attached. Keyword. Projected area of the ancillary on the face of the tower, in m2 or ft2. Keyword. Surface area that can be coated with ice, in m2 or ft2. The volume of ice is obtained by multiplying this area by the thickness of ice. Keyword indicating that the ancillary is to be considered as sharp edged. Keyword indicating that the ancillary is to be considered as cylindrical.

Large Ancillaries These are discrete ancillaries too large to be considered as "face-mounted" ancillaries, usually positioned on the face of the tower or external to the tower. Large ancillaries are described: LARGE LIB libr name XA xa YA ya ZA za LIB lname ... [FACT fact] [SHADE shade] ANG ang ... [{AMASS|TMASS}] [ATTACH nlist] ...

where: LARGE LIB libr

name XA xa YA ya ZA za

LIB lname FACT fact

SHADE shade ANG ang

AMASS TMASS mass

Keyword. Keyword. Name of library containing large ancillaries. It is assumed that the library is located in the data folder unless the name is prefixed with "P:" or "L:". "P:" indicates that the library is in the program folder and "L:" indicates that it is in the library folder. Identifier for the ancillary 1-16 characters, not recognizable as a number. Keyword. X coordinate of the ancillary, in m or ft. Keyword. Y coordinate of the ancillary, in m or ft. Keyword. Z coordinate of reference level of the ancillary relative to the base of the tower, in m or ft. If an antenna, the reference level is usually the center of radiation. Keyword. Name of ancillary in library 1-16 characters. Keyword. Factor by which the library dimensions and areas of the ancillary are multiplied. If not given, a value of 1.0 is used. Keyword. Coefficient used to factor exposed area of a large or linear ancillary. Keyword. Bearing of the ancillary, the clockwise angle between north and the negative "x" axis of the ancillary. Keyword. Keyword. Mass, in kg or lb, with the following meanings

ATTACH nlist

depending on which keyword it follows: AMASS Additional mass, to be added to the library mass. TMASS Total mass, to be used instead of the mass in the library. Keyword. List of nodes to which the ancillary is attached. If attachment data is omitted, the program will allocate the forces from the ancillary to leg nodes closest to the level of the ancillary. The forces of the ancillary will be transferred into the tower by a statically equivalent set of forces on the listed nodes.

An ampersand, "&", may be used at the end of a line to indicate that the data for an ancillary extends to the next line. If the mean wind speed is being used, the gust factor for each large ancillary will be computed and the product of the gust factor and the mean hourly loads will be accumulated to form a single sub-load case for each wind load case.

Insulators These may be used to separate sections of a multi-segment guy. They are described as: INSULATORS name NODE node AREA area MASS mass CN cn ...

AICE aice ...

where: INSULATORS name NODE node AREA area

AICE aice

MASS mass CN

Keyword. Identifier for the insulator 1-16 characters, not recognizable as a number. Keyword. Node number at which the insulator is located. Keyword. Projected area of the insulator, in m2 or ft2. It is assumed that the projected area is the same for all angles of wind incidence. Keyword. Surface area that can be coated with ice, in m2 or ft2. The volume of ice is obtained by multiplying this area by the thickness of ice. Keyword. Mass of the insulator, in kg or lb. Keyword.

cn

Drag coefficient, assumed to be the same for all angles of wind incidence.

Note: You may obtain the node number for an insulator from the data tip that appears when the cursor is placed on it, with the Query > Node Data command, or by double-clicking on it.

Output The following tables of intermediate results computed by the loading module are written to a loading log file and may be viewed by selecting the File > List/Edit > Loading Log command or printed by selecting the File > Print > Loading Log command. Velocity Table The input and computed parameters used in computing the velocity profile and the variation of velocity with height above the base of the tower are reported. Member/Face Table Each member is allocated to a tower face and its projected length in the face is reported. Leg members will belong to two faces while internal members, such as hip and plan bracing, will not belong to any face. The length of bracing members that intersect leg members is adjusted for the overlap between the IP and the edge of the leg member if the overlap flag in the PARAMETERS block is set to 1. Face Results The area of each panel, its solidity ratio, and drag coefficient, the resistance of ancillaries, shielding factor, Sf, and the normal resistance of the face as a single frame are reported for each face. Resistance Table The effective resistance, Re1 and Re2, and the total wind resistance, Rwt, for the specified wind angle are reported, along with the total mass (structural and ancillary) of each panel. The factor determining whether the equivalent static method is valid is also reported.

Method The program uses the procedures set out in Section 4.4 of BS 8100 for the computation of resistances. If the mean-hourly wind speed is being used and if large ancillaries are specified in a wind load case, the wind loads on the equivalent shielded tower will be computed and additional sub-load cases will be generated for each wind direction for the large ancillaries. This case will contain the sum of the gustfactored wind loads on the large ancillaries.

If the gust wind speed is being used, the loads on the equivalent shielded tower and large ancillaries are computed separately and added together to form a single load case before being output. More: BS 8100 CP3 Chapter 5 AS 3995 Malaysian Electricity Supply Regulations 1990 EIA/TIA-222-F BS 8100 Gust Factor Correction

BS 8100 The velocity, VB, should be specified as MEAN. MsTower uses the general method of BS 8100 for computing the wind resistance of towers. This method allows for towers with faces that are asymmetrical, either structurally or due to their complement of ancillaries. It also allows the resistance to be computed for any wind incidence angle. When using the general method, the resistance of the single frame comprised in each face is computed, along with shielding factors and Kth. The resistance of the complete tower is built up from these values. Methods of computing drag coefficients of panels made of flat and circular sections (both sub-critical and super-critical) are also given. BS 8100 also uses a simpler method for symmetrical towers, whereby the resistance for the complete tower can be determined from drag factors for the overall tower. If a panel contains ancillaries, the projected area of the ancillary is used when computing panel solidity ratios and single panel drag coefficients. The wind forces on the ancillary are then computed using the drag coefficients from the ancillary library and a statically equivalent set of node loads is applied to the nodes to which the ancillary is attached.

CP3 Chapter 5 The velocity, VB, should be specified as GUST. When wind loading to CP3 Ch. 5 is to be calculated, the wind load code entry should be left blank and the three second gust wind speed should be specified. It is also necessary to define a wind velocity profile in a VELOCITY block as no equation is given for this in CP3 Ch. 5. In the absence of a VELOCITY block the velocity profile in BS 8100 will be used.

AS 3995 The velocity, VB, should be specified as GUST. When AS 3995 is specified, MsTower uses the general method as described above but with single frame drag coefficients that give overall drag coefficients equal to those in Table 2.2.8.2 of AS 3995. This allows the program to maintain the ability to deal with towers that are asymmetrical or composed of mixed section shapes. It also allows wind forces to be computed for angles of incidence other than face and corner. For a tower carrying large dishes, the critical wind may occur at some other angle, which may vary from member to member. If loads are being computed for a mast, MsTower will use code-defined mean and gust wind profiles in computing patch load cases.

Malaysian Electricity Supply Regulations 1990 If the code in the PARAMETERS block is specified as MER (Malaysian Electricity Supply Regulations), the program uses the formulae and methods of BS 8100, but with the following differences: Wind velocity is constant over the full height of the tower. A velocity equal to the product of the basic wind velocity and the partial safety factor on wind speed is used. A solidity ratio of 0.1 is used to determine the single frame drag coefficient (BS 8100 Fig. 4.5). When used with the wind velocity specified in the regulations this gives a wind pressure of 810 N/m2 on the projected area of a face made up of flat sided members. The effective shielding factor in C1.4.4.1 of BS 8100 is taken as 0.5, giving an additional 405 N/m2 on the leeward face.

EIA/TIA-222-F The wind velocity, VB, should be the fastest mile wind speed. No modifying keyword (MEAN or GUST) is required. Unless a user defined profile is used, the velocity profile will be computed in accordance with Cl. 2.3.3. A TERRAIN block is not required. When EIA222 is specified, MSTower uses the general method as described above but with modifications to coefficients that give overall drag coefficients equal to those derived from Section 2.3 of EIA/TIA-222-F for the wind directions specified in Table 2. This allows the program to maintain the ability to deal with towers that are asymmetrical or composed of mixed section shapes. It also allows wind forces to be computed for any incidence angle instead of just face and corner wind. For a tower carrying large dishes, the critical wind may occur at some other angle, which may vary from member to member.

All wind loads, including any NDLD forces specified in a WL case, are multiplied by a gust response factor determined in accordance with Cl. 2.3.4. MSTower is unable to compute patch loading for EIA-222 unless specific velocity profile tables are entered.

BS 8100 Gust Factor Correction If BS 8100:Part 1 is specified with a mean hourly wind speed, each wind load case will consist of: 1. A load case containing forces on the equivalent bare tower due to the mean wind. 2. A sub-load case containing forces on the large ancillaries due to the mean wind multiplied by the gust factor appropriate to each ancillary's size and height above ground level. 3. A sub-load case containing the sum of the mean wind loads on the tower and ancillaries. MSTower computes and applies gust factors to member forces for the cases of wind on the bare equivalent tower, adds in the member forces due to gust wind on the ancillaries, and then recomputes the combination cases. Note: The above applies only where mean wind speeds are used. If gust wind speeds are used the loads on large ancillaries will be computed separately and added to the loads on the equivalent bare tower before output. No additional sub-cases will be produced.

Ancillary Libraries Ancillary libraries are text files containing blocks of data giving the dimensions and drag characteristics of ancillary items. Separate libraries are used for large ancillaries and linear ancillaries. The libraries remain text files and unlike the section library, do not require further processing before use. The libraries supplied with MsTower are called Lin.LIB and Anc.LIB. Because of the wide variety of ancillaries, there is no doubt that you will have to add additional information to the libraries. It is recommended that the distribution libraries are not modified. Instead, for each project, you may copy the distribution versions to libraries with names of your choice. All changes should then be made to the project libraries. Note: Ancillary libraries use metric units. The structure of an ancillary library file is: ANCILLARY

... END COEFFICIENTS

...

END

More: Large Ancillary Library Linear Ancillary Library Drag Coefficients

Large Ancillary Library The ANCILLARY block in the large ancillary library contains the following data for each ancillary type: name coeff dim mass af asf aice zref xcg xicg... fcx fcy fzm ishape

where: name coeff

dim

mass

Name by which the antenna is referenced in the TWR file. Name of set of coefficients to be used in calculating the projected area and wind resistance of the antenna. Reference dimension, in m, normally the dish diameter, used in computing forces and moments about the antenna axes and the BS 8100 gust factor for the antenna. Mass of the ancillary, in kg.

af

Frontal area of the antenna, in m2.

asf

Side area of antenna, in m2. This will be used to compute the projected area of the antenna at different angles if the projected area coefficients are zero. In this case, the projected area will be computed as: af × cos²(angle) + asf × sin²(angle) Surface area of a the antenna that may be coated with ice, in m2. Used in computing the weight of ice on an iced antenna. Z dimension from the antenna origin for wind loads and the level of the antenna in the TWR file, in m. Usually, either the centerline of radiation or the mounting level of the antenna. Horizontal offset from the antenna origin to the center of gravity of the un-iced antenna, in m. Horizontal offset from the antenna origin to the center of gravity of a uniform ice coating on the antenna, in m. Correction factor to be applied to drag

aice

zref

xcg xicg

fcx

fcy

fzm

ishape

coefficient for drag force along the axis of the antenna. Correction factor to be applied to drag coefficient for horizontal drag force normal to the axis of the antenna. Correction factor to be applied to drag coefficient for yawing moment (twisting about the vertical axis of the antenna). Shape code for the antenna, used to select a symbol for plotting.

The drag coefficients are contained in the ancillary library in a separate COEFFICIENTS block, which may contain any number of sets of coefficients: COEFFICIENTS coeff FACT fact ang afact Cfx Cfy ... END

Cfz

Cmx

Cmy

Cmz

where: coeff FACT fact

ang afact

Cfx Cfy Cfz Cmx Cmy Cmz

Name of set of drag and projected area coefficients. Keyword. Factor by which the coefficients in the table must be multiplied so that when used with kg and meter units, the resulting forces and moments will be in N and N.m. Angle of wind incidence for which drag coefficients apply. Area angle factor. The projected area on a plane normal to the angle of wind incidence is obtained as: af × afact Coefficient for drag along the "x" axis of the antenna. Coefficient for side force along the "y" axis of the antenna. Coefficient for lift force along the "z" axis of the antenna. Coefficient for moment about the antenna "x" axis, i.e. the rolling moment. Coefficient for moment about the antenna "y" axis, i.e. the pitching moment. Coefficient for moment about the antenna "z" axis, i.e. the yawing moment.

The forces and moments at the origin of the antenna are given by: Fx= 0.5

× Cfx × Af × V2

Fy= 0.5

× Cfy × Af × V2

Fz= 0.5

× Cfz × Af × V2

Mx= 0.5

× Cmx × dim. × Af × V2

My= 0.5

× Cmy × dim. × Af × V2

Mz= 0.5

× Cmz × dim. × Af × V2

where "dim." is a lever-arm. If necessary, the coefficients for the angle of wind incidence are interpolated from the coefficients table. All dimensions and forces for an antenna are measured in the ancillary axes, a set of right-handed orthogonal axes (see diagram in Ancillary Block).

Linear Ancillary Library The ANCILLARY block in the linear ancillary library contains the following data for each ancillary: name

coeff

mass

af

asf

where: name coeff

mass af asf

aice

shape

Name by which the antenna is referenced in the TD file. Name of set of drag curves to be used for the antenna. Use NONE if the standard drag coefficients given in BS 8100 are to be used. Mass of the ancillary per unit length, in kg/m. Frontal are of the antenna, in m²/m. Side area of antenna. This will be used to compute the projected area of the antenna at different angles if the projected area coefficients are zero. In this case, the projected area will be computed as: af × cos²(angle) + asf × sin²(angle) Surface are of the antenna that may be coated with ice, in m²/m. Used in computing the weight of ice on an iced antenna. An integer code indicating the ancillary shape, used in computing the thickness of ice coating: 0 = Cylindrical. 1 = Sharp-edged flat section.

Drag Coefficients

The drag coefficients are contained in the ancillary library in a separate COEFFICIENTS block, which may contain any number of sets of coefficients: COEFFICIENTS coeff FACT fact ang afact Cfx Cfy ... END

where: coeff FACT fact

ang afact

Cfx Cfy

Name of set of drag and projected area coefficients. Keyword. Factor by which the coefficients in the table must be multiplied so that when used with kg and meter units, the resulting forces and moments are in N and N.m. Angle of wind incidence to which drag coefficients apply. Area angle factor. The projected area on a plane normal to the angle of wind incidence is obtained as: af × afact Coefficient for drag along the "x" axis of the ancillary. Coefficient for side force along the "y" axis of the ancillary.

The forces and moments at the origin of the ancillary are given by: FX= 0.5

× Cfx × Af × V²

FY= 0.5

× Cfy × Af × V²

If necessary, the coefficients for the angle of wind incidence are interpolated from the coefficients table. All dimensions and forces for an antenna are measured in the ancillary axes, a set of right-handed orthogonal axes (see diagram in Ancillary Block).

General Graphics Input is the most efficient input method of inputting a user defined panel. It involves "drawing" a structure on the screen using the mouse or keyboard, and it includes many simple graphical operations, such as copying, moving, rotating, sub-dividing, and erasing. More powerful graphical operations include intersection, extrusion, and transforming coordinates. In effect, MsTower's graphical input capability is an intelligent CAD system customized for the task of entering structure data.

GRAPHICS INPUT Many MsTower users have found that the few hours required to become proficient at graphical input have been be well rewarded by vastly increased productivity in creating and editing UDPs.

Basic Drawing Graphics Input is started by selecting Tower > Build Tower > User Defined Panels > Graphics Edit. You will also be in Graphics Input mode when you import an existing UDP by selecting Tower > Build Tower > User Defined Panels > UDP To Graphics. To start drawing a UDP, click on the toolbar button. This is the same as selecting the Structure > Draw command from the main menu. Notice the tooltip "Draw Members" that appears when the mouse Members cursor crosses this button. As you initiate the Draw command several things happen: 1. The toolbar button displays in the depressed state, indicating that MsTower is in DRAW mode. 2. "DRAW" is displayed in the status bar at the bottom of the MsTower window. 3. The prompt area of the status bar (on the left) displays the instruction "Click on first point or enter coordinates". 4. The cursor becomes a cross. You may now click anywhere in the main window or enter coordinates from the keyboard to locate the "A" node of the first member. Notice that once the first point is specified the prompt changes to "Click on end point or enter coordinates; press SPACE BAR to break line". Select another point and you will have drawn the first member. This point is the "B" node of the first member and the "A" node of the next member. You

may continue selecting points to define new members. Keyboard Entry of Coordinates There are many situations where the most convenient way to enter a new node is to type the coordinates. As soon as you start to type, a dialog box appears to accept your input.

DIALOG BOX FOR ENTERING COORDINATES Coordinate Systems You may input coordinates in rectangular, cylindrical, or spherical coordinate systems, using standard syntax or AutoCAD syntax. The format of the coordinate string is described below for each syntax. STANDARD SYNTAX Rectangular coordinates "X Y Z", where "X", "Y", and "Z" are respectively, the X, Y, and Z coordinates of the point. Cylindrical coordinates "C radius theta h", where "radius", "theta", and "h" are respectively, the radius, horizontal angle, and height of the point. Spherical coordinates "S radius theta phi", where "radius", "theta", and "phi" are respectively, the radius, horizontal angle, and vertical angle of the point. Trailing zero coordinates do not have to be entered. For example, the point (3,0,0) may be entered as "3". Coordinates must be separated by a space or a comma. Coordinates relative to the last point are preceded by "R" or "r". No separator is required after the "R" or "r". AUTOCAD SYNTAX Rectangular coordinates "X Y Z", where "X", "Y", and "Z" are respectively, the X, Y, and Z coordinates of the point. Cylindrical coordinates "radius < theta h", where "radius", "theta", and "h" are respectively, the radius, horizontal angle, and height of the point. The last two values must be separated by a space or a comma. Spherical coordinates "radius < theta < phi", where "radius", "theta", and "phi" are respectively, the radius, horizontal angle, and vertical angle of the point. Coordinates relative to the last point are preceded by "@". No separator is required after the "@". Breaking the Line Press the space bar or right-click and choose Break Line on the context menu. Notice that the cursor, the status bar, and the button show that MsTower is still in Draw mode. You may now click a new node that is not connected to the last by a member.

Ending the Line Right-click and choose End Line on the context menu. Notice the cursor change to the standard arrow. This indicates that the command is finished. The status bar and the button also show that MsTower is no longer in Draw mode.

The Drawing Snap Mode Initially, the status bar displays NONE for the snap mode. This means that the coordinates of any node defined by clicking the mouse will be indeterminate to some extent, because the degree of accuracy with which you can position the mouse is limited. Practically, therefore, the snap mode NONE is rarely used. The first few nodes are usually specified by grid points or entry of coordinates. Thereafter, the Mid/End snap mode is usually used. Grid Snap Mode (GRID) In Grid mode the status bar displays GRID. Grid spacing is initially 1 unit in each global axis direction but you may change it with the Structure > Drawing Settings > Grid Spacing command. When the grid is displayed the cursor snaps to the nearest grid point. Thus, with the mouse, you can only draw members from one grid point to another. Enter coordinates to specify a point that is not on the grid. Mid/End Snap Mode (MEND) When drawing in this mode the cursor snaps to a nearby member end or mid-point. Most graphical input is done in this snap mode. When starting a new structure you cannot enter Mid/End snap mode because there are no members to snap to. Intersection Snap Mode (INTR) When drawing in this mode the cursor snaps to a nearby intersection of two or more members. A new node is automatically introduced at the intersection point if there is not already a node there. When starting a new structure you cannot enter Intersection snap mode until there are at least two members. Perpendicular Snap Mode (PERP) In this mode the cursor snaps to the point on a target member that makes the new member perpendicular to the target member. When starting a new structure you cannot enter Perpendicular snap mode until there is at least one member. Orthogonal Snap Mode (ORTH) In this mode you can only draw members in a global axis direction. Nearest Snap Mode (NEAR) In this snap mode the cursor snaps to the point on a target member that is nearest to the cursor location. Changing the Snap Mode "On the Fly"

A very convenient feature is the ability to change the snap mode during a draw operation. For example, you may click the start point of a new member at the end of another while in Mid/End snap mode and then change to Grid snap mode to select the end point. Right-click to display the context menu with its selection of snap modes (see diagram at the beginning of this chapter).

The Drawing Plane The drawing plane is a plane on which nodes are located when you draw in either the Grid or NONE snap modes. For example, when drawing in Grid snap mode with default settings, the drawing plane is X-Y at an offset of zero along the Z axis. This means that all new nodes drawn in Grid or null snap mode have a Z coordinate of zero. Changing the view with any of the Front View, Back View, Right View, Left View, or Top View commands automatically changes the drawing plane so that it is parallel to the view plane. Use the Structure > Drawing Settings > Drawing Plane command to change the drawing plane as required. If you change the view or the drawing plane so that it (the drawing plane) is at right angles to the view plane (the plane of the screen) you may see the warning message shown below and you may not be able to click a new point.

WARNING THAT DRAWING PLANE IS PERPENDICULAR TO SCREEN

Automatic Removal of Duplicate Nodes and Members At various stages during graphical input operations, MSTower removes any duplicate nodes or members that are detected. The first node or member to be drawn will remain and any that are superimposed will be removed automatically. This behaviour has two significant consequences: Overlapping nodes and members in copy operations are ignored. In drawing members, you may draw over an existing member instead of breaking the line.

Cursors MSTower displays various cursors at different times, depending upon what is happening. These cursors are shown below:

Cursor Description Command mode. MSTower is waiting for you to select a command from the menu, click a toolbar button, or select a node or member (the cursor changes as soon as you select a node or member). Drawing mode. MSTower is waiting for you to click an end of a member. Look at the right of the status line to determine which snap mode is in effect. You may use the Structure > Drawing Settings command or the context menu to change the snap mode without leaving the current drawing command. Member selection mode. MSTower is waiting for you to select one or more members by clicking on them or enclosing them in a selection box. If you drag a selection box from left to right, cut members are excluded. Dragging from right to left includes cut members. Node selection mode. MSTower is waiting for you to select one or more nodes by clicking on them or enclosing them in a selection box. This cursor appears when you are selecting a zoom window or panning. When zooming, drag from one corner to the diagonally opposite corner of the rectangle you want to zoom to. When panning, click on any part of the structure and drag to the new location for that part. Generally, when you have finished a command, MSTower allows you to repeat the command until you cancel the command by right-clicking. For example, when you select the Structure > Erase Members command, the cursor changes, you then select members you want to erase and confirm the selection by right-clicking and choosing OK on the context menu. The member selection cursor is still displayed, allowing you to choose more members to erase. To terminate the command, right-click, and the standard arrow cursor will reappear. Many commands are interruptible. This permits you to adjust the view during a command. When drawing members in a large model, for example, having clicked the "A" node of a member, you may need to zoom in to another region of the structure before clicking the "B" node.

Shortcut Keys MSTower permits the use of shortcut keys to some commands. Shortcut keys are also known as accelerator keys. Below is a complete list of MSTower's shortcut keys: Shortcut Ctrl+C Ctrl+X Ctrl+V Ctrl+Z

Command Copy Cut Paste Undo

Ctrl+Y F5 Ctrl+A Delete Home

Space

Redo Redraw Select All Erase Members Zoom Extents/Limits Viewpoint Left Viewpoint Right Viewpoint Up Viewpoint Down Break Line

The effect of pressing a shortcut key depends on the context. For example, pressing Delete usually deletes selected members, but in a dialog box it may delete text.

Selecting Nodes and Members In MSTower, when you choose a command, you usually select the nodes or members that are the object of the command. This may be done in several ways: Clicking each node or member in turn. Clicking again on a node or member deselects it. Dragging a selection box that encloses the nodes or members to be selected. "Dragging a selection box" means clicking (with the left mouse button) a point away from the nodes or members to be selected, then dragging the mouse until the selection box encloses the necessary nodes or members, and finally, releasing the left mouse button. Note that when the selection box is dragged from right to left, a "crossing window" appears, which selects not only members enclosed by the box but also members cut by the sides of the box. Clicking a selection box. This is similar to dragging a selection box but instead of clicking, dragging, and releasing the mouse button, you click two points to define diagonally opposite corners of the selection box. All members may be selected by Ctrl+A (see "Shortcut Keys", above). In all cases, you confirm the selection by right-clicking and choosing OK on the context menu.

Right-Clicking on Nodes and Members MSTower fully implements the Windows protocol for right-clicking on objects to obtain a pop-up of related commands. This provides an alternative method of operation: 1. Select node(s) or member(s).

2. Right-click to choose required operation on context menu. Right-clicking on a node will cause this context menu to appear:

NODE CONTEXT MENU Double-clicking on a node is the same as selecting Properties on this pop-up menu. The following pop-up menu appears when you right-click on a member:

MEMBER CONTEXT MENU Double-clicking on a member is the same as selecting Properties on this menu.

The Node Properties Dialog Box The dialog box shown below appears when you double-click a node or select Properties after right-clicking a node.

NODE PROPERTIES DIALOG BOX The OK button in this dialog box is disabled. You may use the dialog box to check properties but you will not be able to change them.

The Member Properties Dialog Box

The dialog box shown below appears when you double-click a member or select Properties after rightclicking a member.

MEMBER PROPERTIES DIALOG BOX The OK button in this dialog box is disabled. You may use the dialog box to check properties but you will not be able to change them.

Properties Dialog Boxes with Multiple Selection You may select several nodes or members, then right-click and choose Properties on the context menu. The dialog box will display common properties of the selected group of nodes or members. Blank edit boxes indicate that the corresponding value is not the same for all of the multiple selection.

Extrusion There is a check box for "Extrude nodes" in each of the Linear Copy, Polar Copy, and Reflect dialog boxes. When you perform a copy operation you may "extrude" each copied node into a series of members in other words, there will be a string of new members lying on the path traced out by each node involved in the copy operation. The member x axis is aligned with the direction of extrusion.

Interrupting Commands The diagram below shows the View toolbar, normally docked at the top of the MSTower window.

VIEW TOOLBAR

Most commands may be interrupted in order to change the view by clicking on one of these buttons. This is helpful in many situations, for example, when drawing a member, and the view required for displaying the "B" node is different from that in which the "A" node is visible. You may interrupt graphical commands to rotate the view, zoom in to a congested area of the model, or pan the view, as required. You may also interrupt commands by clicking buttons on the Display toolbar, shown below.

DRAW TOOLBAR

The Stretch Command The Structure > Move > Stretch command applies a linear transformation to the coordinates of selected nodes. The prompts in the status bar guide you through the necessary steps in this command: Select nodes Select node as fixed point Select node as start point of stretch vector Select node as end point of stretch vector An example is illustrated below, where the top chord nodes of a truss are "stretched" to introduce a uniform slope from one end to the other.

Firstly, a member is added to represent the stretch vector. All the nodes to be transformed are highlighted. Node 2 is selected as the fixed node.

Nodes 12 and 13 are selected to define the stretch vector. The diagram below shows the truss on completion of the command.

If you inadvertently click on the wrong node when selecting the fixed node or the start of the stretch vector, you can abort the command by selecting the start of the stretch vector as the end point also. The Stretch command could be used to input tower cross-arms as a parallel chord truss, which is later

tapered, as in the example above.

The Limit Command

VIEW > LIMIT > WINDOW The commands on the View > Limit menu allow you to restrict activity to a selected part of the structure. The rest of the structure may be greyed out or hidden from view. This has the advantage that the view you are working on is uncluttered by irrelevant detail and the rest of the structure is inaccessible while Limit is in effect. The Limit > Window command was used to select one segment of the tower in the diagram below. To hide the rest of the structure right-click and uncheck Show Outside Limits.

LIMIT > WINDOW When the Limit command is in effect, clicking this button , (equivalent to the View > Zoom > Extents/Limits command) will zoom the view so that the full structure and the limited part alternately fill the screen.

The Limit > Boundary command Clicking the Full View button

may used to select a part of the tower using a selection polygon. reverses the effect of the Limit command.

General While MsTower has an extensive set of standard panels, there will be times when some variant will be required to model a particular panel. MsTower allows you to create your own panels user defined panels, or UDPs, for just this purpose. Unlike standard panels, which are scaled to the dimensions specified in the tower data file, UDPs once created are of fixed size. Although data for the UDP is contained in a text file which may be edited, the most expeditious way of creating a UDP is to start by building a tower with standard panels that are as close to the final configuration as possible, and then to extract and graphically edit a panel as required. MsTower has facilities (see General) that allow UDPs to be created and manipulated using a CAD-like interface. For most UDPs you will never need to edit the text file.

The UDP File Data for user defined panels must be included in one or more separate UDP files. The file names are specified in the COMPONENT block of the tower data file. The data may represent a full face, a half face, a quarter of a section of the tower, a pair of adjacent faces, or a complete three dimensional section of the tower, depending on which is most convenient for describing the panel. MsTower will generate the complete panel. The data for the user defined panel is: UDP udp HT ht TW tw BW bw {PLANE | HALF | QUART | ADJA | 3DIM} NODE n x y z ... MEMB m ia ib ic mp mm pina pinb code ... END

where: UDP udp HT ht

TW tw

BW bw

Keyword. Name of user defined panel as used in the COMPONENT block of the tower data file.. Keyword. Height of panel. This should be the height of the panel between its points of attachment to the panels above and below. It is not necessarily the maximum overall height of the panel. Keyword. Top width of the panel; i.e. the width of the panel at the level at which it attaches to the panel above. If not given, the width of the tower at this level will be interpolated. Keyword. Base width of the panel; i.e. the width of the panel at the level at which it attaches to the panel below. If not given, the width of the tower

PLANE

HALF

QUART

ADJA

3DIM NODE n x y z

MEMB m ia ib ic

mp mm pina

pinb code

at this level will be interpolated. Keyword indicating that the data applies to a plane face that is to be used to generate a full face panel. The panel lies in the Y-Z plane with all X coordinates zero. Keyword indicating that the data applies to half a plane face lying in the YZ plane with all X coordinates zero. Keyword indicating that the data applies to two adjacent half panels disposed about the leg in the positive X and negative Y quadrant. Keyword indicating that the data applies to two adjacent faces. This is used for panels where the adjacent faces differ. The positive X and positive Y faces should be defined. Keyword indicating that the data applies to a full three-dimensional section of the tower. Keyword. Node number. X coordinate of node. Y coordinate of node. Z coordinate of node. The points of attachment to the panel immediately below should have Z coordinates of zero. Keyword. Member number. Node number of the "A" end of the member. Node number of the "B" end of the member. Reference or "C" node. Face members, such as legs and braces, should have a node in the plane of the face as their reference node. This is of particular importance for legs that have staggered face bracing and for face braces such as unequal angles that must have a particular orientation. Section property number. The section must be defined in the SECTIONS block of the TD file. Material number, usually 1. Pin code for "A" end of member, a six character string of 0s and 1s. From the left, 1s represent force releases for Fx, Fy, Fz, Mx, My, and Mz, respectively. Pin code for "B" end of member. Member type code: LEG Leg member. BRC Brace member, other than XBR or KBR. XBR X brace, symmetrically braced. KBR K brace, symmetrically braced. HOR Horizontal member. HBR Hip brace. PBR Plan brace. This code applies only to the internal members of plan bracing. Any plan

brace member in the face of the tower must be classified as HOR. RED Redundant member. CRM Cross-arm main member TBR Tension only bracing. The dimensions of the UDP are taken from its coordinates. The height and panel widths are used to locate the UDP in the tower and to allow any standard panels that are above or below the UDP to be correctly scaled. Unlike standard panels, user defined panels cannot be scaled.

UDPs

UDPs

Making A UDP Using Graphics Input The simplest way to make a UDP is to generate a tower using standard panels that are close in configuration to the required panel, and then to use graphical input to extract the panel and make any necessary modifications. MsTower has commands to convert this to a UDP, but the component references must be put into the tower data (TD) file using the editor. To use this module effectively you must use the Structure > Attributes > Material Number command to set the material number for members as follows: LEG

100

BRC

200

XBR

300

KBR

400

HOR

500

HBR

600

HST

700

PBR

800

RED

900

CRM

1100

TBR

1200

Leg members. Bracing, other than X braces or K braces. X braces. K braces. Horizontals (redundants). Hip braces. Hip stays. Plan braces. Redundant or secondary members. Main members of cross-arms. Tension-only bracing (requires non-linear analysis).

During the conversion to a UDP the material number of a member is used to determine its class. The material number in the UDP will be set to the units value of the material number (or 1 if this is zero). The name of the UDP and its type (PLANE, HALF etc.) will be requested. The HT, TW, and BW will be filled in but should be checked, particularly in the case of cross-arms. If the UDP contains leg members, the HT, TW, and BW values will be determined by examining the coordinates of those nodes that are on legs. The Z coordinates of all nodes will be adjusted so that the lowest "leg node" has a Z coordinate of zero. If the UDP does not contain leg members, the HT value will be set to zero and no adjustment will be made to the Z coordinates.

UDP Example Below is a step-by-step procedure for making a UDP: Step 1

Create Tower

Create a tower (using panels similar to those required) using theTower > Build Tower > Make Tower Data File command.

MAKE TOWER DATA FILE COMMAND List all the sections required at the bottom of the tower data file. Display the tower looking along either the X or Y axis and select the Tower > Build Tower > User Defined Panels > Graphical Edit command. This will enable the menu items that allow graphical editing and input. Step 2

Erase Members

Select the Structure > Erase Members command. Delete all the tower except the panel you wish to use as a template. You may drag a selection box to select groups of members or pick individual members. Note that bottom horizontal members in a panel normally should be deleted as they will overlap the horizontal members in the top of the panel below in the final tower. Step 3

Draw New Members and Input Attributes

Select the Structure > Drawing Settings >Middle/End command. Select the Structure > Draw Members command and draw in the members required. Select the Structure > Attributes > Section Number command and assign section numbers to all the members. Select the Structure > Reference Node/Axis command and confirm the orientation of any members

not matching the defaults. Select the Structure > Material Number command and enter the material number corresponding to the member type shown in the table above.

SECTION ORIENTATION COMMAND Step 4

Make UDP

Select the Graphics To UDP File command.

GRAPHICS TO UDP FILE COMMAND If the message box below appears you have not entered valid material numbers to set the member types in the UDP. Return to Step 3 and complete the assignment of material numbers.

MATERIAL NUMBER ERROR Step 5

Complete UDP Details

Complete the entries for the UDP name and UDP type in the dialog box shown below.

UDP DETAILS Step 6

Edit TD File

Select the Tower > Build Tower > Edit Tower Data File command and enter the lines marked below as $ NEW and $ CHANGE.

EDITING THE TD FILE Step 7

Process TD File

After modifying the Job.TD file and saving the modifications, select the Tower > Process Tower Data File command and then check the structure visually.

Modifying An Existing UDP

UDP TO GRAPHICS COMMAND Select the UDP To Graphics command and the dialog box below will be shown. Select the UDP to be edited and proceed as if part way through making a UDP.

SELECTING UDP FOR GRAPHICAL EDITING

Towers With Unequal Length Legs At times, to save earthworks, towers built on sloping sites will have their leg supports at different levels. This can be modelled in MsTower by using a UDP for the lowest panel. However, as the algorithm used in the loading module requires the legs to have the same foundation level, the shorter legs of the UDP must be extended with "dummy" leg members to give the same foundation level as the longest leg. Supports will be required at the true foundation level and also at the base of the dummy extensions. These may be specified within the SUPPORTS block as described previously.

Index

Face Panels

Index

Plan Bracing

Index

Hip Bracing & Cross-Arms

Index

D & V Face Panels

X Face Panels

K Face Panels

M Face Panels

W Face Panels

XMA Face Panel

DM Face Panel

DMH Face Panel

DLM & DRM Face Panels

KXM Face Panel

XDMA Face Panel

Plan Bracing

Hip Bracing

Cross-Arms

General Data describing the tower geometry is entered into a free-format text file called Job.TD, where "Job" is the job name. A rudimentary tower data file may be generated by selecting the Tower > Build Tower > Make Tower Data File command. The dialog box shown below appears for you to enter the basic geometric parameters.

GEOMETRY PARAMETERS DIALOG BOX You may then enter details for each panel in this dialog box.

PANEL DETAILS DIALOG BOX The resulting tower data file is shown below. It must now be customized for the particular tower you are modelling. The file will be displayed in the MsEdit text editor when you select the File > List/Edit File command and then choose "TD". TITL1 Test tower TITL2 UNITS 1 PROFILE FACES 4 WBASE 4.0000 RLBAS 0.0000 PANEL 1 HT 1.000 TW 1.000 FACE X $ LEG ? BR1 ? H1 ? PANEL 2 HT 1.000 TW 1.000 FACE X $ LEG ? BR1 ? H1 ? PANEL 3 HT 1.000 TW 1.000 FACE X $ LEG ? BR1 ? H1 ? PANEL 4 HT 1.000 TW 1.000 FACE X $ LEG ? BR1 ? H1 ? END SECTIONS LIBR P:UK IFACT 0.1

$ 1.00

1 2 3 4 END

EA200X200X16 EA150X150X10 EA100X100X8 EA70X70X6

BOLTDATA $ TODO - bolt data goes here - format of bolt data: $ [ X x Y y Z z NSP nsp LJ lj ] END END

RUDIMENTARY TOWER DATA FILE

The Tower Data (TD) File The tower data file is organized into logical blocks: 1. Title block. 2. Component block. 3. Profile block. 4. Supports block. 5. Guys block. 6. Sections block. 7. Material block. 8. Bolts block. Each block commences with a keyword identifying the block and terminates with the keyword END. The keyword EOF is used to terminate the file. Each data block is described in this chapter. More: Title Block Component Block Profile Block Supports Block Guys Block Sections Block Material Block

Bolt Data Block Guy Library

Title Block TITL1 titl1 TITL2 titl2 UNITS units

where: TITL1 titl1 TITL2 titl2 UNITS units

Keyword. First line of job title. Keyword. Second line of job title. Keyword. Integer value indicating system of units being used 1 or 4. 1 = SI units. 4 = US units.

Component Block Although MsTower provides a comprehensive range of panel types, there may be times when you wish to define additional panel types. This block allows you to reference a file containing panel data to be included in the tower. COMPONENT udp file ... END

where: udp file

Name (1-8 characters) of a user-defined panel. Name of file containing the data for the userdefined panel. The file may contain more than on user defined panel. It is recommended that the UDP file have the same name as the job. It must have the file name extension "UDP".

Profile Block This block provides the data used to generate the node coordinates and member connectivity of the tower. Panels are described in order, from the top of the tower. The block contains descriptions of the face bracing, plan bracing, hip bracing, and cross-arms. Section property numbers may be assigned to the various types of members in each panel; the property number for a member type need not be specified again unless there is a change. Panel widths need to be input only at the bend points; intermediate widths will then be interpolated automatically. PROFILE FACES WBASE RLBAS PANEL BOLT FACE

nface wbase rlbas nn HT hpanl [TW bpanl] [scale] class nbolt [bolt_id] class nbolt [bolt_id]... ftype [SPACE s1 ... ns @ sm ... sn]... [F1 f1 F2 f2]... [NTR ntr] [ND nd] [NPL npl]... [D] [INV] [LEFT]... [LEG leg BR1 br1 BR2 br2 BR3 br3... H1 h1 H2 h2 R1 r1 ... R9 r9]... [LA la] [LB lb] [LC lc] [LD ld] PLAN ptype [PB1 pb1 PB2 pb2 PB3 pb3 ...]... [F1 f1 F2 f2] [locn] HIP htype [NTR ntr] [ND nd] [HP1 hp1] [HP2 hp2] CROSS ctype [X | Y] [SPAN span] | [SL sl | SR sr]... [RL rl] [RR rr] [CR1 cr1 CR2 cr2 ...] PANEL ... END

where: FACES nface WBASE wbase RLBAS rlbas

PANEL nn HT hpanl TW bpanl scale

Keyword. Number of faces in the tower, either 3 or 4. Keyword. Base width of tower; i.e., the base width of the lowest panel. Keyword. RL at tower base with respect to the ground level at the site. The nodes at the bottom of the legs will have this value as their Z coordinate. Keyword. Panel number. Keyword. Panel height. Keyword. Width at top of panel. If not given, this value will be interpolated. Optional keyword pertaining to variable dimensions F1 and F2: FR

F1 and F2 are factors; the actual dimensions are obtained by multiplying a length as shown on the panel diagram. LE

F1 and F2 are lengths.

BOLT class

If omitted, fractional scaling, FR is assumed. Keyword. Member class, one of the following member types: LEG

Leg members. BR BR1..BR3

Bracing in the face. H H1 H2

Horizontal in the face. R R1..R9

Face redundant. PB PB1..PB10

Plan bracing. HP HP1..HP10

Hip bracing. CR CR1..CR10

Cross arm members.

nbolt

bolt_id FACE ftype

SPACE s1..sn

ns @ sm

If a mnemonic without a numeric suffix is used, all members of the class will have the number of bolts specified. The number of bolts in the end connection of the member. You may use as many class/nbolt pairs as are necessary. Optional character string, used to identify the bolt in the BOLTDATA table. Keyword. Face bracing pattern type. User defined panels must have their names prefixed with the "@" character; e.g. @XYZ refers to a user defined panel XYZ. UDPs may have names with a maximum of 8 characters and must have been referenced in the COMPONENT block. Keyword. List of spacings for XM, DM DLM, DRM ,DMH, KXM and XDM type face bracing. Shorthand way of indicating that a multiple

panel has a number of identical spacings: ns

Number of identical spacings. @

Keyword. sm F1,F2 f1,f2 NTR,ND ntr,nd

NPL npl D LEFT INV

LEG leg BRn brn Hn hn

Rn rn

Value of identical spacing. Keywords. Factors used to locate nodes for some bracing types. Keywords. Number of levels of triangle and diagonal braces, respectively, in some face and hip brace patterns. Keyword. Bracing pattern in part of a portal or cranked K face. Keyword used with XDM bracing. Keyword used with DM bracing. Keyword, used with KB, KBP, KM, KMA, KMG, KMGA, KMGD, KMH, KMHA, KMV, KVH3, and KVS3, indicating that the panel is to be inverted. Keyword. Section property number for leg members. Keyword. Section property number for brace members, type n, where n is a digit from 1 to 3. Keyword. Section property number for horizontal members, type n, where n is a digit from 1 to 2. Keyword. Section property number for redundant or secondary bracing members, type n, where n is a digit from 1 to 9.

All property numbers for a particular member class may be set by using the keyword without a numeric suffix; e.g. BR will set BR1, BR2, and BR3. LA,LB,LC,LD Keywords. la,lb,lc,ld Section property numbers for leg A, B, C, and D, respectively. Leg A is in the positive X-Y quadrant and the other legs are identified in sequence, anti-clockwise from leg A when viewed in plan. The properties of the leg members of the tower may be assigned individually if they are not symmetrical. In any case, a non-zero property must follow the

keyword. Keyword. Plan bracing pattern type. Keyword. Section property number for plan bracing member, type n, where n is a value from 1 to 10. The property numbers for all plan braces will be set to this value if the numeric suffix is omitted from the keyword. Keywords. Factors used to locate nodes for some bracing types. Optional character string indicating the vertical location of plan bracing in the current panel. If omitted, the plan bracing will be placed at the top of the face panel. Must be one of: LEG

PLAN ptype PBn pbn

F1,F2 f1,f2 locn

TOP

Top of the face panel. BTM

Bottom of the face panel. This may be required with certain inverted face panels or type "M" face bracing. XIP

The level of the intersection of cross brace members in the face. MID CROSS ctype X,Y

SPAN span

SL sl

SR sr RL

The mid-height of the face. Keyword. Cross bracing pattern type. Keywords indicating that the cross-arms are to be attached to the X or Y faces of the tower. If not specified the cross-arms will be attached to the Y faces; i.e. they will project to the left and right when viewed from the direction of the X axis. Keyword. Total span of symmetrical cross-arm. If the cross-arm is not symmetrical, separate lefthand and right-hand "half" spans must be specified. Keyword. Left-hand "half" span of the cross-arm. Viewed from the positive X axis direction if attached to the Y faces, or viewed from the positive Y axis direction if attached to the X faces. Keyword. Right-hand "half" span of the cross-arm.

rl RR rr CRn crn

Keyword. Rise of left-hand "half" span of the cross-arm when viewed as described above. Keyword. Rise of right-hand "half" span of the crossarm. Keyword. Section property number for cross-arm member, type n, where n is a value from 1 to 10. The property numbers for all cross-arm members will be set to this value if the numeric suffix is omitted from the keyword.

If a mnemonic without a numeric suffix is used, all members of the class will have the number of bolts specified. Bracing patterns and the location of different member types are shown on the bracing diagrams. Some face panels, such as XTR and KTR, are shown with asymmetrical redundants. In these cases, the arrangement of redundants on the left-hand part of the diagram applies to the X faces of the tower while that on the right-hand side applies to the Y faces. Note: The number of bolts in the ends of members is used in strength checking modules to determine buckling curves or effective slenderness ratios. If the number of bolts is not specified MsTower will assume that all members are single-bolted except for legs, face bracing, and horizontals that are assumed to have two or more bolts. Normally, the bolt specification will be entered in the first panel; it is only necessary to enter changes (if any) in subsequent panels. The bolts themselves will not be checked unless bolt_ids are defined in BOLT statements and bolt information is defined in a BOLTDATA block. Only one set of face, plan, and hip bracing may be specified for any panel. Up to two sets of cross-arms may be specified in a panel to allow panels at the top of power transmission towers where twin earth peaks occur with normal cross-arms. Redundant members are pin-ended. All other members are assumed to be rigidly connected. Any member assigned a property number of zero will be deleted. For example an "X" face panel with H1 = 0 is identical to an "X0" panel. You must ensure that the deletion of members does not result in an unstable structure. When inverting panels, it may be necessary to delete the horizontal member in either the inverted panel or the panel on which it is mounted, if the two horizontals are not sub-divided in identical fashion. "C" nodes, which define member orientation, are allocated in the plane of the face or hip for all members except H1 and H2 type members, where the "C" node is in the direction of the global "Z" axis; i.e. for face members apart from H1 and H2, and hip braces, the member "y" axis lies in the plane of the hip or face. Orientation keywords may be applied to the section definition (see "Sections Block", below) if the section is to be rotated. The example below shows the TD file statements required to generate a pyramidal face panel with two sets of cross-arms.

PANEL 1 FACE CROSS CROSS PANEL 2 FACE PANEL 3 FACE CROSS

HT 1.372 TW 0 X0 LEG 1 H1 0 BR1 0 CT SPAN 6 RISE 7 CR1 10 CR2 12 CT SPAN 8 HT 3.13 TW 1.6 XDM SPACE .788 .787 .788 .787 D LEG 1 H1 2 BR1 2 HT 1.575 XDM SPACE .788 .787 D CT1 SPAN 8.32 CR1 10 CR2 12 CR3 15 CR4 16

PANEL EXAMPLE Plan bracing is located as shown in the diagram below.

LOCATION OF PLAN BRACING

Supports Block This block is optional and may be used to modify the default support conditions of full fixity for all supports except for masts where the legs join at a single pinned support point. SUPPORTS {COORD x y z | LEG abcd} ... {PINNED|FIXED [BUT {releases|springs}]} ... END

where: COORD x y z LEG abcd

Keyword. Coordinates of a node that is to be restrained. Keyword. Leg number in the form of a compact list using

the characters A, B, C, or D. Leg A is in the positive X-Y quadrant. The other legs are identified in sequence, anti-clockwise from leg A when viewed in plan; e.g. AC would indicate that the support conditions apply to legs A and C. PINNED Keyword indicating that the node is pinned; i.e., it is free to rotate but all translational degrees of freedom are restrained. FIXED Keyword indicating that the node is completely fixed; i.e., all degrees of freedom are restrained. BUT Keyword used with FIXED to indicate that some degrees of freedom are to be released or have spring restraints. releases List of degrees of freedom to be released. One or more of: FX FY FZ MX MY MZ springs

List of degrees of freedom that are to be restrained by springs, with the corresponding spring constant. One or more of the following pairs: KFX kfx KFY kfy KFZ kfz KMX kmx KMY kmy KMZ kmz

Guys Block This block pertains to guyed masts only and is used to specify the library containing the properties of guy wires and their arrangement on the mast. GUYS LIB lib XB xb YB yb ZB zb XT xt YT yt Zt zt NO no ANGL angl... TO to KT kt LIB guy_id END

where: LIB lib

XB xb YB yb

Keyword. Name of library containing guy data. It is assumed that the library is located in the data folder unless the name is prefixed with "P:" or "L:". "P:" indicates that the library is in the program folder and "L:" indicates that it is in the library folder. Keyword. Global X coordinate of the lower end of the guy. Keyword. Global Y coordinate of the lower end of the guy.

ZB zb XT xb YT yb ZT zb NO no ANGL angl TO to

KT kt LIB guy_id

Keyword. Global Z coordinate of the lower end of the guy. Keyword. Global X coordinate of the upper end of the guy. Keyword. Global Y coordinate of the upper end of the guy. Keyword. Global Z coordinate of the upper end of the guy. Keyword. Number of guys in this group. Keyword. Angle between successive guys in the group, in degrees. Keyword. Initial guy tension, in kN or kips. The unstrained length of the guy will be adjusted so that when stretched between the undisplaced end nodes, the maximum tension in the guy will equal this value. The still air tension will be less than the initial tension due to the elastic shortening of the shaft of the mast. Keyword. Guy connection efficiency factor. Keyword. Character string of 1 to 16 characters used to identify the guy in the guy library. The properties of the guy required for analysis and design will be taken from the guy library.

The first guy in the group will span between (xb, yb, zb) and (xt, yt, zt), and if no is greater than 1, additional cables will be automatically generated at an angular increment of angl anti-clockwise about the vertical axis of the mast. Guys can be generated only where they are radially symmetrical about the vertical axis of the mast. For example, guys that have their anchor points at different levels because of a sloping site have to be input singly. Usually, guys are input as single members. Guys may also be input as a number of segments to accommodate changes in properties or to allow an insulator to be positioned along its length. In this case, you should input the segments of guy sequentially, commencing at the anchor point and working up to the mast shaft with the coordinates of the lower end of one segment being set equal to those of the upper end of the preceding segment. The segments of guy may be generated as described above.

Sections Block This block specifies the section library and nominates the section to be used for each section property number. SECTIONS LIBR libr

IFACT fact

n sname ...

[X|Y] [CONNECT con] [BH bh] [FY fy]

END

where: LIBR libr

IFACT fact

n sname X Y

CONNECT con

Keyword. Name of library containing section data. It is assumed that the library is located in the data folder unless the name is prefixed with "P:" or "L:". "P:" indicates that the library is in the program folder and "L:" indicates that it is in the library folder. Keyword. Factor by which the section Ixx and Iyy will be multiplied on extraction from the library. When you specify a low value the tower will approach the condition of a space truss with pin-ended members. This is convenient for analysing as a space frame, with sufficient continuity across the joints to avoid mathematical instabilities due to coplanar nodes, but without generating significant bending moments. Section property number. Name of library section. Keywords used to indicate the orientation of the section with respect to the member y axis: X The section XX axis is aligned with the member y axis. Y The section YY axis is aligned with the member y axis. Use of these keywords will allow you to correctly orient asymmetrical sections. For example, if an unequal angle is used in the face of the tower, orientation Y will result in the long leg of the angle being parallel to the face, whereas orientation X will result in the long leg being normal to the face of the tower. Note that the member y axis is not altered by the use of an orientation keyword. See diagram below. Keyword. Single-character mnemonic indicating the connected element of the section: C Concentrically connected (default). L Long leg of angle. S Short leg of angle. F Flange of I, H, or T section. W Web of I, H, or T section. It is important that you specify the connected element for each section. If omitted, MsTower assumes the member is concentrically connected, giving a higher strength than it may actually have.

BH bh

FY fy

Keyword. Effective width of bolt holes, in mm or inches, in the connected element, taking into account any staggering of holes, Keyword. Yield stress of the section. It may be either a numerical value, in N/mm2 (MPa) or Kips/in2, or, a single-character mnemonic indicating the yield strength to be taken from the section library: N Normal yield stress (default). H High yield stress. and H yield strengths correspond to the "y1" and "y2" yield strengths in the MsTower section libraries. In UK libraries, these will normally be based on Grade 43 and Grade 50 steel, respectively. N

The orientation of the section is the cross-section axis (XX or YY) that is coincident with the member y axis (see diagram below).

ORIENTATION OF SECTION Compound Angle Sections The MsTower section library will accept compound angle sections. The compound section types most commonly found in towers and suggested mnemonics are: Type 11: DAL

Double angles, long legs together.

Type 12: DAS

Double angles, short legs together.

Type 16: STA

Double angles, starred or cruciform.

Type 22: QAN

Four angles, cruciform.

These are shown in the diagram below.

COMPOUND ANGLES The data to be entered in the section library source file (Lib.ASC, where "Lib" is the library name) is as follows: $ $ $ S S S S

11 12 16 22

DAL200x100x10 DAS200x100x10 STA100x100x12 QAN100x100x12

Properties of compound section

A Ax Ay J Ix Iy Rx Ry Zx Sx Sy M 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Component dimensions

D B t g sp rv f 200 100 10 10 600 0 0 200 100 10 10 600 0 0 100 100 12 10 500 0 0 100 100 12 10 500 0 0

y1 275 275 275 275

y2 365 365 365 365

The properties, A Ax...M are those of the compound section. Any properties with zero values, as shown above, are computed automatically from the dimensions of the component angles neglecting any toe and root radii. Component dimensions and properties are as follows: D

B

t g sp rv f Y1

Length of the vertical leg of the angle (parallel to the section YY axis) the long leg for unequal angles. Length of the horizontal leg of the angle (parallel to the section XX axis) the short leg for unequal angles. Thickness of the angle. Gap between the component angles. Stitch bolt or packer spacing. 0 = continuously connected. Minimum radius of gyration of the component angle. Reserved, currently zero. Normal yield stress (N).

Y2

High yield stress (H).

Units, which vary from library to library, are specified on the second line of the library source file. Section dimensions and geometric properties are normally in mm or inch units. However, in some UK libraries, derived properties may be in the more customary cm units. When adding to a library, it is recommended that you follow a similar naming convention to that used by a similar section already in the particular library. The section name must not exceed 15 characters in length and the alphabetic mnemonic, which may be anywhere in the name, should not be longer than 4 characters. For example, "DAS200x100x10", "EA4.5x4.5x5/16", "65x65x5.0SHS", and "180UB16.1" are permissible sections names.

Material Block This block is optional. It is used to change the default values of the material used for the tower or the shaft of a mast. MATERIAL E e PR pr DENS dens ALPHA alpha END

where: E

Keyword.

e

Young's modulus (2.05 N/mm2 or 29000 kips/in2). Keyword. Poisson's ratio (0.3). Keyword.

PR pr DENS dens ALPHA alpha

Mass density (7 850 kg/m3 or 490 lb/ft3). Keyword. Coefficient of thermal expansion (12.0E-6 per ° C or 5.9E-6 per °F).

The default material properties are shown above in brackets. Note: Material properties for guys are obtained from the specified guy library.

Bolt Data Block This block specifies bolt diameters, grades, and other data required in checking the capacity of bolted end connections. BOLTDATA

bolt_id grade D d AS as FY fy FU fu FV_EIA fv_eia FV_ASCE fv_asce ... [X x] [Y y] [Zz z] [NSP nsp] [LJ lj] ... END

FV fv ...

where: E bolt_id

D d AS as FY fy

FU fu

FV fv

FV_EIA fv_eia

FV_ASCE fv_asce

X x

Y y

Z z

Keyword. String of 1 to 8 characters used to identify the bolt type in the BOLT statement in the PANEL data above. Keyword. Nominal bolt diameter, in mm or inches. Keyword. Cross-sectional area of the bolt effective in shear, in mm2 or in2. Keyword. Yield stress of bolt, in N/mm2 (MPa) or kips/in2. Keyword. Ultimate tensile stress of bolt, in N/mm2 (MPa) or kips/in2. Keyword. Shear strength of bolt, in N/mm2 (MPa) or kips/in2, used when checking bolts to AS 3995; capacities to this code are strength limit state. Keyword. Shear strength of bolt, in N/mm2 (MPa) or kips/in2, used when checking the capacity of bolted joints to EIA-222-F; capacities to this code are based on working stress. Keyword. Shear strength of bolt, in N/mm2 (MPa) or kips/in2, used when checking the capacity of bolted joints to ASCE 10-90; capacities to this code are strength limit state. Keyword. Distance between end of the member and first bolt parallel to the axis of the member, in mm or in. If omitted, the member checking program assumes that code requirements are met. Keyword. Distance between line of bolts and edge of member at right angles to the axis of the member, in mm or in. If omitted, the member checking program assumes that code requirements are met. Keyword. Spacing between bolts parallel to the axis of the member, in mm or in. If omitted, the member

NSP nsp

LJ lj

checking program assumes that code requirements are met.. Keyword. Number of shear planes. This value needs to be specified only if the number of shear planes in the bolted joint differs from the default values used in the member checking modules. Bolts are assumed to have a single shear plane for all sections except compound sections, DAL, DAS, CBB, and QAN, where the bolts are in double shear. Keyword. Length of the line of bolts in the joint, in mm or in. This value is required only for codes that reduce the strength of long joints. If omitted, the strength will not be reduced.

Bolted joint capacities can be checked only in conjunction with a member check. This has been implemented for all codes other than BS449. A bolt data file called "Bolts" is included in the program folder. You may copy its contents to TD files using Copy and Paste commands in MsEdit.

Guy Library The guy library is a text file containing data giving the dimensions and structural characteristics of wire ropes used as guys. The library may be modified if required. The structure of the guy library file is: GUYS guy-id ... END

d

m

ac

e

alpha

fu

ntype

where: GUYS guy-id d m

Keyword. String of 1 to 16 characters used to identify the guy ropes. Diameter of guy rope, mm. Mass per unit length, kg/m.

ac

Effective cross-sectional area, mm2.

e

Modulus of elasticity, N/mm2. Coefficient of thermal expansion, per °C.

alpha fu ntype

Ultimate tensile stress, N/mm2. Guy type, based on Table 4.1 of BS 8100:Part 4: 1. T4.1(b) Circular sections and smooth wire.

2. T4.1(c) Fine stranded cable. 3. T4.1(d) Thick stranded cable. Note: The guy library uses metric units.

Data Files The tower is described in data files by the minimum number of key dimensions and a description of the types of panel in the tower. Panel types are described by mnemonics of one to four characters. Panels may be selected from a set of built-in face, plan, hip, and cross-arm patterns or may be defined by the user. The following data files are used: Job.TD The tower data file. Job.UDP An optional file containing the description of non-standard or user-defined panels. Job.TWR The tower loading file. It may be convenient to copy the data files from an existing MsTower job and edit these, rather than creating them from the beginning. This may be done by opening the existing job and selecting the File > Save Copy As command to create the new job. The data files are text files, usually created and edited with the built-in text editor, MsEdit. Data is set out in blocks identified by keywords. Blank lines may be used as required to improve the readability of the file. The "$" character may be used to introduce comments; the "$" character and all text following on that line are ignored as input data. Individual items of data may be separated by one or more blank spaces. Each line of data must be no longer than 80 characters. The following conventions are used to describe the input data: Square brackets are used to indicate optional data items. A and B may be omitted in this example: ...[ A ] [ B ]...

Braces are used to indicate where a choice must be made from a list of items. Items may be shown vertically, or horizontally when separated by vertical bars. For example: ...{ item 1 }... { item 2 } { item 3 }

or ...{ item 1 | item 2 | item3 }...

One of the items must be chosen. An ellipsis indicates that the data description in this manual is continued on the next line. Unless otherwise noted, the data in the file must be on one line. The "&" character at the end of a line indicates that the data continues on the next line. Note: Parentheses, braces, and ellipses do not appear in the tower data files. More: Units

Axes Sections Member Checking

Units MsTower accepts two sets of units: Metric using meters, kilonewtons, tonnes, and degrees Celsius, with some data items being input and/or reported in the more customary units of mm and kg. US using feet, kips, kip.sec2/ft, and degrees Fahrenheit, with some data items being input and/or reported in the more customary units of inches and pounds. Entries in the ancillary and guy libraries are required in metric units.

Axes The vertical axis of the tower is parallel to the global Z axis. The X and Y axis of the tower lie in the horizontal plane and do not need to be aligned with the geographic north. The X axis is always normal (in plan) to one face of the tower.

Sections All sections in the tower must be described in an MsTower section library file. Dimensions and properties are automatically extracted to compute surface and projected areas when calculating ice and wind loads and for determining member capacities.

Member Checking You must ensure that wind velocities and other factors used to compute loads are consistent with the code method chosen to check member strengths.

BS 8100:Part 3, AS 3995, and ASCE10-90 are limit states codes, whereas BS449 and EIA/TIA-222-F use permissible stresses.

Errors After assembly of the tower, MsTower checks for the following conditions: Overlaid Members And Unconnected Nodes These occur when a node is coincident with a member but not connected to it. When this occurs it is usually at the junction between panels and happens either because a horizontal has not been deleted or because of an incompatibility between panels. For example if a PL1 plan brace is used with an X face brace the PB1 member will overlay the H1 member. The duplicated member will not be detected by the assembly process because of the mid-side node in PB1. A list of such members will be displayed. Floating Members These are members that are not connected to the structure. If not removed they will result in errors during analysis. They can result if members are deleted; for example if PL1 plan bracing is used with XO face bracing and the PB1 member is deleted, the internal plan bracing members will not be connected to the tower. A list of such members will be displayed. You may readily locate overlaid and floating members using MsTower screen plots. Select the Show > Members command and then enter the list of offending members. The full tower will now be displayed with the listed members highlighted. You may zoom to inspect the members more closely and determine the reason for the error. The TD or UDP file should be modified as necessary. Section Checks The tower builder does a number of sensibility checks as the tower is assembled and reports on the following: Section usage

whether the section is used as a leg, brace, or other type of member.

Whether the connection code is appropriate to the section type. Whether a bolt-hole width has been specified for bolted members. There are also preliminary range checks on the magnitude. You may inspect the above reports by clicking the Build tab on the output window.

Layout The diagram below shows the layout of the MsTower screen. Commands may be initiated from the main menu, any toolbar, or a context (pop-up) menu. The main menu comprises a menu bar, each item of which gives access to a drop-down menu. Some items on drop-down menus lead to sub-menus. Each toolbar button usually corresponds to a command accessible from the main menu. Context menus, which appear when you click the right mouse button, contain a selection of commands from the main menu. This chapter lists all the commands available on the main menu and all toolbars.

LAYOUT OF MSTOWER WINDOW

File Menu Commands

FILE MENU

The File menu offers the following commands: Command New Open Close Save

Action Creates a new job. Opens an existing job. Closes the current job. Saves the current job using the same file name. Save As Saves the current job to a specified file name and changes the name of the current job accordingly. Save Copy Saves a copy of the current job to a specified As file name. Delete Deletes job files, optionally keeping source files. List/Edit File Opens the selected file with the MsEdit text editor for viewing or editing. Page Setup Change the printing options. Print Displays the selected file on the screen, as it Preview would appear printed. Print File Prints the selected file. Export Writes MsTower data to a file for input to another program. Also used for saving job in the form of a MsTower Archive file. Configure Configuration of program capacity, section library, material library, colors, intermediate file folder, and timed backup interval. Also used for editing of section and material libraries and dynamic response spectra. Recent Job Selects recently used job. Exit Exits MsTower

View Menu Commands

VIEW MENU

The View menu offers the following commands: Command Toolbars Status Bar Redraw Limit

Full Zoom

Pan Viewpoint Copy Print Preview Print View Display Options Ancillary Sort Order Model View

Action Shows or hides the toolbars. Shows or hides the status bar. Redraws the current view. Select a part of the structure by one of several available methods. Unselected parts are shown in light grey or hidden. Redraws the current view so that it fills the window. Change the scale of the view or select a rectangular part of the view to fill the display window. Displace the view by the selected distance. Change the orientation of the structure in the view by selecting a new viewpoint. Copy view to Windows clipboard in EMF format. Displays the view as it would appear printed Print the view. Select options for displaying node numbers, member numbers, etc. Specify whether ancillaries will be sorted by serial number or height. Displays a rendered 3-D interactive view of the tower model.

Tower Menu Commands

TOWER MENU The Tower menu offers the following commands: Command Build Tower

Load Tower

Action Opens the tower data (TD) file for editing and processing. Includes graphical creation of user defined panels. Opens the tower loading (TWR) file

for editing and processing. Analyse Analyses the tower. Gust Factor Applies gust factoring to wind forces in tower members. Build/Load/Analyse Runs all the previous items sequentially.

Member Checking Menu Commands

MEMBER CHECKING MENU The Member Checking menu offers the following commands: Command BS 8100 Part 3 BS 449 AS 3995 ASCE 10-90 EIA-222-F Reactions Ancillary rotations

Action Checks members to the rules of BS 8100 Part 3. Checks member to the rules of BS 449. Checks member to the rules of AS 3995. Checks member to the rules of ASCE 10-90. Checks member to the rules of EIA222-F. Reports tower reactions. Reports ancillary rotations.

Structure Menu Commands

STRUCTURE MENU The Structure menu becomes active only when graphically inputting a UDP. It offers the following commands: Command Draw Members Erase Members Select All Drawing Settings Attributes Move Copy Sub-divide Insert Node Intersect Curve Arc/Helix Renumber

Action Draw members or input node coordinates. Erase selected members. Selects all members, including any that may not be visible. Snap modes for drawing members, grid spacing etc. Input attributes of the structure, such as restraints, section numbers, etc. Move a node, move members, rotate members, stretch nodes. Linear copy, polar copy, reflect members. Sub-divide selected members into a number of equal parts. Insert a new node in a member. Insert new node(s) at intersection of selected members. Sub-divide a member into a number of segments whose ends lie on an arc. Create members with ends lying on arc or helix. Renumber nodes and members (sort or compact).

Analyse Menu Commands

ANALYSE MENU The Analyse menu offers the following commands: Command Check Input Linear Non-Linear Elastic Critical Load Dynamic Response Spectrum

Action Check structure and load data (normally automatic). Perform linear analysis (first-order). Perform non-linear analysis (secondorder). Determine frame buckling load factors and buckling mode shapes. Determine natural frequencies and mode shapes. Add response spectrum and static analysis results.

Results Menu Commands

RESULTS MENU The Results menu offers the following commands: Command Action Select Load Cases Select load cases for display of loads or results. Select Natural Select modes for display of vibration Modes mode shapes. Select Buckling Select modes for display of buckling Modes mode shapes. Undisplaced Display structure in undisplaced Shape position. Member Actions Display bending moment, shear force, axial force, torque, or displaced shape. Natural Modes Display vibration mode shapes. Animate Modes Show each currently displayed mode (natural or buckling) in alternate extreme positions. Press the space bar to show the next mode, Esc to cancel.

Buckling Modes Design Ratios

Display buckling mode shapes. Display results of member design check with colors representing range of design ratios. The legend in the output window shows the range of values represented by each color.

Reports Menu Commands

REPORTS MENU The Reports menu offers the following commands: Command Input/Analysis

Action Create report on structure and current analysis results.

Show Menu Commands

SHOW MENU The Show menu offers the following commands: Command Section

Action Highlight members with specified section number. Material Highlight members with specified material number. Member Type Highlight members of specified type (tension-only etc.).

Nodes

Highlight members connected to specified nodes. Members Highlight specified members. Master Nodes Show master nodes. Slave Nodes Show slave nodes. Node Masses Show all nodes with non-zero added mass. Design Show all defined design members. Members Cancel Cancel current "Show" selection.

Query Menu Commands

QUERY MENU The Query menu offers the following commands: Command Node Data

Action List data for selected node (coordinates, restraint, etc.). List displacements for selected node.

Node Displacements Support Reactions List reactions for selected (support) node. Master Node List slave nodes for selected master node. Slave Node List constraints for selected slave node. Member Data List member data for selected member. Member List displacements for selected Displacements member. Member Forces List member forces for selected member. Node Loads List loads for selected node. Member Loads List loads for selected member. Design Member Highlight design member containing

selected member. Note: Query data is displayed in the output window.

Window Menu Commands

WINDOW MENU The Window menu offers the following commands, which enable you to arrange multiple views in the application window: Command Cascade Tile Horizontally Tile Vertically Output Window Window

Action Arranges windows in an overlapped fashion. Arranges windows side-by-side. Arranges windows above and below. Show or hide the output window. All open windows are listed. Clicking one of these will move the focus to the selected window.

Help Menu Commands

HELP MENU The Help menu offers the following commands: Command MsTower Help

Action Display the Help Topics dialog box.

Topics

What's This? Tip of the Day About MsTower

This has three tabs, Contents, Index, and Find, so you can easily find help topics. Display help for clicked buttons, menus, and windows. Show Tip of the Day. Display details about this copy of MsTower and system resources. Also contains links to Internet.

Main Toolbar Commands

MAIN TOOLBAR The Main toolbar offers the following commands: Open a new job. Open an existing job. MsTower displays the Open dialog box, in which you can locate and open the desired file. This command is for opening an existing job one for which there is already a job.MST file, where "job" is the name of the job as it was saved. Save the job with its current name. Print the view; i.e. print a picture showing the current view of the structure. Use the File > Print command to print a file. Print preview; i.e. display exactly how the graphics will be printed. Use the File > Preview command to preview a file.

View Toolbar Commands

VIEW TOOLBAR The View toolbar offers the following commands: Display front view. Display right view.

Display top view. Display oblique view. Move viewpoint to left. Move viewpoint to right. Move viewpoint up. Move viewpoint down. Zoom to extents/limits of structure. If the View > Limit command is in effect, clicking this button alternately displays the full structure and the limited part of the structure. Zoom in. Zoom out. Zoom to selected window. Pan. Show the output window.

Display Toolbar Commands

DISPLAY TOOLBAR The Display toolbar offers the following commands: Display node symbols. Display of node numbers. Display member numbers. Display section numbers. Display supports. Display pins. Display rendered view of members. Display annotation of loads. Display annotation of member force or displacement diagrams.

Increase scale for plotting loads, member forces, or displaced shape. Decrease scale for plotting loads, member forces, or displaced shape.

Help Toolbar Commands

HELP TOOLBAR The Help toolbar offers the following commands: Context ("What's This?") help. The cursor changes to a pointer with a question mark that may be clicked on any toolbar button to provide a pop-up help window. Help About MsTower. MsTower version and configuration details

includes links to Internet.

Draw Toolbar Commands

DRAW TOOLBAR The Draw toolbar is available during graphical input of UDPs only. It offers the following commands: Draw members. Erase members. Move members. Copy members. Reflect members. Sub-divide members. Rotate members. Display grid points and set Grid snap mode. Set Middle/End snap mode.

Set Intersection snap mode.

Attributes Toolbar Commands

ATTRIBUTES TOOLBAR The Attributes toolbar offers the following commands: Input section numbers. Input member releases. Input member orientation reference node/axis.

Results Toolbar Commands

RESULTS TOOLBAR The Results toolbar offers the following commands: Display undisplaced structure. Select load cases for display. Display applied loads. Display member actions. You must turn on this "switch" before you are able to select member forces for display. Display axial force, Fx. Display shear force, Fy. Display shear force, Fz. Display torque, Mx. Display bending moment, My. Display bending moment, Mz.

Display displaced structure. Display natural vibration modes. Display buckling modes. Display design ratios. Design ratios are displayed graphically with different colors representing distinct ranges of values for the percentage of code capacity. For example, members shown bright red are loaded in excess of 110% of the design code capacity. Display member force envelope. Animate modes (natural or buckling). Each mode is displayed in turn. Press the space bar to move to the next mode or Escape to exit mode animation.

OK/Cancel Toolbar Commands

OK/CANCEL TOOLBAR The OK/Cancel toolbar is an alternative to the context menu for confirming or cancelling selections. Display or hide it with the View > Toolbars command. This toolbar is not displayed initially.

Extra Buttons Toolbar Commands

EXTRA BUTTONS TOOLBAR The Extra Buttons toolbar contains a number of buttons that may be added to other toolbars during customization. It is not displayed initially. The buttons available are: Display back view. Display left view. Display y axis for all members. Polar copy. Intersect members.

Insert node. Redraw (F5).

Selecting Which Toolbars Are Displayed You may easily determine the toolbars that are displayed with the View > Toolbars command. This displays the dialog box shown below. All checked toolbars are displayed.

TOOLBARS DIALOG BOX You may also choose the new flat style for toolbars (the "cool" look) or large buttons (these may be preferable at high screen resolutions). Any toolbar that has been customized may be reset to the original configuration by selecting it and then clicking the Reset button.

Customizing Toolbars As well as being dockable, toolbars in MsTower are customizable in two ways. Firstly, while pressing the Alt key you may drag any button to any position on the same or another toolbar. If you drag a button to a new position not on a toolbar, it will disappear. Secondly, you may click the Customize button in the Toolbars dialog box (View > Toolbars command). This displays the Customize property sheet. Clicking the New button creates a new empty toolbar with any specified name. On the Commands tab you may now select any existing toolbar and drag its buttons onto the new toolbar (or any other toolbar).

CUSTOMIZING TOOLBARS

Installing MsTower The Setup program will install MsTower on your computer. Usually, Setup will begin when you insert the CD. If Setup does not begin automatically you must perform these steps: Click on the Windows Start button and select Run. Browse to the Setup program on the distribution CD. Execute the Setup program. Setup will guide you through the installation process, prompting you for a name for the program folder (the default is C:\Mstower), and then copying the required files to the hard disk. Any required fonts will be installed if they are not already installed.

Hardware Lock Most systems are supplied with a hardware lock that must be plugged into a printer port before you can start MsTower. Additional information on the hardware lock is supplied on a data sheet. An extra installation disk is provided for Windows NT/2000 and network systems. Additional setup procedures are described on the associated data sheet.

Folders The Setup program will establish a number of folders under the specified MsTower folder. If you use the default name the folders as displayed in Windows Explorer will look like this:

MSTOWER FOLDERS Folder Name Mstower .....Data

Comment MsTower folder you can choose this name during installation. "Mstower" is the default. Default data folder you can open MsTower files in other folders if you wish.

.....Drivers

Folder for hardware lock drivers, network lock drivers, and documentation files. This folder is created optionally during installation. For a network installation the Net folder contains additional files. .....Examples Example files useful for testing and learning. .....Program All MsTower program files, library files, and Help files. Library File Folder You may use the File > Configure > General > Library File Folder command to specify a folder for library files anywhere on the computer or in the Network Neighborhood. Files in this folder will be accessed when you refer to a library file with the "L:" prefix. Using the "P:" prefix will cause MsTower to look in the Program folder for library files. Library file references that do not have a prefix cause MsTower to look in the data folder for library files. Temporary File Folder By default, MsTower writes intermediate data to the Windows temporary file folder. This is usually most satisfactory for all types of installation. You may, however, use the File > Configure > General > Temporary File Folder command to specify a different folder anywhere on the computer or in the Network Neighborhood.

Starting MsTower The Setup program creates an MsTower item on the Windows Programs menu (click Start, then Programs). Click on this item to start MsTower . If you have not previously used MsTower you should start with some of the examples supplied with MsTower to familiarize yourself with the operation of the principal menu and toolbar items (see Example 3 Space Truss). To run an example, use the File > Open command and click on the required file in the dialog box. You may open any existing MsTower job with the File > Open command. To start a new job based on an old job, open the old job and save a copy with another name using the File > Save Copy As command. You may now close the old job and open the new copy by selecting its name from the most recently used list on the File menu. Note the following powerful Help features, which make it easier for you to use MsTower: There are tooltips on all toolbar buttons. Move the mouse cursor over the button for a moment and a little pop-up window displays the function of the button. There is a prompt displayed on the left side of the status bar (at the bottom of the MsTower window) whenever the cursor is positioned over a toolbar button or a menu item. Look here for prompts while you are performing input operations. Context-sensitive help is available for all toolbar buttons by clicking the

button. Once you have

clicked this button, move the new cursor to any item and click. Context-sensitive (pop-up) help is available in dialog boxes. Some items in dialog boxes also have tooltips. Use the Help > MsTower Help Topics command to display the Help Topics dialog box. With this, you can browse the table of contents, look through an index, or search all Help topic keywords.

Right-Clicking Away from Any Part of the Tower When you right-click in the main window, away from any node or member, the pop-up menu below appears.

MAIN CONTEXT MENU This provides a very convenient alternative to the main menu for many commands. In effect, you can perform some operations in three different ways. For example, you can display the section number on all members by clicking a button on the Display toolbar, by selecting the View > Display Options command, or by right-clicking and then selecting Section Numbers.

How to Make a Shortcut on the Desktop To make a shortcut to MsTower on your desktop (the background that is visible when no programs are running), right-click on the desktop, select New > Shortcut, and in the Create Shortcut dialog box browse to the Mst.exe file in the MsTower program folder. Set the "Start in" folder to the MsTower data folder. Enter MsTower for the name of the shortcut, and click the Finish button. Note: Many MsTower commands involve the use of the context menu. This is a menu, which is specific to the current operation, that appears when you right-click (press the right mouse button). For example, when

you are drawing a series of members, after clicking on the Draw Members button (the one with the pencil), you click the location of each node, and to finish the operation, you right-click and select Break Line or End Line on the context menu. Also, after you have selected nodes or members for any operation, you right-click and choose OK or Cancel on the context menu.

Launch with Double-Click MsTower job files (Job.MST, where "Job" is the job name) should be identified in Explorer with a distinctive icon. It is convenient to be able to double-click on one of these files in Explorer to start MsTower with the job. To do this, the MST file type must be associated with MsTower. The association between MsTower and the MST file type may be established when MsTower is installed. You may also establish the association with the procedure set out below. Here are the steps necessary to make MsTower launch with a double-click: In Explorer select the View > Folder Options or View > Options command. Select the File Types tab. In the list box search for the MsTower job file type, which may be shown as "MST File" or "MsTower Document". If found, select this file type and click the Remove button. Close the dialog box. In Explorer browse to the MsTower data folder and double-click on any MsTower job file (if the file name extension "MST" is not visible you may see it by right-clicking and checking the properties of the file). The Open With dialog box appears. Click on the Other button and browse to Mst.exe in the MsTower program folder. In the Description box type "MsTower Job File" and click OK. In Explorer select the View > Folder Options or View > Options command. Select the File Types tab, then select "MsTower Job File" in the list box and click the Edit button. Click the Change Icon button and then select the second icon. Click OK to close the Edit File Type dialog box. Click OK to close the Folder Options dialog box. Now, check that you have successfully set up your system by browsing to an MsTower job file and doubleclicking.

Configuration

The first time you start MsTower it will run in a partial screen window. Maximize the Window (use the button next to the X button at the top right of the MsTower window) and the system will thereafter start in a full-screen window. Toolbars may be activated or de-activated using the View > Toolbars command and they may also be floated or moved to different locations on the main Window if desired ("docked"). Toolbar buttons may be dragged from one toolbar to another while the Alt key is held down. Chapter 3 contains more information on how you can customize the toolbars. The File > Configure command allows you to set program parameters such as colors, default library files and design codes, and maximum job size. The default settings for maximum job size will be sufficient for the majority of jobs. Increasing limits unnecessarily can result in slightly reduced operating speed.

FILE > CONFIGURE

Steel Section Libraries A source file is supplied with each steel section library. The source file is a text file with the file name extension "ASC" and the corresponding library file has a file name extension of "LIB" (e.g. Asw.asc, Asw.lib). To make a new library, copy an existing source file to a file with a new name and modify it as required. Use the File > Configure > Edit Library command to modify a library (see Editing the Steel Section Library). It is recommended that you do not modify the standard library supplied with MsTower is preferable to copy it to a file with a different name and then modify that. Steel section libraries used with DOS versions of MsTower are compatible with those used by Windows versions (V5.0 and later).

Data from Earlier Versions MsTower V5 is file-compatible with V3 and V4. All data files (TD, TWR, UDP) and section and ancillary

it

libraries from V3 and V4 are compatible with MsTower V5.

Technical Support MsTower technical support is available by telephone, fax, and e-mail. Use the Help > About MsTower command to display the serial number, the exact version number, and the configuration of your software. This information is required when you ask for technical support. In addition, the Help About dialog box contains hot-links directly to the MsTower Home Page on the Internet and to e-mail Support.

HELP ABOUT MSTOWER The MsTower Web site is a useful source of additional information and provides a facility that allows licensed users to download updates to the software.