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Australian Steel Detailers' Handbook 200UB25.4 X 929i Q/A

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AUSTRALIAN INSTITUTE OF STEEL CONSTRUCTION A.C.N. 000 973 839

AUSTRALIAN INSTITUTE OF STEEL CONSTRUCTION A.C.N. 000 973 839

AUSTRALIAN STEEL DETAILERS' HANDBOOK

Published by: AUSTRALIAN INSTITUTE OF STEEL CONSTRUCTION

Enquiries should be addressed to the publisher: Business address - Level 13, 99 Mount Street, North Sydney, NSW, 2060, Australia. Postal address - P.O. Box 6366, North Sydney, NSW, 2059, Australia. E-mail address - [email protected] Website - www.aisc.com.au

© Copyright 1999 Australian Institute of Steel Construction All rights reserved. This book or any part thereof must not be reproduced in any form without the written permission of the Australian Institute of Steel Construction.

i \

First edition 1999

National Library of Australia Cataloguing-in-Publication entry: Australian steel detailer's handbook. 1st ed. Bibliography. ISBN 0 909945 79 9. 1. Building, Iron and steel - Handbooks, manuals, etc. 2. Building, Iron and steel - Details - Handbooks, manuals, etc. 3. Steel, structural - Handbooks, manuals, etc. I. Australian Institute of Steel Construction. 624.1821

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Production & Artwork by Redmark Pty Ltd 6 Kuru Street, North Narrabeen, NSW 2101, Australia DISCLAIMER Every effort has been made and all reasonable care taken to ensure the accuracy of the material contained in this Publication. However, to the extent permitted by law, the Authors, Editors and Publishers of this Publication: (a) will not be held liable or responsible in any way; and

(b) expressly disclaim any liability or responsibility, for any loss, damage, costs and expenses incurred in connection with this Publication by any person, whether that person is the purchaser of this Publication or not. Without limitation, this includes loss, damage, costs and expenses incurred if any person wholly or partially relies on any part of this Publication, and loss, dam~ge, costs and expenses incurred as result of the negligence of the Authors, Editors or Publishers.

WARNING This Publication should be not used without the services of a competent professional person with expert knowledge in the relevant field, and under no circumstances should this Publication be relied upon to replace any or all of the knowledge and expertise of such a person.

ii

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

I

Australian Steel Detailers' Handbook

Contents PAGE

Foreword ............................................................................. vii Acknowledgements .................................................................... vii Preface ............................................................................. viii Notation ............................................................................. ix Abbreviations .......................................................................... ix

1.

2.

3.

4.

INTRODUCTION .................................................................. 1-1 1.1

Drafting as a means of communication ............................................. 1-1

1.2

Detail drawings ................................................................ 1-1

1.3

Project organisation ............................................................ 1-2

1.4

Function of the steel detailer ..................................................... 1-4

1.5

Other fields of activity ........................................................... 1-4

STRUCTURAL STEEL . ............................................................ 2-1 2.1

Plain material ...... : .......................................................... 2-1

2.2

Compound sections ............................................................ 2-5

2.3

Characteristics ................................................................ 2-5

2.4

Specifications ................................................................. 2-5

2.5

Physical properties ............................................................. 2-6

2.6

Steel production ............................................................... 2-7

2.7

Tolerances ................................................................... 2-7

DRAFTING EQUIPMENT AND DRAFTING PRACTICES ............................ 3-1 3.1

Manual drafting equipment ..................................................... ~-1 .

3.2

Computer ~ided drafting ..................................................... : ..-s-2-

3 .3

Drafting practices . . . ........................................................... 3-6

3 .4

General procedure . . .......................................................... 3-22

3.5

Approval of completed drawings ................................................. 3-29

ARRANGEMENT AND DETAIL DRAWINGS ........................................ 4-1 4.1

Composition of a typical structure ................................................. 4-1

4.2

Design loading ................................................................ 4-2

4.3

Information provided by the designers ............................................. 4-2

4.4

Drawing sheets ................................................................ 4-5

4.5

Holding down bolt layouts ....................................................... 4-5

4.6

General arrangement drawings ................................................... 4-5

4.7

Detail drawings ............................................................... 4-12

4.8

Components of steel-framed industrial buildings .................................... 4-14

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

iii

5.

6.

7.

8.

iv

FUNDAMENTALS OF STRUCTURAL ENGINEERING . .............................. 5-1 5 .1

Reactions . . . . . . . . . . . . . . . ..................................................... 5-1

5 .2

Shear . . . . . . . . . . . . . . . . . . ..................................................... 5-3

5.3

Bending moment .............................................................. 5-3

BOLTING ......................................................................... 6-1 6.1

Introduction .......................................... ' .-...................... 6-1

6.2

Bolt types .................................................................... 6-1

6.3

Bolting categories ............................................................. 6-2

6.4

Design of bolts ................................................................ 6-3

6.5

Bolt length selection ............................................................ 6-3

6.6

Detailing ..................................................................... 6-7

6. 7

Installation of bolts ............................................................. 6-9

6.8

Preparation of bolt lists ........................................................ 6-12

WELDING ......................................................................... 7-1 7.1

Introduction .................................................................. 7-1

7.2

Joint and weld types . . . . . . ............... ~ . . ................................... 7-1

7.3

Edge preparation .............................................................. 7-4

7.4

Reinforcement and backing ...................................................... 7-5

7.5

Incomplete penetration butt welds................................................. 7-5

7.6

Welding positions .............................................................. 7-6

7.7

Practical guidelines ............................................................ 7-7

7.8

Welding symbols .............................................................. 7-7

7 .9

Clearance for welding ......................................................... 7-13

7 .10

Method of giving field instructions ................................................ 7'.c 16

STANDARDISED STRUCTURAL CONNECTIONS .................................. 8-1 8.1

Introduction ...... ~ ............................................................ 8-1 .

8.2

Angle seat connection .......................................................... 8-2

8.3

Bearing pad connection ......................................................... 8-3

8.4

Flexible end plate .............................................................. 8-4

8.5

Angle cleat connection .......................................................... 8-6

8.6

Web side plate ................................................................ 8-6

8.7

Welded beam-to-column moment connection ....................................... 8-9

8.8

Bolted beam-to-column moment end plate connection ............................... 8-10

8.9

Splices ..................................................................... 8-11

8.10

Purlin and girt cleats ........................................................... 8-15

8.11

Column base plates ........................................................... 8-16

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

__,

9.

BEAMS AND GIRDERS .. .......................................................... 9-1 9.1

Introduction .................................................................. 9-1

9.2

Shop drawings ................................................................ 9-1

9.3

Beam detailing practice ......................................................... 9-1

9.4

Alternate systems of longitudinal dimensioning ....................................... 9-5

9.5

Example of detailing a typical beam ............................................... 9-6

9.6

Example of detailing similar beams ................................................ 9-8

9. 7

Detailing welded plate girders .................................................... 9-8

9.8

Erection clearances ........................................................... 9-10

9.9

Fittings ..................................................................... 9-11

10. COLUMNS .. ..................................................................... 10-1 10.1

Introduction ................................................................. 10-1

10.2

Column bases ............................................................... 10-2

10.3

Splices ............................... , ..................................... 10-3

10.4

Column schedules ............................................................ 10-3

10.5

Column detailing practice ...................................................... 10-3

10.6

Example of detailing a multi-storey column ......................................... 10-7

1O.7

Example of detailing a "portal frame column ......................................... 10-7

10.8

Ancillary details ............................................................. 10-11

11. TRUSSES .................................................. : .................... . 11-1

.1 .

...

11.1

Introduction ................................................................. 11-1

11.2

Types of trusses .............................................................. 11-1

11.3

Chord and web sections ....................................................... 11-2

11.4

Layout and scales ............................................................ 11-2

11.5

Symmetry and rotation ......................................................... 11-2

11.6

Dimensioning ................................................................ 1j-2

11.7

Node poin.t~ - bolted construction ................................................ 1-1-3-

11.8

Node points - welded construction ............................................... 11-4

11.9

Example of detailing a welded truss .............................................. 11-7

11.10

Cambers . . . . . . . . . . .......................................................... 11-8

12. BRACING ........................................................................ 12-1 12.1

Introduction ................................................................. 12-1

12.2

Bracing connections .......................................................... 12-1

12.3

Setting out and detailing of bracing ............................................... 12-1

12.4

Example of detailing of floor bracing .............................................. 12-1

12.5

Additional considerations ....................................................... 12-4

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

v

13. PURLINS, GIRTS AND EAVES STRUTS ........................................... 13-1 13.1

Introduction ................................................................. 13-1

13.2

Purlins ...................................................................... 13-1

13.3

Bridging systems ............................................................. 13-1

13.4

Detailing purlins and bridging .................................................... 13-3

13.5

Girts ....................................................................... 13-3

13.6

Eaves struts ................................................................. 13-3

14. PORTAL FRAMES ................................................................ 14-1 14.1

Introduction ................................................................. 14-1

14.2

Design of portal frames ........................................................ 14-1

14.3

Design details ................................................................ 14-3

14.4

Eaves and apex set-out ........................................................ 14-3

14.5

Shop drawing ................................................................ 14-5

14.6

Pre-set of portal frames ........................................................ 14-7

15') STAIRWAYS ...................................................................... 15-1 15.1

Introduction ................................................................. 15-1

15.2

Design of stairways ........................................................... 15-1

15.3

Detailing .................................................................... 15-4

16. DETAILING FOR ECONOMY ...................................................... 16-1 16.1

Introduction ................................................................. 16-1

16.2

Communication .............................................................. 16-1

16.3

Economy in the use of material .................................................. 16-1

16.4

Rationalisation of member sizes and repetition of details .............................. 16-2

16.5

Standardised details ........................................................... 16-2

16.6

Accuracy in detailing .......................................................... 16-2

16.7

Fabrication ....••........... , ................................................ 16-3

16.8

Bolting ..................................................................... 16-4

16.9

Welding ..................................................................... 16-6

16.1 O

Transportation ............................................................... 16-6

16.11

Erection .................................................................... 16-7

17. REFERENCES .................................................................... 17-1 17.1

Australian standards ........................................................... 17-1

17.2

Other references. . . . . . . . . ..................................................... 17-2

17.3

Further information ............................................................ 17-2

APPENDIX A Fabrication of structural steelwork APPENDIX B Sample project drawings

vi

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

( . ..~:

FOREWORD The Australian Institute of Steel Construction (AISC) is a national non-profit organisation dedicated to increasing knowledge and understanding of the use of structural steel in our society. Through planned research and development programmes, industry seminars and publishing technical work the Institute provides leading edge technology and best practice engineering solutions contributing to the growth of structural steel in Australia. Steel construction industry participants who are responsible for the design, fabrication and erection of steel structures are readily able to access the resources cif the Institute. The fabrication and erection of a steel-framed structure requires the co-ordination of trained engineers, architects and technicians. In the structural steel detailer's office, the original concepts of a structure's framework (as shown on the architect's and engineer's design drawings) are interpreted and translated into detail drawings. These drawings, through sketches, lines, dimensions and notes give complete instructions for cutting, punching, drilling and then assembling the various structural members with bolts and/or welds. Through the shop drawing, the steel detailer must convey in technical language all information required for the workshop to fabricate many different types of structural members. To prepare these drawings, a steel detailer must have knowledge of the latest engineering specifications and be familiar with the specialised techniques of workshop fabrication and field erection. \

The purpose of this Ha11dbook is to provide sufficient information for a trainee structural steel detailer (who is involved in a specialist area of structural drafting) to learn the fundamentals of how to detail most members and ,, connections in a simple steel-framed building. The text includes a general section on computer aided drafting (CAD). The reader is assumed not to be an Engineer and some engineering fundamentals are included to help in understanding the procedure. As trainees gain experience, and are trained by studying this book and other AISC publications, they will acquire the knowledge necessary to become competent steel detailers. The AISC publishes other literature on structural steel which includes standalone publications, journals and software. Reference should be made to these items if further information is required.

ACKNOWLEDGEMENTS AISC gratefully acknowledges the contribution and assistance from the following individuals and organisations: • Mr Alan Hawkins (A J Hawkins Ply Ltd) • Mr, Ross Mccaffrey (Steel Plan Australia Ply Ltd) • Mr Ken Morgan (Bayside Drafting (Aust) Ply Ltd) I

··~.

• Mr Terry Phelan (Alfasi Constructions Ply Ltd) • Mr Virice"'Rehbein (BDS Steel Detailers Ply Ltd) • AISC Staff

and those who gave constructive comment on the Handbook's contents. The Handbook is substantially based on the Southern African Institute of Steel Construction (SAISC) publication "Southern African Structural Steelwork Detailing Manual" and some parts of the American Institute of Steel Construction (AISC(USA)) publication "Detailing for Steel Construction". AISC also acknowledges the SAISC and the AISC(USA) for the use of their respective material.

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

vii

PREFACE The Handbook covers the process of structural steelwork detailing, commencing with the fundamentals of drawing, continuing with drafting practice and conventions, the types and behaviour of bolts and welds, the conventional methods of detailing components, and concluding with tips on achieving economy of construction. The Handbook should serve both as a fundamental guide for trainee steel detailers and as a useful point of reference for more experienced personnel. The types of structures covered are those representing the bulk of the typical fabricator's work tasks, i.e. commercial and industrial buildings, portal frames, platforms and towers. More specialised structures, such as bridges, tanks, bunkers, etc are not included. The Handbook is directed mainly at the steel detailer employed by a typical steel detailing firm or steel fabricator to prepare the working drawings that are required by the workshop for fabrication of the steelwork. However, the topics dealt with in the Handbook will also be of interest to draftspersons and designers in associated areas of activity, especially those in architects' and consulting engineers' offices and it is hoped that its contents will be useful in widening the understanding of steelwork drafting requirements. One aim of the Handbook is to instill into steel detailers a sense of importance of their role in the total steel construction activity, and of the need to adopt a responsible attitude towards their work. Due to fabrication shop and project preferences as well as drafting company practices, there may be several options for steel detailing and fabrication methodologies. These options may include welded versus bolted construction, "manual" versus computer numerically controlled {CNC) fabrication, full detailing in the drawing office as against shop set-out of certain details, piece-meal fabrication instead of large shop assembly, and whether manual or computer-aided drafting procedures are used. Consequently, in some instances the Handbook notes alternative procedures or suggested details to convey similar information. Obviously, drafting companies referring to this Handbook should advise their trainees and other interested staff which of the alternatives are preferred in-house. The Handbook is based substantially on the "Southern African Structural Steelwork Detailing Manual" (by the Southern African Institute of Steel Construction, 1994) as it provided some very good material for trainee Australian steel detailers. Hence, the Handbook should be considered to be an evolving publication reliant on industry feedback which, in future editions, will bridge the gap from fundamental guide to industry "code-of-the-practice". Consequently, AISC welcomes comments on improving the Handbook to reach this outcome. So as to make it more useful to trainee steel detailers and other interested parties, the current edition of the Handbook has the following features: • It is published in a ring binder so as to permit the revision of specific sections when they are updated by AISC (this may be initiated by industry feedback) • Based on the fundamental material presented in the body of the Handbook, readers can scrutinise actual steel detail drawings from leading Australian detailing companies for - a sample project with drawings reduced to A4 size format (Appendix 8) - a sample project with drawings presented in A3 format as an attachment within a sleeve to the Handbook • The popular AISC publication "Economical Structural Steelwork" which is referenced by the Handbook and provides important information on the overall aspects of the steel construction industry. It has been assumed that the structures to be detailed have been substantially designed in accordance with AS 4100 and consequently frequent reference is made to this Standard. Other related steel design Standards may include AS/NZS 4600, AS 2327.1 and AS 3990-see Chapter 17. Reference is also made to three AISC publications, namely Standardized Structural Connections (Ref. 1), Design Capacity Tables for Structural Steel, Volume 1: Open Sections (Ref. 2) and Design Capacity Tables for Structural Steel Hollow Sections (Ref. 3). It is essential that every steel detailer should be in possession of Ref.1 and it is highly desireable to have access (possibly through their drawing office library) to Refs. 2 and 3. The emphasis in this Handbook is on detailing and not on the calculation or design of connections. This subject is dealt with in other AISC publications. A list of other steel detailing references is provided in Chapter 17. These references may be useful to those readers wanting more information on the topic.

AISC, 1999.

viii

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

NOTATION a

Thread runout

b

Length of thread

t5

Plain shank length

l

Nominal bolt length

n

Nut height

w

Washer thickness

t

Thickness of ply

t1

The thickness of the ply under the bolt head

tP

Thickness of thinner ply

ABBREVIATIONS '\

The abbreviations listed below are generally used for structural steelwork applications. See also Figure 3.29 for a schedule of basic abbreviations for structural steel detailing and Figure 3.30 for a schedule of typical building construction abbreviations.

4.6/S

· Commercial grade bolts snug tightened

8.8/S

High strength structural bolts snug tightened

8.8/TB

High strength structural bolts fully tensioned bearing-type

8.8/TF

High strength structural bolts fully tensioned friction-type

AISC

Australian Institute of Steel Construction

BOS

Basic Oxygen Steelmaking

BT

Tee Section cut from Universal Beam

CAD

Computer Aided Drafting

CFW

Continuous Fillet Weld

CHS

Circular Hollow Section

CNC

Computer Numeric Controlled

_,,

-~'

"

.GPBW

ASDH/01-1999

Complete Penetration Butt Weld

CT

Tee Section cut from Universal Column

Dia

Diameter

do

ditto

DTI

Design Throat Thickness (of a weld)

E

East

EA

Equal Angle

EAF

Electric Arc Furnace (Steelmaking)

FL

Flat

GP

General Purpose (weld category)

HD

Holding down

IP

Intersection Point

IPBW

Incomplete Penetration Butt Weld

IZS

Inorganic Zinc Silicate

kN

kilonewtons AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ix

'·

lg

long

N

North

No

Number

NTS

Notto Scale

OD

Outside Diameter

PCD

Pitch Circle Diameter

PFC

Parallel Flange Channel

PL

Plate

RFI

Request for information

RHS

Rectangular Hollow Section

RL

Reduced Level

s

South

SECT

Section

SFL

Standard Floor Level

SHS

Square Hollow Section

SOP

Set Out Point

SP

Structural Purpose (weld category)

TFB

Tapered Flange Beam

TFC

Tapered Flange Channel ·

UA

Unequal Angle

UB

Universal Beam

UC

Universal Column

UNO

Unless Noted Otherwise

w

West

WB

Welded Beam

WC

Welded Column

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x

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

-,'.

_,

1. INTRODUCTION 1.1

DRAFTING AS A MEANS OF COMMUNICATION

Drafting is a method of conveying information in pictorial or graphic form. Usually it has to do with the planning or design of an object or structure, whether it be a single set-screw, a multi-storey building or any of an infinite range of items, components, machines or structures. A drawing will not only convey accurately the appearance of the article as built, but will also give the necessary information on how it is to be built. Another means of communicating information is the spoken or written word. However, this process of information transmittal involves very lengthy descriptions and requires the continued presence of the conceiver of the project during the construction process to ensure that the instructions have been understood correctly. It is obvious that even a simple drawing will convey the required information more clearly and accurately and much more concisely than can be done by the spoken or written word and will also reduce the need for supervision.

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''

The steel detailer's function, therefore, is to serve as an intermediary between the conceiver and the executor of the project. Steel detailing is a specialist area of structural drafting. As such, a detailer must be familiar with general structural drafting practice as well as areas specific to steel shop drawings. The detailer needs to have a clear understanding of the designer's intent and must commit this information to paper by graphical means. At the same time the detailer must have a knowledge of the processes involved in the construction or fabrication of the project. The drawing is then both an instruction to the artisan on how the structure is to be built and a permanent record of the designer's intent. It will be evident from this simple illustration that a steel detailer's function is a very important one in the chain of events from the original conception to the final completion of any item or project. It will also be clear that the main requirements in the steel detailer's approach are clarity of presentation, accuracy, speed of work as well as patience and perserverance.

1.2

DETAIL DRAWINGS

Prior to the use of steel as a structural material, the usual practice was to depict, say, a building or a bridge by means of elevations, plans and cross-sections with, where necessary, enlarged details of special parts of the structure that required more detailed description. Thus the elevation of a bridge would be to a scale sufficient to show, by means of suitable annotation, the sizes and shapes of the members making up the girders. Likewise, a plan of the deck would indicate the layout and size of the floor beams. However, the support bearings and any special member end connections would be shown to an enlarged scale, in sufficient detail to enable the ironworker, the carpenter or the blacksmith to construct these components to a reasonable degree of accuracy. However, with the advent of structural steel, prefabrication became essential, and this brought with it the need to supplement the arrangement drawings with detail drawings of all individual members and components. These-are known as shop detail drawings and are usually prepared by a specialist steel detailing company under sub-conff'act to a steel fabricator for.use in jts workshops. The shop detail drawings are based on the layout and arrangement drawings supplied by the owner, or the consulting engineer appointed to carry out the design, and are the means of recording the information required by the workshop personnel to fabricate each and every component of the structure. It is in the preparation of these drawings that structural steel detailers find their role and are able to play a vital part in the sequence of events that comprise the total activity of structural engineering. Examination of any steelwork detail drawing will reveal a stylised presentation, involving the use of standardised abbreviated notation and special symbols. These all form part of the graphical means of information transmittal referred to earlier and enable a large amount of complex technical data to be recorded and conveyed in a simple, concise manner. It is the purpose of this Handbook to introduce the trainee steel detailer to this technical "language" and to present the many techniques and conventions that are used in the structural steelwork industry to convey the necessary information clearly and without ambiguity.

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

1-1

1.3

PROJECT ORGANISATION

At this point it is helpful to consider the overall management and technical organisation that is involved in a construction project and to see where the steel detailer fits. Fig. 1.1 illustrates the stages in the progress of a typical project and indicates the specialised tasks associated with each stage. It also shows the lines of communication between the various parties. The chart is representative of a commercial-type building, where the owner appoints an architect and a consulting engineer and retains financial but not technical control over the planning process. For the sake of simplicity, the chart covers only those activities connected with the medium of construction under consideration, ie structural steelwork. Many other aspects have to be taken into acc_ount in the broad planning of a project, such as cost limitations, location of the project, availability of materials, compliance with building

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SECOND FLOOR PLAN Fig. 3.27: Sample of part Architect's plan showing job set out

3-26

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

Kliplock Hi Ten on 100 'Z' girts

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---------------------- -------------------

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13mm Plasterboard on 76mm stud sections at 600 ctrs

500

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Louvre blade

COLUMN C10 FOURTH FLOOR

Fig. 3.28: Typical Architect's detail

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

3-27

AOE BG BLDG BM BOTorBTM BPL CFW CPBW CTS CIC

t.

DFT DIA DIM EL or ELV FLG FSor F/S GALV GND

As Other End Back Gauge Building Back Mark Bottom Baseplate Continuous Fillet Weld Complete Penetration Butt Weld Centres Cross Centres Centre Line Dry Film Thickness Diameter Dimension(s) Elevation Flange Far Side Galvanise Ground

IP LEV LH NOM NSorN/S OPP 0/A RAD REF RH TOG TOS TP TYP WP U/S TEMP LFH FFL

Intersection Point Level Left Hand Nominal Nearside Opposite Overall Radius Reference Right Hand Top of Concrete Top of Steel Tangent Point Typical Working point Underside Template Locate 1st hole Finish floor level

Fig. 3.29: Schedule of basic abbreviations for structural steel detailing (also_see Abbreviations at beginning of the handbook)

GENERALLY AUG BSN CJ CS EDB EJ FA FCL FD FFL FH FHR FIB FLP FR FW G HCD HD HWU L LP MH RC RS RD S SB SC SD SL

FLOOR AND PAVING FINISHES Perforated corrugated aluminium Basin Construction joint Cleaners sink Electrical Distribution Board Expansion Joint Fabric Awning Finished Ceiling Level Fire Door Finished Floor Level Fire Hydrant Fire Hose Reel Fire Indicator Board Laminated Plastic Fire Rated · Floor Waste Glazing Hollow Core Door Hand Dryer --- ,_ Hot Water Heater Light fitting Louvred Panels Manhole Reinforced Concrete Roller Shutter Relative level Sump Structural Steel Beam Structural Steel Column Solid Core Door Soffitt Lining

CONG CPT FCT FSV FVT PCT POT TF TI TZ

Concrete Carpet Cement Topping Sheet Vinyl Vinyl Tiles Ceramic Tiles Quarry Tiles Timber Floor Terrazzo Tiles Terrazzo

WALL FINISHED CB CFC CR FB FOF FPB TZ WT

Concrete Block Compressed Fibre sheeting Cement Render Face Brickwork Off-form concrete Plasterboard Terrazzo Wall Tiles

CEILING FINISHES AT CAP FOF FPB(F) PB SP

Acoustic Tiles Ceiling Access Panel Off form concrete Plasterboard and Fire-rated Particle board Suspended ceiling system

ROOF AND PLUMBER DP FL GI OF RWH SWP

Storrnwater Downpipe Flashing Gutter Overflow Rainwater Head Storrnwater Pit

Fig. 3.30: Schedule of typical building construction abbreviations 3-28

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

~--

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3.5

APPROVAL OF COMPLETED DETAIL DRAWINGS

After the detail drawings have been completed and checked, prints or reproducibles {often required on large contracts) of the drawings must be submitted for approval before workshop operations begin. This applies to all workshop details and erection plans, since all of these drawings contain some information not specifically shown on the design drawings. This approval is usually given by the design engineer, or by some other individual whose authority to represent the owner has been established in the contract documents. Except for small orders involving relatively little work, the fabricator's drawings are usually submitted for approval in instalments. For example, for multi-storey buildings, plans and details may be submitted for one tier (two floors) at a time. Prompt approval of the drawings is essential to meet work schedules and delivery dates. The fabricator usually includes an allowance in the program for the return of shop drawings. The Project Manager is required to keep a record (on the Drawing Register) showing the dates on which the drawings are submitted for approval and the dates on which they were returned. In conjunction with the Chief Draftsperson, a close watch over this aspect of the work must be maintained. When the approving authority returns prints with notations for corrections the indicated changes must be checked. These changes may affect other work in progress in the drafting office or work already released for fabrication. If found to be in order, the changes should be made promptly and revised drawings issued to the shop. If required, new prints of the corrected drawings are then submitted for approval. Acceptance by the approving authority indicates confirmation of the suitability of the details and adequacy of.the connections. However, the correctness of dimensions on detail drawings and the general fit-up of parts furnished by the fabricator to be assembled in the field, remains the responsibility of the fabricator.· In preparing the detail drawings, should any discrepancies in the design be discovered they must at once be referred to the client, consultant or approving authority. Instructions must be received before proceeding further with the affected part of the work.

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

3-29

[blank]

3-30

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

4. ARRANGEMENT AND DETAIL DRAWINGS 4.1

COMPOSITION OF A TYPICAL STRUCTURE

In Fig. 4.1 the steel framework for a warehouse-type building is shown in elevation, plan and cross section, with the names of the main components given. The drawing shows the structure as it will appear when erected on site, but when detailing the steelwork for shop fabrication it will be necessary for every single component to be separately drawn and fully described. Note that the building is not fully depicted in the views given - e.g. the end walls and the far side of the lean-to are not shown. However, for the purpose of illustrating the names of the components, the figure is adequate.

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1 Main columns 2 End wall columns 3 Lean-to columns 4 Trusses · 5 Lean-to rafters 6 Purlins 7 Bridging

8 Girts 9 Eaves struts 1O Side bracing 11 End wall bracing 12 Roof bracing · :J 13 Door framing 14 End wall rafters

Fig. 4.1: Components of a steel-framed warehouse building Consider the main columns (Item 1) in Fig. 4.1. There are 12 of these items and it is obvious that they will not all be identical because of the different attachments to them, eg girts, bracing, trusses, end wall rafters, lean-to rafters, etc. A careful study will show that there are in fact nine different main columns, seven of which are completely different and two that are opposite hand to others. The columns could therefore be depicted in seven separate details, with the note "One required opposite hand" added to two of them. However, as will be seen later, it is possible to combine certain columns that are almost identical into one detail and thus reduce the number from seven to, say, four. A study of the main trusses (Item 4) will show that of the total of four there will be two types only, with no oppositehand details. Note that the end frames have rafters instead of trusses. Although the trusses to which the rafter bracing is attached appear to be opposite hand, they are in fact identical because one can be swung through 180° in plan to take the place of the other. A structure is thus made up of a number of parts that are in themselves quite separate and diverse. They are manufactured in different parts of the fabrication shop - eg trusses in the welding shop, columns and beams in the punching or drilling bays, etc - yet when they are brought together and connected to each other by bolting or ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

4-1

welding, they form a single unified structure. It is obvious that when each component is being detailed, the steel detailer must have a clear idea of how that component will be connected to the adjacent one. For example, the ends of the trusses must be attached to the tops of the main columns. As this is usually done by bolting, the necessary matching holes must be provided in the truss end cleats and the columns.

4.2

DESIGN LOADING

Loading such as selfweight, imposed loading, wind loading, etc, that the structure must be capable of sustaining is called the nominal loading. It represents the actual loading applied to the structure, and values to be used are specified in the loading codes AS 1170 Parts 1, 2, 3 and 4. The modern method of structural design is called limit-states design, which means that the structure is designed to resist the applied loading under essentially two limiting conditions or states. These are the ultimate and the serviceability limit states.

4.2.1

Ultimate Limit State

This is the state at which the structure, or any part of it, is just at the point of collapse or failure when subjected to a combination of applied loads, these loads being the nominal loads multiplied by appropriate factors. The reason for applying these factors is that it is impossible to estimate accurately the actual intensity of the nominal loads, and so a "margin of safety" must be built in, The combination of loading does not necessarily include all of the loads acting simultaneously at their maximum intensity. For example, when full wind loading is applied other live loading is included at reduced levels, or when full live loading from one source is applied then live loading from a different source is taken at a lower value, ie. a lower factor is used. The factors to be used are called partial load factors, since they vary according to the type of load to which they are applied, whether dead, live, wind, etc. Values are given in the loading code AS 1170 Part 1. Several combinations of loading usually have to be considered by the engineer and the worst combination applicable to any particular member in the structure is used in the design of that member. The factored loading thus derived is called the loading at ultimate limit state, or, more simply, ultimate loading.

4.2.2

Serviceability Limit State

This is the state beyond which the structure or any part of it no longer performs acceptably under the applicable combination of nominal (not ultimate) loading, ie. in its normal use or function. Examples of where this state is exceeded are deflection of beams, side sway of structures under wind or crane surge loading, vibration of structures supporting moving machinery, etc, beyond acceptable limits. The loads applicable are those from nominal loaaing (sometimes reduced by a load factor less than 1.0) and are called the serviceability loads. Values of the load factors for the serviceability limit state are also given in AS.1170 Part 1. It is the responsibility of the ..eogineer_ to ensure that the structure complies with the serviceability limit state. requirements.

4.3

INFORMATION PROVIDED BY THE DESIGNERS

There are four main types of contract documentation methods referred to in Ref. 6. These are: 1. The engineer shows all member and connection details to a level sufficient to allow accurate pricing and shop detail preparation, but insufficient information to enable direct fabrication. 2. The engineer includes fully detailed shop drawings. 3. The engineer shows members and their end reactions only. 4. All engineering information is shown on the architectural drawings. As described in Ref. 6, the first method is the most common method used in Australia. In this case the responsibility for dimensioning of the primary and building dimensions lies with the architect. The engineer shows structural dimensions, eg truss and beam depths, bolt centres, plate dimensions, beam and purlin locations, splice locations, and other specific dimensions which are critical to the structural design. If separate architectural drawings are not provided (examples of such projects would be mining or processing plant projects) the engineer would provide fully dimensioned drawings.

4-2

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

_,

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If reference is made to the project organisation diagrams shown in Figs 1.1 and 1.2 it will be seen that at a certain point in the sequence of events the designers provide design information to the steel fabricator. It is at this stage, ideally, that the steel detailer receives all the data needed to proceed with the task of preparing workshop drawings. The information is usually provided by the designers in the form of general arrangement drawings and a brief specification. The drawings will include a layout of the structure, generally as shown in Fig. 4.1 and typical connection details (see sample drawings in Ref. 6 also). It is essential that the information provided is complete and explicit. The preparation of workshop drawings is an activity lying on the critical path, which means that any delay in the execution of this task will contribute to an extension of the time required to complete the whole project. The contractor will have committed to a fixed hand-over date for the steelwork and any overrun on this date could result in incurring financial penalties for non-compliance. For a steel-framed building, the following design data would be required from the designers (engineers and architects): 1. General arrangement (ie layout) drawings preferably to scale, including elevations, sections and plans, giving a complete representation of the entire building. These drawings should give floor levels, beam spacing, the orientation of the building (by means of a north arrow), location on the site, relationship to other structures (if any) and where appropriate dimensions for the correct location of members, etc.

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Plan views show the locations of column centres and indicate the orientation of column faces. Since the structural plan is generally a small scale line diagram, enlarged sections are sometimes employed to locate off-centre beams and to clarify special framing conditions This is particularly true for perimeter (spandrel) framing, beams around stair wells and ramps, and members to elevator openings. Enlarged parts of the plan, such as those adjacent to corner columns, ma}' _be used to indicate the designer's solution or to alert the detailer to complex situations.

2. The section sizes of all members in the building, eg columns, beams, all truss members, rafters, purlins, girts, bracing, crane beams, stairs, fascia fixings, etc.

3. Drawings of any connections, components or details in the structure that lie outside the scope of generally accepted or standard structural practice.

4. The type of flooring for each suspended floor, eg reinforced concrete slab, composite slab, precast planks and topping, cellular steel deck and concrete, open grating, floor plate, etc.

5. A column base layout, giving the levels of the bases and the holding down bolt details. 6. The grade of steel to be used for the various parts of the building, eg Grade 300 steel for hot-rolled sections.

7. The bolt grades to be used for the shop and site connections. 8. Cambers, if required, for long span plate girders or trusses. 9. The Australian Standard to which the building was designed. 1O. The specifications to which the steelwork is to be fabricated and erected.

-

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In multi-storey buildings withmany columns; a column schedule is of great assistance to the steel detailer, qm19tity_ surveyor and erector. This is a schematic drawing showing the columns only, grouped together row by row,-anq showing section sizes (prebably varying with height), base levels, floor levels and splice locations. Fig. 4.2 represents part of an engineer's floor plan and indicates how beam sizes are shown. Congestion might necessitate that only member marks (e.g. 381, 382, 383 etc.) are shown on the plan (Fig. 4.2(a)) with the members sizes being separately tabulated on the drawing. Connection information would either be included with the member schedule, a connection schedule, or in separate details. If an architect is involved with the project the grid dimensions will be shown on the architect's drawings rather than the engineer's drawings. Unless otherwise indicated by dimensions, members shown on such floor plan drawings are presumed to be: 1 . Placed parallel or at right angles to one another with their webs in a vertical plane. 2. Located at the same particular elevation, and are level from end to end. In either the architect's or engineer's drawings the vertical position of each floor (or beam) is indicated by a figure termed RL (reduced level). The RL, which is typically given in metres, is the distance above an established horizontal plane or datum and may generally be shown on the structure's elevations for a particular floor level -eg (RL 100.000) or (RL 100.075). For a floor with varying levels of top surface of steelwork - ie "top of steel" (TOS) - Rls are sometimes noted on the individual beams as indicated by Fig. 4.2 (b). Alternatively, floor members in this situation may also be noted by "All steel flush top at RL 100.00 except as noted thus (+75)" or 'TOS at RL 100.00 UNO". In this instance, Rls are not shown on those beams which are to be erected with their top flanges at RL 100.00 - eg Fig. 4.2 (a). ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

4-3

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4-4

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

4.4

DRAWING SHEETS

The steel detailer is now in a position to start with the preparation of the drawings to be used for shop fabrication, site erection and general reference. These drawing comprise: a) General arrangement drawings. b) Detail drawings. The size of paper or film will generally be A 1, A3 or B1, depending on the size of the job. Unless done by CAD, most companies have pre-printed drawing sheets containing the following basic details: 1. A borderline around all four sides, about 10 mm to 15 mm in from the edge. 2. A title block giving the company's name, plus open panels for the insertion of the project description, drawing title, job number, drawing number, date, draftsperson's initials, checker's initials and scale of drawing. 3. Additional blocks for the insertion of reference drawing titles and numbers, and descriptions and dates of revisions.

4.5 '\

HOLDING DOWN BOLT LAYOUTS

A task of the detailer is to prepare a holding down (HD) bolt layout. This is a drawing showing the positions of all the column bases (located relative to the column grid lines), with the cross-centres of the HD bolts for each base. The drawing also gives the tO!'kOf-foundation levels, HD bolt projections and grout thicknesses. An example of an HD bolt layout is given in Fig. 4.3. Every column base requires at least two and possibly as many as eight HD bolts to attach it to the concrete foundation. The pupose of the bolts is to position the column base accurately. Bolts also transfer axial (uplift), and shear forces and (possibly) bending moment from the column base into the foundation. Although HD bolts are set in the concrete by the civil contractor, it is usual practice for the bolts to be detailed and supplied by the steelwork contractor. The number, location, diameter and embeddment length of HD bolts should always be decided by the designer. Where enlarged details of column bases are shown, the orientation of the columns in the detail should be the same as in the main plan, to avoid the possibility of the E-W (East-West) and N-S (North-South) bolt centre dimensions being confused. Where practicable the bolt centres in plan should be on a square pattern (ie E-W and N-S dimensions equal), to avoid errors in setting-out, or sufficiently different that correct orientation can be checked by eye on site, before concreting of the base. The projection length of the bolt is usually calculated by the detailer using knowledge of the grout, base plate thicknesses and information from the engimier's drawings. An allowance is also .made for a generous protrusion of_ the bolt thread above the nut. HD bolts are usually made by cutting a standard metric bolt thread on the end:of round bar. The standard diameters of bar are 16 mm, 20 mm, 24 mm and 30 mm.

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The holes in the base plate for the HD bolts should be made considerably larger than the bolt hole diameter, up to 6 mm (as permitted by AS 4100), to allow for inaccuracies in bolt setting. The HD bolt layout should be prepared early on in the drawing sequence, since the setting-out of the bolts at site is always an urgent priority. It is necessary for the detailer to concentrate on the column base details at the earliest opportunity and prepare rough but accurate sketches of all the bases.

4.6

GENERAL ARRANGEMENT DRAWINGS

The general arrangement drawings are similar to those provided by the engineer but include member erection marks. An example of such a drawing is given in Fig. 4.4. The structure depicted is a simple two-storey building and can therefore be shown on a single drawing. Many structures require more than one arrangement drawing, especially when several floor plans are required. An elevation of each side of the building and a plan view of the roof and the first floor are shown. A typical cross-section is essential as it is often the view that contains the most information on the building and it is sometimes drawn to a larger scale, or even depicted on a separate drawing. Much work can be saved if the fabricator can arrange for the engineer to supply transparencies of the engineering drawings or CAD files. The fabricator can then delete any superfluous design information from the drawings and add the detailer's own notation (e.g. erection marks, etc) and own drawing number. The use of CAD makes this ideal situation easily attainable. ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

4-5

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The South and East elevations are shown in Fig. 4.7 and Fig 4.8 respectively. The following should be noted:

1. Erection marks of only the girts, vertical bracing, door framing and rafters are given. All other components, ie columns, beams and roof framing, have their marks given elsewhere.

2. Only special dimensions are given, eg the location of the roller shutter door. All other dimensions are shown elsewhere. -'

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AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

4-11

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4.6.4

Cross-section

The cross-section at Section A-A is shown iri Fig. 4.9. The following should be noted: 1. This view may be drawn to a larger scale in order to show as much typical detail as reasonably possible. 2.

Usually, no erection marks are given.

3.

Full particulars of floor levels, foundation plinth levels and grout thickness are shown.

4. The section sizes of all typical members are shown.

4. 7

Detail Drawings

Detail drawings depict every individual structural member and component in the job and include detailed notes as to their fabrication. This information includes: · 1. The section size and overall lengths of members.

2. The positions and

diamet~r~9f all holes.

3. The positions, types and sizes of all welds. 4.

Dimensions of notches, cut-outs and copes where necessary.

5.

Details of attachments such as cleats, brackets, base plates, stiffeners, bearing plates, etc.

6.

Many other details depending on the type of structure.

Before starting the shop drawings, the steel detailer and fabricator should view the engineer's and architect's design drawings and determine the fabrication methods that will be used for both shop and field connections. Methods change with new developments, but at the present time the following systems are common: (a} Shop welded and field bolted. (b} Shop and field bolted. (c} Shop and field welded. The shop preference for a particular system varies with the available equipment and shop experience. Fabrication plants which have equipment and shop layout adapted to punched or drilled work, perhaps with some machines operated by computer numerical control (CNC), may lean toward the use of bolts. Other shops may be better suited for welding and prefer that all shop connections be welded. Many can handle either type of fabrication, but to balance workloads between shop areas, there may be a preference to select the connection system on a job-to-job basis. 4-12

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

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Generally the connection system is selected by the designer and indicated in the design drawings and the job specifications. However, the designer may be receptive to any proposed changes. A parallel but equally important decision is to determine on which members the detail material will be assembled, ie. the column shafts or the beams. For instance, columns may have considerable detail fittings, splice plates, etc., attached to them. If all this detail material can be assembled and attached to the columns in the shop, the fabricated beams can go to the shop assembly area, then to inspection, painting and shipping areas, while the plain beams (no fittings) go directly to the inspection, painting and shipping areas - an efficient procedure. Special connections and conditions may require some compromise. Any deviations are resolved by management as the drafting proceeds. Since the greater part of the connection material may appear on the columns, preliminary planning is helpful even before detailing is started. In the case of larger buildings this includes an advance preparation of details covering job standards for bracing connections, column splices and other features which repeat throughout the structure. Column and beam gauges are determined, and layouts of bracing connections and standards for framed and seated connections are made. Job standards involving connection material are customarily placed on separate sheets for reference in the drawing office and for use in the template shop. The shop details required for even a relatively small project are seldom produced by one detailer working alone. The tight time schedules of most contracts may require from two to ten detailers working on a single floor level of framing. Early development of complete column details speeds the work and minimizes debates which sometimes arise when several detailers attempt to work up connections to the same column. A well developed set of job standards goes farther in this diniction by providing common standards for both column and beam detailers. Beams, trusses, purlins, girts and girders are drawn in the horizontal position, ie parallel to the lower edge of the sheet. Short columns are drawn in the vertical position, but long columns are placed horizontally, with their bases to the left. Inclined girders, such as sloping conveyor gantries, may be drawn at their true slope or horizontally. The most commonly used scale for detail drawings is 1:10, but in the case of large items such as trusses a smaller scale, say 1 :15 may be used. In certain cases, mixed or composite scales may be used. For example, long members such as purlins, girts, certain bracing members or beams not having much detail along their length may have their length drawn to a smaller scale, but their depth, width and all details {holes, welds, cleats, attachments, etc) drawn to the common scale of, say, 1 :15. However, before this practice is adopted due consideration should be given to the possibility of overcrowding of detail and consequent lack of clarity. In cases of doubt it is best to use the standard scale. As far as possible all the beams and girders on one floor should be shown on one drawing or on consecutively numbered drawings. Rolled beams and welded plate girders should be on separate sheets since they will be fabricated in different parts of the shop. All other similar-type items, whether they be columns, trusses, bracing systems, etc, should like"'(ise be grouped together according to their proximity in the structure and/or ·the construction method, ie bolting or welding. Amongst the other items to be detailed are steel stairways. There is a tendency to regard these as relatively -:; .. unimportant and to leave their detailing until t.he end of the job. In actual fact, they should be given early consideration and accurate layouts shoufd be drawn to ensure that adequate space is available to accommodate them · and the required headroom is available, both overhead and also under landings. Care should be taken to ensure that the supporting floor beams at the foot and head of the stairs are properly located so that the stairs are of the required slope. Detail drawings should be provided with a list of General Notes, stating the grade of steel, the sizes and types of bolts to be used, the diameters of the bolt holes and whether the holes should be drilled or punched, the type of welding electrodes and what painting is required. The above comments on detail drawings are of a general nature and refer to the content of such drawings and the conventions applicable to them. In later chapters, detailed aspects of the graphical representation of various items such as columns, beams, trusses, etc and the particular practices that relate to them will be discussed.

4.8

Components of Steel-Framed Industrial Buildings

Fig. 4.10 is a composite partial representation of an imaginary building, illustrating the many components that go to make up typical steel-framed structures.

4-14

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

(.--..

e; 0

~ ...

l

"'~

~

Cll

9

>

~~ z

!!Im

m

r0

~r-

~

""

:..

~

0 0

3

'C 0 :I CD

~

a "'~ CD

!e.

.!,,

m Ul

iil 3

> z

C"

::11

:c 0

m 0 0

"

!. c

:s::

s· cc

1 2 3 4 5 6 7

Floor beams

Column holding-down bolts Base plates of steel columns Beams, purlins, girts Bearing plates for steel beams

18 Canopy frame 19 Monorail 20 Window framing

Bracing for steel members or frames Brackets attached to steel frame

Columns Conveyor framework 10 Crane rail beams and stops

8

9

11 12 13 14 15

Door frames constituting part of steel frame Floor plates (raised pattern or plain) or grating, connected to steel frame Girders

Grillage beams to column base Headers or trimmers for support of open-web steel joists where headers or trimmers frame into structural steel members

16 Light-gau~e. cold-i?rmed steel decking/cladding . · 17 Lintels built mto brickwork

...

'\"

U1

d.,.i

21 22 23 24 25 26 27 28 29

Separators, angles, cleats, gussets, shear connectors and other detail fittings Shelf angles Steel cores for composite columns Open-web steel joists, bracing and accessories Window sills Suspended ceiling supports Ties, hangers and sag rods Trusses and braced frames Steel stairs and handrails

[blank]

--

4-16

-.-

--

----

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

5. FUNDAMENTALS OF STRUCTURAL ENGINEERING The designer or engineer, responsible for preparing the design drawings, calculates the design loads a steel structure must support and then determines the size of each structural member required to support these loads. With an emphasis on beams, this chapter outlines the basic fundamentals of structural engineering so that the trainee steel detailer can gain an appreciation of how such steel members carry loads. Readers should refer to other specialised texts on structural engineering should they wish to get further insight into this and other related areas.

5.1

REACTIONS

A horizontal or inclined member that carries a transverse load and is supported at one or more points is called a beam. The forces acting at the supports are called reactions. The reactions resist the beam loads and hold the beam in equilibrium, that is, prevent it from moving in any direction. There are several common beam classifications which describe the type of supports used and hence the reactions involved: 1. A simple beam is simply supported at each end if the beam ends are free to rotate (Fig. 5.1 ). 2. A fixed beam is rigidly supported at both ends if the beam ends are prevented from rotating (Fig. 5.2). \.

3. A cantilever beam has one end fixed at a support and the other end free or unsupported (Fig. 5.3). A beam may also be described as cantilevered when one end overhangs a support and is free to deflect (Fig. 5.4). 4. A continuous beam spans continually over one or more intermediate supports (Fig. 5.5). A description of shear and bending moment follows: -->i

I

"

I

Rotation

Fig. 5.1: Simple beam (shear reaction at each end)

_/L

Fixed against rotation

[:1 ·······-----········· I

1

_=:_ ........................ - ...... _.........._.... ..

Fig. 5.2:·Beam fixed at both ends (shear and bending moment reaction at each end)

r:·j

·--~·F===========I

Fig. 5.3: Cantilever beam (shear and bending moment reaction at one end only)

Fig. 5.4 Beam overhanging one support (shear reaction only from supports)

Fig. 5.5: Continuous beam (shear reaction only from supports)

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

5-1

The two most common types of loads considered in design are dead loads and live loads. Dead loads remain essentially constant after they are applied. They include the weight of the beam, walls, partitions, floors and other material which make up the finished structure. Live loads include loads from occupants of the building, lifts, machinery, travelling cranes, moving vehicles and material or equipment stored in the structure. Other types of loads considered in design are wind loads, earthquake loads and impact loads caused by machinery and moving vehicles. A load that is evenly distributed over a length of beam is called a uniform load .. It may be uniform over the entire length of the beam or over a portion of the beam. Uniform loads are usually represented in textbooks by closely

wt

orw,.

11111101111111 Fig. 5.6: Unifonn load spaced vertical lines as shown in Fig. 5.6.

(

Wh_en a load is assumed to act~at one point, it is called a concentrated load. Although such loads are actually distributed over a short length of beam, the distance is usually small in comparison to the length of the beam, and

2000

\:.._

4000 120kN

Point A

~

""' rf. In

6000

Point B

,.;; ;,.,

Fig. 5. 7: Concentrated load --:±--- -

the load is considered concentra!~d. A single vertical arrow indicates the location and direction of the load as shown. in Fig. 5.7. Reactions from different beam loads are calculated using the laws of equilibrium. These laws are based on the observation that if a beam does not move as loads are applied, all forces acting on the beam are in equilibrium, ie, they are balanced. The laws are expressed by the following two equations: (5-1) (5-2)

Equation (5-1) states that the algebraic sum (indicated by the symbol 1:) of the moments of all the forces equals zero. A moment is the product of a force expressed in kilonewtons (kN) times a distance expressed in units of length (metres). This distance is the shortest distance (measured along a line at right angles to the force) to the point about which the moment is taken. The numerical value of a moment is expressed in units of force and distance such as kilonewton-metres. Equation (5-2) states that the algebraic sum of all forces equals zero.

5-2

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

'\.

5.2

SHEAR

When vertical or inclined loads are applied to a beam, they produce shear stresses. The shear stresses occur when one section of the beam tends to "slide over" an adjacent section. Fig. 5.8 shows an imaginary picture of a shear failure occurring between the right hand reaction force (RR} and the nearest load. The total vertical shear force is constant between the 80 kN load and RR (113 kN}. Therefore, any vertical cross section of the beam in this area is subject to a total shear force of 113 kN. Likewise, any cross section cut between the left hand reaction force (RJ and the 18 kN load is only subject to a total vertical shear force of 70 kN. Note that the total shear force at any section along the beam will vary depending upon the type of loading. In a simple span, the shear force is greatest at one or both reactions; hence it is at the ends of such beams that the shear must usually be investigated. Dividing the total vertical shear at any point along a beam by the area of the web at that point gives an average shear stress. It is usually assumed that only the web of the beam offers resistance to vertical shear. The area of the web is generally taken as its thickness times the total depth of the beam. In investigations of shear force stress in a beam web, the area of fastener holes through the web is not deducted. However, it is necessary to investigate the effect of reduction of the web area due to deep cuts or copes at the ends of the beam. The total vertical shear force at any point along a beam is equal to the algebraic sum of all vertical loads and reactions between that point and either end of the beam, including any load or reaction at the ends of the beam. Shear force diagrams graphically provide the magnitude of vertical shear force at any point along the beam.

Z

-" co

~

z

1000

-" 0

1000 ~1000 ""

2000

2000

6000 RL=?OkN

RR= 113 kN LOADING DIAGRAM

(a}

SHEAR DIAGRAM

(b} Fig. 5.8: Shear force diagram

5.3

BENDING MOMENT

Fig. 5.9 is an exaggerated picture of a deflected beam with several concentrated loads, simply supported by reactions RL and RR. Under this condition of loading, the top flange of the beam is subjected to compressive stresses which shorten it slightly. The bottom flange is stressed in tension, and is lengthened by the same amount the top flange is compressed. It is this shortening and lengthening of opposite flanges of the beam which accounts for the curved or deflected condition. Midway between the top and bottom flanges of a symmetrical section is the neutral axis where the stresses change from compression to tension. The intensity of the bending stress is zero at the neutral axis and increases to a maximum at the flanges. This increase is in direct proportion to the distance from the neutral axis. The bending stress (also referred to as "flexural stress"} at any point on the cross section of a beam is a measure of the intensity of the stress on an imaginary layer of steel of minute thickness. ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

5-3

Fig. 5.9(b) shows an enlarged portion of the same beam, at section Z-Z, with the beam to the right of the Z-Z cut taken away. Replacing this cutaway portion are the bending stresses imposed on the left-hand beam portion. These are represented as drawn to scale longitudinal internal forces, which are in contrast to the externally applied forces P1, P2, P3, RL and RR The distance between a compression force and an equal tensile force is termed a moment arm or couple arm. Each compressive force coupled with an equal tensile force forms a moment couple. Collectively, all these couples, beginning with the smaller values near the neutral axis and increasing to the maximum at the top and bottom of the beam, resist the internal bending moment (M) indicated by the curved arrow. Note that the stress is maximum at the top and bottom of the beam, where the flanges provide much of the total cross-sectional area of the structural shape. It is at these points of high stress that the steel member performs most efficiently in resisting bending. This accounts for the efficiency of the UB and UC shapes used as beams. If the same volume of steel were rolled into a square bar, its bending resistance would be much less. Even if it were rolled into a rectangular bar having the same depth as that of one of the beam shapes, its bending resistance would still be much less, because more steel would be located nearer the neutral axis, where the bending stress is very low. The maximum bending stress is dependent upon the: 1. Width-thickness ratio of the beam flange. 2. Depth-thickness ratio of the web. 3. Yield stress of the steel. 4. Unbraced length of the member. The calculation of bending stresses is beyond the scope of this book. However, the maximum bending stress has been ·determined for each rolled shape as a function of unbraced length. By multiplying this value by the section modulus of the shape, tables and charts have been developed which plot the moment capacity versus the effective length. These Tables and Charts are incorporated in the AISC Design Capacity Tables books (Refs. 2 and 3).

Ps

z

b RL

z

RR

_.. 7

i

(a)

z le

(Compression)

Neutral Axis

~(Tension) z (b) Fig. 5.9: Deflected beam

5-4

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

6. BOLTING 6.1

INTRODUCTION

The beams, girders, trusses, columns and other members which form a completed structure are designed to support certain loads. Each of these members must transmit its load through structural joints to supporting members. A joint requires a means of fastening - either bolts or welds. In addition, most structural joints require detail connection material, made of angles, plates or pieces of rolled beams. This chapter is concerned primarily with bolts, Chapter 7 will cover connections made by welds. Bolts are widely used for making connections in structural steelwork, especially field connections. An understanding of all aspects of the use of bolts is consequently vital to designing, detailing, fabricating and erecting steel structures. Although usually specified by an engineer, the selection of a bolt for use in a structural steel connection will need to have regard to a variety of factors including the: 1. Nature of the forces to be resisted. 2. Design capacity of available bolt types. (.

3. Amount of joint slippage desired. 4. Degree of flexibility/rigidity desired in the joint. 5. Cost of the installed fastener.

6.2

BOLT TYPES

The two basic types of metric bolt in use for structural engineering purposes in Australia are the: 1. Commercial (Strength Grade 4.6) bolt to AS/NZS 1111; and 2. High strength structural (Strength Grade 8.8) bolt to AS/NZS 1252. Commercial bolts are made of low carbon steel with mechanical properties similar to that of Grade 250 material. High strength structural bolts are made by heat-treating, quenching and tempering medium carbon steel. Accordingly, heating or welding a commercial bolt will cause no significant change in its properties, but either process will cause a significant degradation in the mechanical properties of high strength structural bolts .

..

Only a limited range of sizes of these bolts are used in structural engineering. The commercial bolt is commonly used in the following diameters: M12 - purlin and girt applications M16 - cleats, brackets (relatively lightly loaded) M20 - general structural connections, holding down bolts M24 - general structural connections, holding down bolts M30 - holding down bolts M36 - holding down bolts The high strength structural bolt is most commonly used in diameters: M16 - designed connections in small members M20 - flexible connections, rigid connections M24 - flexible connections, rigid connections M30/ M36 - larger sizes (M30, M36) of the high strength structural bolt should be avoided when full tensioning is required, since on site tensioning can be difficult and requires special equipment. Note that the prefix M is used to designate metric bolts with a thread complying with AS 1275.

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

6-1

The identification of the two different bolt and nut assemblies can be readily made from the bolt head and nut markings. An additional distinguishing feature is the larger bolt head and nut of the high strength structural bolt compared to the commercial bolt. Commercial bolts to AS/NZS 1111 are not normally supplied with a washer and therefore washers to AS 1237 are ordered separately if required. High strength structural bolts to AS/NZS 1252 are normally supplied as bolt/nut/washer assemblies. For further information on the design of bolts the reader is referred to the AISC publication "Bolting of Steel Structures" (Ref. 7).

6.3

BOLTING CATEGORIES

In Australia a standard bolting category identification system has been adopted for use by designers and detailers. This system is summarised in Table 6.1. Category 4.6/S refers to commercial bolts of Strength Grade 4.6, tightened using a standard wrench to a snug-tight condition (see Section 6. 7). Category 8.8/S refers to any bolt of Strength Grade 8.8, tightened using a standard wrench to a snug-tight condition in the same way as for category 4.6/S. Categories 8.8/TF and 8.8/TB (or 8.8/T when referring generally to both types) refer specifically to high strength · structural bolts of Strength Grade 8.8, fully tensioned in a controlled manner to the requirements of AS 4100 - see Section 6.7. The system of category designation identifies the bolt being used by its strength grade designation (4.6 or 8.8) and the installation procedure by a supplementary letter (S-snug; T-full tensioning). For 8.8/T categories, the type of joint is identified by an additional letter (F-fr'iction-type joint; B-bearing-type joint). It is most important to note that the high strength structural bolt may be specified in three ways: 1 . snug-tightened - category 8.8/S; 2. fully tensioned, friction-type-category 8.8/TF; and 3. fully tensioned, bearing-type - category 8.8/TB. The level of tensioning is the same for both 8.8/TF and 8.8/TB categories. In practice, 8.8/S category would mainly be used in flexible joints where the extra capacity of the stronger bolt (compared to 4.6/S category) makes it economical. It is recommended that 8.8/TF category be used only in rigid joints where a no-slip joint is essential. Note also that 8.8/TF is the only category requiring attention to the faying · surfaces. Design engineers' drawings and workshop detail drawings should both contain notes summarising the category designations. Table 6. 1: Bolt types and bolting categories

Bolting Category

Method of Tensioning

4.6/S 8.8/S

Snug

8.8/TF (friction type joint)

Full Tensioning

8.8/T

Minimum Bolt Tensile Strength (MPa)

Minimum Bolt Yield Strength (MPa)

400

240

830

660

.

Bolt Name

Bolt Standard Specification

Commercial

AS/NZS 1111

High Strength Structural

AS/NZS 1252

8.8/TB (bearing type joint)

6-2

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

6.4

DESIGN OF BOLTS

In any bolted structural connection, there are three fundamental modes of force transfer to be considered - two relating to the transfer of shear and one relating to the transfer of tension. These modes are: 1. Shear/bearing mode where the forces are perpendicular to the bolt axis and are transferred by shear and bearing on the bolt and bearing on the connected plies. 2. Friction mode, which is similar to the shear/bearing mode in that the forces to be transferred are perpendicular to the bolt axis. However the transfer of forces does not rely on shear and bearing. The frictional resistance of the mating surfaces is the prime factor in the force transfer mechanism: 3. Axial tension mode, when the forces to be transferred are parallel to the bolt axis. Often, the modes are combined, since in a large number of connections it is necessary to transfer both parallel and perpendicular force components. Typical connections subjecting bolts to shear forces only are splices in members, end connections to bracing members and connections of members to gusset plates in trusses. Bolts in tension are found in hanger connections and in bolted moment connections. The latter type of connection may also subject the bolts to combined shear and tension forces.

,Q.5

BOLT LENGTH SELECTION

The responsibility of selecting bolt lengths for each connection usually rests with the steel detailer. In selecting bolt lengths, consideration must be given to whether the shear plane cuts across the threaded or unthreaded section of the bolt. The advantages and disadvantages of both must be clearly understood by the steel detailer. Most connections are designed on the basis of threads being included in the shear plane. Where designers specifically require theads to be excluded, the steel detailer must take additional care when calculating bolt lengths to ensure this requirement is met. The following section discusses the background to this issue.

6.5.1

Plain Shank Lengths

Plain shank bearing lengths for each bolt type are defined in the relevant Australian Standards (AS/NZS 1111 and AS/NZS 1252) as the distance from the bearing surface of the bolt head to the last scratch of the thread. Ref. 7 provides tables of plain shank lengths for commercial and high strength structural bolts.

6.5.2

Threads Included in Shear Plane

For the case of threads included in the shear plane (Fig. 6.1) the average maximum grip (assuming a 5 ml)'l projection of threads through the nut) is given in Ref. 7. From this bolt lengths can be easily calculated.

LEGEND:a = thread runout

b = length of thread

ts= plain shank length t = nominal bolt length n = nut length I

b

-l

l+--------=g'--'----rip

t

w= washer thickness

I 5

w

Ag. 6.1: Threads included in shear plane ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

6-3

6.5.3

Threads Excluded From Shear Plane

For the case of threads excluded from the shear plane, the situation is as shown in Fig. 6.2. The critical dimension is t 1 , the thickness of the ply under the bolt head. Refer to Ref. 7 for examples of calculating bolt lengths.

LEGEND:a = thread runout b = length of thread ls= plain shank length t = nominal bolt length n = nut length w= washer thickness 6 = usually 3mm

b

grip

n

t

5

w

Fig. 6.2: Threads excluded from shear plane

To avoid having to calculate bolt lengths on each occasion where threads are excluded from the shear plane, a simple table, such as Table 6.2, can be prepared. Table 6.2 lists the correct bolt length for various combinations of grip and minimum external ply thickness. Note that the minimum external ply thickness is merely grip minus the critical thickness. The critical thickness is the thinner ply thickness (or ply thickness under the bolt head - if it is known) for the single shear case, or the sum of the thicknesses of the thicker external ply and all internal plies for the multiple shear case. Thus the table can be used directly for all shear cases. It is essential that in selecting bolt length for the case where threads are to be excluded from the shear plane, attention should be paid to the ply thicknesses as well as the total grip of the joint. This is an important consideration since bolts will normally be placed in joints from the more convenient side for the erector, or to provide nuts on the easier side for tensioning in the case of 8.8ff procedures. The following matters should be considered when detailing bolts with threads excluded from the shear plane: 1. Bolt length for the threads excluded case must be selected to provide plain shank in the shear plane for installation from either side of the joint. This usually results in longer bolts than would otherwise be required. 2. Due to the relatively long thread lengths of ISO metric bolts to AS/NZS 1252 and AS/NZS 1111, a bolt with sufficient plain shank to exclude threads from the shear plane may project well past the nut-washer assembly. This stickout can cause difficulty in installation because adjacent bolts in a connection may foul one another. The physical interference of bolts can often be relieved by installing the bolts in the manner shown in Fig. 6.3. However in joints where tensioning to AS 4100 is required (categories 8.SffF and 8.8ffB) it will not always be possible to apply the socket of an air wrench to the nuts of bolts with long thread stickout. 3. In joints with thin plies (e.g. 8 mm angle legs or 8 mm endplates), it is often necessary to use extra washers under the nut where threads are to be excluded from the shear plane in order to ensure that the nut does not run up to the end of the thread. 4. As the location of the plain shank relative to the shear plane position is critical for the threads excluded case, such a joint is very sensitive to bolt length selection. This means that bolts have to be selected usually in length increments of 5 mm and results in the stocking of a great number of different bolt lengths and the subsequent difficulty in distinguishing correct bolts for a particular joint on site. Alternatively, excessive 'stick-through' must be accepted. 6-4

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

.-

~

Table 6.2: Bolt lengths for M20 bolts to AS/NZS 1252 - threads excluded from. shear plane. Bolts above the line to be used with minimum of 1 washer under nut (* indicates 2 washers required).

;§

~

.L

GRIP(mm)

~ co

6 8

;!!:

10

~ ~

!!l ~

z~

!!lm m

I'"'

c

~

I'"'

m

:II

II.! ::c

12

E'

.§. ~

ll.

az r:c

14

~

24

::!!

26

:ii

28 30 32

g

34

0

36

z:

60

65

65

65

70

70

75

75

75

80

80

85

85

85

90

90

90 100· 100· 100 100100110·110· 110 110 110120•120·120 120 130 130 130140•140•140 140 140 150·

65

65

70

70

70

75

75

80

~o

80

85

85

90

90

90 100· 100· 100 100100110·110··110 110 110120·120·120 120 120 130 130140•140•140 140 140 150"

65

70

70

70

75

75

80

80

80

85

85

90

90

90 100· 100 100 100 100 110· 110 110 110 110 120· 120 120 120 120 130 130 140" 140 140 140 140

70

70

70

75

75

80

80 80

85

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120 130 130 140 140 140 140

70

70

75

75

80 80

80

85

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120 130 130 140 140 140

70

75

75

80

80

80

85

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120 130 130 140 140

75

75

80

80

80

&5 85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120 130 130 140

75

80 80

80

85 85

90

90

80

80

80 85

85

90. 90

80 80

85

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120

80

85

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120

85

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120 120

85

90

90

90 100 100 100 100 100 110 110 110 110 110 120 120

90

90

20

> z c

;ii;

60

18

22

z

1214~1s~"~~~~~M$~~~~~~oo~M$~OO~M~~ronMnnoo~M$~~

16

~

w

10

•When interpolating values, select longer bolt length. •Table is valid for both single and multiple shear cases.

90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120 130 130 90 100 100 100 100 100 110 110 110 110 110 120 120 120 120 120 130

90 100 100 100 100 100 110 110 110 110 110 120 90 100 100 100 100 100 110 110 110 110 110 120 100 100 100 100 110 110 110 110 110 120

38

100 100 110 110 110 110 110 120

40

110 110 110 110 110 120

I., '

Fig. 6.3: Bolt Installation to avoid fouling.

6.5.4

Thread Projection

AS 4100 requires that the length _of a bolt be such that at least one clear thread projects through the nut and that at least one thread plus the thread run-out is clear beneath the nut after tightening to either /S or bolting category. (Fig. 6.4)

rr

~~~~ * *

Min one thread (one pitch)

Fig. 6.4: AS 4100 requirements for thread projection.

The methods of calculation presented in Ref. 7 meet these requirements. The minimum projection through the nut of at least one thread pitch is intended to ensure that full engagement of the nut thread is achieved. While this is accepted good practice for /S bolting category, it is crucial with category in order to achieve the specified minimum bolt tension.

rr

The clearance under the nut is intended to ensure that a nut is never run up to the thread run out on the bolt which constitutes the end of the threaded portion of the bolt. If the clearance is not provided, the nut will not sit firmly against the washer and, in the case of category, the necessary turn-of-nut may not have been achieved.

rr

6-6

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

6.5.5

Available Bolt Sizes

Where possible a detailer should use bolt sizes that are readily available. Table 6.3 provides a summary of readily available commercial grade bolt sizes, ie. bolt diameter and length options. A similar table for high strength structural bolts is provided in Table 6.4. Table 6.3: Readily available commercial bolt sizes. Nominal Lengths ! (mm)

Diameter mm

45

40

x I x x x x x

M12 M16 M20 M24 M30 M36

55

50

x x x x

I

x x x x

60

65

x x x x x I x x x x x

70

80

x x x x x x x I x x x x x

90

I

x x x x x x

.

100

110

120

130

140

150

x x x x x x

x x x x x x

x x x x x x

x x x x x x

x x x x x x

x x x x x x

Usually supplied as full thread bolts

Table 6.4: Readily available high strength structural bolt sizes. Nominal Lengths ! (mm)

Diameter mm

45

50

55

60

65

70

75

80

85

90

M16

x x

x x

Ix

x x x

x

x x x x x I x x x

x x x x

x x x x x

x x x x x x x IX x x

M20 M24

x x

M30 M36

I

l
"

n

ii1 :> GI

480 20

2100

ii1

(opt) 40

~

(opt)gro~

~

2500

3580

t:r

n

1600

2100

410UB53.7 x 6540

j

65600/A

4-COLUMNS REQDAS DRAWN & NOTED MKD 1/A2,1/A5,1/82,1/85 4-COLUMNS REQDAS DRAWN & NOTED MKD 1/A3,1/A4,1/83,1/84

l'iD

"' 35

Reader's Note: "(opt)" indicates optional dimensions which are not essential for the fabrication of the steelwork but are useful to the steel detailer for detailing and checking purposes.

I IB co ~

·•. I

360 460

••

10.6 EXAMPLE OF DETAILING A MULTI-STOREY COLUMN To illustrate the method of detailing a typical multi-storey column, the column on grid-line location B3 of the building shown in Figs. 10.3 and 10.5 will be considered. The column section is a 310UC96.8 in the upper tier, a 310UC137 in the middle tier and a 31OUC158 in the bottom tier. It supports the roof and four intermediate floors and its base is at - 0500 level (TOC) ie. the top of the concrete footing is 500 mm below the 000 datum. The steel detailer will need to allow for grout (in this case 50 mm) when calculating the steel column length. It is oriented in plan with its web north-south and has a base plate 750 x 750 x 70 thickness, designed by the engineer. The splices are shown typically only on the column schedule, so the detailer will have to proportion them.

10.6.1 Column Detail Drawings The shop details of the column, in its three segments, would be prepared by the steel detailer. The first segment is shown in Fig. 10.6. The other two segments would be detailed in a similar fashion. The actual drawing would be to a composite scale. The following information is included on the drawings: 1. Column shaft sections and overall lengths. Note that the 50 mm grout dimension and the ground level are shown to facilitate checking. 2. Base plate size, including HD bolt holes. 3. Foundation, floor and top-of-steel-beam levels.

(

4.

Holing for the beam end connections.

5. Areas adjacent to the 8.8/TF bolt holes are marked to be left unpainted. 6. The erection marks of the column segments (suffixed (a), (b) and (c) in the column mark for the three segments). 7. The packers required at the splices (not shown in Fig 10.6 as this is the widest column segment - packers should be detailed in the adjacent segment as it will be narrower.) 8. Welding of the base plate to the shaft. 9. The NORTH mark to indicate column orientation on site. Note that the column web elevation is drawn as viewed from the east (ie from the right-hand edge of the plan drawing). The plan on the base plate is drawn with the column web in the north-south direction to correspond with the orientation on the plan drawing. The longitudinal dimensioning of the holes in the flanges is not given, since in this case the holes are in line with those in the web, where the longitudinal dimensions are given.

10.6.2 Beam End Connections ( '~

.

Before the column can be detailed it is necessary for the steel detailer to have some knowledge of the beam end. connections. This may1lel" done by the methods described in Chapter 9.

10.6.3 Splices The detailer also needs to detail the splices above the first and third floor levels (see Fig 10.3 for splice locations). The detail of the lower splice is shown in Fig. 10.7.

10.7 EXAMPLE OF DETAILING PORTAL FRAME COLUMN A column in ·a portal frame building with a crane gantry girder supported on brackets, is detailed in Fig. 10.4. It is assumed that all the necessary information regarding the rafter connection, crane bracket and column base has been provided by the designer. The following points should be noted for this type of drawing: 1 . A regular (not composite) scale should be used because of the amount of detail that occurs within the length of the column. 2. An elevation of the web of the column only is drawn. Views on the flanges are not necessary in this case since the required information can be given in the sectional plans and, for the flange holing, by the notes giving the hole cross centres, eg '2 holes 90 centres'.

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

10-7

~

TOC .. levels Roof

120 thk slab

4th

150 thkslab

Roof 0 0 N

v

3rd

do

2nd

do

1st

do ~

Ground I

f

1

2

3

4

ELEVATION ON GRID B

(

BASE PLAN

Fig. 10.5: Elevation and plan on multi-storey building 10-8

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

,-_-,

)> Cf)

0

i§ I

~

~

-

750x 50x70

~

~

~ m m I""

c

~ ;::

m

:II

U?

::c

~ c DI

0 0

"'

-

4-42 dia holes for M36 HD bolts

~

~... ~

260

~ ::

I

(')

i !

a

Q DI

c.>

i .a

'

-

Q

Ill

-·-

-

-·-·-·- ! ·----- -·- -----·-·-,~

-ii..... I

--·

~

--F ace

(opt)

4200(opl)

600 4x 140

250

70

70

35

(opt} 160-

A'j

1

rg-

Mkflgnonh

-0

~

vi o paint

it

g

---------- -·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-~1·-·

. ·- - -· I

·-·-· ·-·

..

a:!

- v 12

;

i

;

SECTION A-A

-

"'

~

c c

10-26 dia holes for M24 bolts

,a

~

g Bolts: M20 ] Holes: 22 dia UNO No paint within 100 mm of 8.8/TF bolt holes

ONE COLUMN REQD THUS MKD C/83 (a)

...

true and square

• 52500/A

- µ~

I

··-

~

--1

3770

I

~

Bearing surface ~tobecut

---~1,1" -·-·-·-·-·-·-·-·-·-·-·-·-·-·-·--·- -·-·-·-·-·-·-·-'·-·-·-·-·-·-·tI:: ··-·~·l·~·-1-"'" ---u :u ''

250

c

.

.

I

:::::::~::::

500 (opt)

?

~ :I

B-26 dia holes in each fig for M24bolts \

~·~

(opl)50g~

0

I

·-

Basefelate

9 l> c:

310UC15Bx 5180

I

~

Reader's.Note: "(opt)" indicates optional dimensions which are not essential · for the fabrication of the steelwork but are useful to the steel detailer for detailing and checking purposes. I ,

No paint

3. The sectional plans are drawn adjacent to the main elevation. They are located near the positions where the section cut-lines are located or properly referenced and positioned to suit the drawing layout. 4.

Separate strings of longitudinal dimensions are given for the different types of detail, ie one for the crane bracket and cleat, one for the girt cleats and one for the web holes. Running dimensions, as discussed in Section 9.4, could also have been used.

5. The dimensions start and end at the cut ends of the column section. 6. The six holes in the inner flange near the top (right) end of the column are dimensioned down from the top of the shaft, as are the four web stiffeners. These items are for the connection of the portal rafter and relate to the top end of the member, so no closing dimensions to the base are necessary. 7.

On the plan of the crane bracket a reference dimension of 400 mm is given in brackets. Since building spans and crane spans are nearly always in fairly round numbers (eg a building span of 12,000 m and a crane span of 11 ,200 m), the column centre to gantry girder centre will also be a round number (400 mm). However, in fabricating the bracket the shop needs to know the distance from the column face, ie 199 mm (allowing for a 201 mm half-width of the column). Reference dimensions are always given in brackets. They are not used directly by the shop, but are useful for reference and for checking.

321nom

1·

." '

.:

,

;

...,,,'" .,..,,'·' ...,., ......·'·i··• ...

~

.'

..,.,, "' g

,_

--

" "" ."". "" "' " .................. "

..

( \.

310UC137

"

...:!:.,....,,

": :140

g g

·1 90

250x3 packers

•j•

·-- ,_

Flange splices 250x12 PL

,,

.. ..ai. ..

Ends of columns prepared for bearing

g "• '

Web splices 150x10PL

'' ''

(

310UC158 Bolts: M20 GrB.B/TF

I.

327 nom

.I

Fig. 1O.7: Splice at first floor level, column C/83

10-10

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

10.8 ANCILLARY DETAILS 10.8.1

Shims

The shims furnished to the erector are for use in filling out the spaces allowed for field clearance at column splices and shear or moment type beam connections. These may be either the conventional kind, with round punched holes, or the "finger" type with slots cut through to the edge (see Fig. 10.8).

I+ +++I Conventional

Finger

Fig. 10.8: Example of shims

The conventional type shim is less expensive to fabricate, the finger type has the advantage of lateral insertion without the need to remove erection bolts or pins already in place. It should be noted that fabricators prefer that shims be listed on drawings and order bills.

10.8.2

Lifting Hitches

To assist the erector in handling columns at the site, it is customary to provide some means of attaching a lifting hitch. Fig. 10.9 illustrates several common types which have proved satisfactory. For columns with flange type splice plates, it is convenient to place lifting holes in the splice plates. Where universal columns are not furnished with splice plates, the most satisfactory location of a lifting hole is in the column web. While this hole reduces the column cross-sectional area slightly, it will seldom be of any significance, since the column is sized for loads from the floor below and the splice is usually located above the floor. Other devices shown in Fig. 10.9 are suggested solutions for box columns with top butt plates. In using the suggested arrangements shown, it will be necessary to determine: 1. the type and size of erection equipment to be used. 2. the capacity of this equipment. 3. the weight of th~ columns to be lifted. A design investigation must always be undertaken to assure a hitch capacity sufficient to support the weight of-the. ·column. -

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

10-11

"" .... 1111

....• •

1111

shackle and pin

1111

1111

: 1: ........... .JI

&J

l

-

• ~- ................ :-.. :~ •• •

--

by '

-

...••''

'

T

~

Ere~?

T

--.-••

y~

"

. ~

Columns with flange type splice plates; pin holes in splice plates.

v Column with no splice plates, pin hole in web.

•• .............. . ........-. .,--' .

'"r"'"'" .........

' ' '' ....................

'

.-- --·' '

Column with butt plate at top; pin holes in temporary pin plates.

Box columns with and without butt plates; pin holes in temporary pin plates. These plates may remain in place, providing they do not interfere with the upper shaft.

Fig. 10.9: Examples of lifting hitches

10-12

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

11. TRUSSES 11.1 INTRODUCTION Trusses are used in the roof construction of buildings of medium to large spans. They are able to support heavy loads on greater spans than beams or rafters made from universal sections. They are also used in footbridges, conveyor gantries, walkways, etc. Trusses may be of welded or bolted construction, depending on the fabricator's preferred production method. The decision to bolt or weld will also depend on whether the component can be transported to site in one or two sections or must be dispatched piece-meal for on-site assembly. The decision to weld or bolt trusses is usually made by the designers, however, it is not unusual for the fabricator to propose alternate options.

11.2 TYPES OF TRUSSES There is a great variety of layouts or configurations for trusses and girders. In the case of roof trusses the panel length is usually dictated by the purlin positions - and would thus range between 1800 mm and 2300 mm. In other applications the engineer will have chosen the panel lengths and overall depth to yield the greatest economy of steel usage. In all cases the principle of triangulation is used, ie the shape of the girder is made up of a series of adjoining - _ triangles. The members are all subject to axial forces, either compression or tension. The upper and lower longitudinal members of a truss or girder are called the top and bottom chords. The vertical and diagonal members, filling the space between the chords, are called the web members or verticals and diagonals. The points at which the member ends intersect are called nodes or panel points. The common point at which the member axes meet at a node or panel point is called a setting-out point (SOP). In theory the centroidal axes of members meeting at a node should all meet at a common point. However, in bolted angle construction the bolt lines are used instead of the centroidal lines, as shown in Fig. 11.1 (b). This makes for easier setting-out of the truss, both in the drawing office and in the shop. With welded angle trusses, gussets are often omitted and the web members welded directly to the chords, as shown in Fig. 11.1 (a). Here, the web members are 'nested', ie their ends are placed as close to each other as possible, but their axes do not meet at a common point. This practice is generally acceptable for smaller trusses, but should only be used with the consent of the designer. For larger trusses, where eccentricity of axes is unacceptable, gussets or plate extensions to the chord can be used, as shown in Fig. 11.1(b).

(

r

lrorT

(b)

(a) Fig. 11.1: Truss nodes

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

11-1

11.3 CHORD AND WEB SECTIONS The sections most commonly used in trusses and girders are shown in Fig. 11.2. All of them can be used in either bolted or welded construction.

r

T

(a)

(b)

LI

LI

(c)

H D (d)

(e)

0 (f)

Fig. 11.2: Chord and web sections

11.4 LAYOUT AND SCALES The first step in preparing shop details of trusses and bracing is the establishing of working points (ie SOP or intersection points [IP)). The distance between working points is then computed, as well as bevels which sloping working lines make with the horizontal or vertical. After working points and bevels are established and distances calculated, a layout is usually made of each joint. These may be placed on work sheets (not issued to the shop) to be later placed on the shop detail drawing to a smaller scale. They are sometimes made in advance at the time material is being ordered. The layouts of the joints are sometimes made directly on the shop drawing, instead of separate layout sheets, and they then become a part of the finished detail.

(·

The length of plain material is established by deducting the scaled distance from working points to each end of the member from the calculated distance between working points. Layouts, whether a part of a detail drawing or on a separate layout sheet, must be drawn accurately and to a large enough scale. This enables the setback of the plain material from the working point and the size of the gusset plates to be scaled from them. When the layout is on a separate drawing, a good scale is 1 :20. However, when the layout is part of the shop detail drawing, it is usually not practical to use a larger scale than 1:10. Scales smaller than this should not be used if size of material is to be determined by scaling. The scale used in laying out the working lines need not be the same as that selected for the details along these working lines. The more complicated the detail, the larger the layout scale must be to provide sufficient room for all the required dimensions, notes, marks, and descriptions of assembly pieces.

11.5 .. SYMMETRY AND ROTATION Fewer shop drawings will be reqiiired for detailing trusses, frames and bracing etc. when use is made of any symmetry in the framing. Because of symmetry, a shipping piece on one side of the building centre line may be exactly like another piece on the opposite side of the same centre line if rotated 180° in plan. In other cases such pieces may be "as noted" or "opposite hand" to one another. The details of the left hand portion can serve as the aetails of the right hand portion, thus cutting the required amount of drafting and shop layout work in half. When this method of detailing is used, it is always the left half of the "as drawn" shipping piece which is shown in the drawing. Refer to Section 3.3 for discussions on these issues.

11.6 DIMENSIONING Working dimensions, (ie those dimensions appearing on the erection plans, such as the centre-to-centre distance of columns) may be repeated on the shop details for ready reference in checking the details, and.for any subsequent study of the matching of adjoining shipping pieces. These working dimensions, if provided, are conspicuously placed outside of all other lines of dimensions. Next to the working dimensions are placed lines of dimensions locating intermediate panel points and other important reference points at or near the intersection of working lines. When working points lie outside of the shipping piece, dimensions giving the distance along the working lines, from the working points to reference points on the shipping piece are located prominently (see Figs. 11. 7 and 11.8). All of the detail dimensions can be laid out from these reference points. 11-2

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

I. •

11.7 NODE POINTS- BOLTED CONSTRUCTION When gussets are used for connecting the web members to the chords at the node points, the groups of holes for the bolts must be set out by the detailer. This is drawn roughly for each joint before the detail drawing is started. An example is given in Fig. 11.3, which shows that standard bolt pitches and end distances are used where possible and at least a 10 mm clearance is provided at member ends. In some cases clearances of up to 20 mm may be requested by the fabricator.

)'~

0

Top of gusset set back 10 mm

.._'\

(35)

2x130

2x130

~>.

1OOx75x8 UA 1r

' ''' ------,-'' '

\.•.

--·+·a--·-·-·-> C\I

(30)

./

+

:.---SOP---------., 0

·-·-·

·,_ ......

. ~

01

ll)

---~------------·-·

•• •

0

---·

Fig. 11.3: Set-out of node - bolted construction

The thickness of gusset plates is usually determined by the designer. In the interests of saving time and simplicity of fabrication, the following guidelines should be observed when setting out gussets: 1. 2. 3. 4.

Opposite edges should be parallel where possible. Adjacent edges should be at right angles where possible. Corners should not be sniped unless the included angle is less than 90°. The number of edges should be kept to a minimum.

In Fig. 11.4 gussets (a) to (d) are arranged in descending order of simplicity. They can all be cut economically, either by shearing or by machine gas cutting, from a large plate because they can be 'nested' when being marked off. In following the above rules it is sometimes necessary to depart from the standard bolt pitch, as for example in gusset (c) in Fig. 11.4, where the bolt pitch in the vertical line has been increased for the sake of having parallel edges to the plate. Using a uniform pitch would result in a shape as in (e). The fabricator should select the preferred procedure and instruct the drawing office as to the procedure to be adopted as standard. The shape shown in (!)employs standard minimum bolt pitches, but is an expensive gusset to make. In detail (g) the large number of bolts along the left edge implies a heavy load in the vertical member and consequently the gusset should be widened as shown by the dotted line to spread the load into a greater width of plate.

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

11-3

(b)

(a)

(d)

(e)

(c)

(f)

I

•

• ••• •• •••

• ••

(g) Fig. 11.4: Gusset shapes

11.8 NODE POINTS-WELDED CONSTRUCTION

\_

In light welded trusses, it is often possible to avoid using gussets and simply to land the web members on the chords and weld them. It must be ensured, however, that sufficient landing space is available for the welds to develop the force in the web member. In heavier trusses and girders the member centroidal axes should meet at a common point, as previously explained, unless designed otherwise by the engineer. Again, the steel detailer is required to lay out each joint to a large scale in order to determine the set-back of the member ends from the SOPs and to check whether sufficient landing is available to accommodate the required amount of welding. The length of each member is found by calculating the distance between SOPs and subtracting the end set-backs. Examples of such layouts are given in Fig. 11.5. Where only two web members meet on the chord and no gusset is used, as in detail (a), the centroidal axes can be made to intersect at a common point by placing the one web member behind the chord as shown. This, however, is an expensive detail as the truss has to be turned over to weld the second member. It should only be used after consultation with the designer and fabricator. Where eccentricity is acceptable, the layout shown in (b) can be used since the centroidal axes have no major significance. The backs of the angles can be used in calculating set-backs. Where several members are involved and concentricity is required, the set-outs in examples (c) or (d) are necessary. In (c) the gusset is butt jointed to the toe of the chord, whereas in (d) it extends behind the chord and is fillet welded.

11-4

AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

ASDH/01-1999

,·

,.,0 ------~

(b)

(a)

200

200

220

(c)

220

(d)

Bracings: 75x75x10 EA Chords: 125x125x8 EA All set back and gussets dimensions are scaled. Fig. 11.5: Layouts of nodes - welded construction In details (a) to (c) of.Fig. 11.5 the web members must clear the chord root radius by at least 5 mm, as shown in Fig. 11.6, and in (d) the top edge of the gusset should be set back 6-10mm from the top of the chord. In details (b) and (d) the chords and web members could be double angles instead of the single angles shown, and in (b) and (c)Jhe ·. chord could be a T-section. 0

.E E

~

cb

=:::;i;_j_

I

Fig. 11.6: Chord clearances

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

11-5

...... d> 1'-c~~

~

10050SoP

210

10.125M7Q,

' \

2010

2010.

> iii 9 > c:

!!!

~

z

!!!m m r

c

~

!fl

0 0

;ii;

i~ ~~:~~1401g(typ)

~ a

!fl

!! .... lg

\I~

SOP

~

NORTH

li!T 1'!t

Ill

:e

I

~Is

~ ~

1J...J

(J)

... 2 "' "'

~

~

.. ~ats I.~ I I :1'i1r~~· End

.... 1898

'"I

2000

,.I

!! ~

2000

••I

2000

,.I

Bolts: M20 Gr8.8/S Holes : 22 dla

0

~

I

Gul>SetS : 8 PL

2000 Symabt~

10000

°'~

SOP (top af chord)

/

4-holes 'A'

\:!·

100

c

Q.

cm

------·

~... ...:.... ..

Ir (J)

:c z>

~

4·holes'A'

:D

Cl!

.~,12".l,s c m

;

~ "'a=

..

"O

0

[

R" 200UB25.4 x 9292 OJA

(5, ,'.v

~...

~ 80

,v

av1so

152

2060

15Dx8 Fl.JC1451g

Haunches ex 250UB.25.4

End plates 150 x 16 PL

900

Holes 22 dla at 90 clc for M20 8.B/TB

2 • 90x6 FLx90 lg

12 - RAFTERS REQD MKD R1 126

..:::-3

A-A

CD

11·

3 3 CD

C' CD

r

18 All holes 1a dta

230

:1.

rn 1·-

! 1~~'~,~ ~ a 327

30

01

0 0

r -----·--- .1

"'

t

50X50xti EA x 327 lg

Cleats as on rafter

48 - FLY BRACES REQD THUS MKD K1 All welds 6mm cont. fillet weld UNO

fJ; 0

I

0

2250

2250 250UBS1.4x 5034 50500/A

~

I

~

~

"'

12 COLUMNS REQD M~D C1

232

160

1000

6. Intermittent welding is used to connect the eaves haunch web to the rafter. 7. In many cases the individual fittings are detailed separately and only shown as fitting items (with appropriate reference number) on the rafter and column detail drawing.

14.6 PRE-SET OF PORTAL FRAMES Due to their slender proportions, typical single-span portal frames are subject to fairly large deflections. If it were desired to counteract the deflection by means of a camber, this could be done by introducing a pre-set into the geometry of the frame, ie the angle at the end of each rafter (the eaves and the apex) could be adjusted to produce an upward camber of the frame. For example if a camber equal to the deflection from dead load only were desired, it would be necessary to raise the apex. In the example shown in Fig. 14. 7, the apex has been raised 30 mm. In Fig. 14.7(a) the dotted line represents the theoretical shape of the frame, ie the desired final shape under dead load. The solid line shows the shape to which the frame should be fabricated and provides for an upward apex displacement 'd' of 30 mm. The length 'c' of the rafter is the same both before and after application of load, so the column tops have to be displaced inwards by dimension 'g' which is found to be 9 mm. Fig. 14.7{b) shows the shape of the frame as fabricated. When the rafter in Fig. 14. 7 is detailed its apex bevel should be increased by 30: 9000 and the eaves bevel by the same amount plus a further amount of 9:5000 to allow for the column slope (ie. a total of 5:1000). This would. be incorporated into the detail drawing (Fig. 14.6) by making the apex bevel 303:1000 and the eaves bevel 305:1000. In practice, however, a pre-set is usually provided only in larger-span portal frames. It is the responsibility of the designer to decide whether a pre-set should be used or not. ·

g

f 0

i

..,"'II

I

__

... -·········--··

.. ----·-;

i i

0 0 C\I II

"

CD

i .c 0 0 0

(a)

"'II

(b)

.s:::

r-'

i

I

I.

a= 9000

i i

..

I

Given: a = 9000 b=2700 d=30 h =5000

c =J~ + b'=J9000'+ 2700' = 9396 f e' =J9396'- 2730' = 8991

=Jc'-

g = a - f = 9000 - 8991 = 9

Fig. 14.7: Portal frame pre-set

ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

14-7

i

"-

[blank]

14-8

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

ASDH/01-1999

.

15. STAIRWAYS 15.1 INTRODUCTION It is essential that the planning of stairways for buildings and other structures with floors or platforms at different levels be considered at an early stage of the steelwork detailing process. This will ensure that sufficient space and headroom is allowed, and that beams are properly located to support the stairs. Stairways are either required for general or access purposes or form part of emergency (eg fire escape) routes. The proportions, eg slope, width, size, etc are governed by considerations of safety and comfort and are largely standardised. Stairways, walkways and ladders must comply with AS 1657 - "Fixed, platforms, walkways, stairways and ladders- Design, construction and installation". Furthermore, where appropriate, stairway and landing design must comply with the Building Code of Australia (Ref. 11). The Building Code Of Australia has more stringent requirements particularly in regard to the allowable dimensions for risers and goings than AS 1657 and applies to stairs that form part of an emergency route in specific building types.

15.2 DESIGN OF STAIRWAYS 15.2.1 General Steel stairways are used mainly in industrial-type buildings and in mining, process and production plants, and are also often employed as fire escape routes or feature stairs in multi-storey buildings. With a growing trend to modularisation in all construction work, steel framed stairs are becoming increasingly common in commercial buildings as they can be quickly erect~d and used by construction personnel. First floor

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Stairs 800 wide. Treads 30 mm deep open grid. Landing 40 mm deep open grid. . Stringers 200 x 10 FL Rises 200 mm.

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Fig. 15.1: General arrangement of stairway ASDH/01-1999

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The designer will usually give the basic stair requirements, eg riser and going dimensions, slope, width, stringer size and type of stair treads and landings, in accordance with Ref. 11 or AS 1657. A typical example is shown in Fig. 15.1. In this instance, the stringers are 200 x 10 flats, but in larger stairs channels or rectangular hollow sections are often used. Note that the 200 mm rise used in this example is only acceptable under AS 1657, ie. it does not satisfy the BCA requirements. The descriptive terms used in relation to stairways are illustrated in Fig. 15.2.

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Going Tread

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Fig. 15.2: Stairway terminology

Slope is one of the most important characteristics of a stairway and is determined by the combination of risers and goings. At very steep slopes stairways are considered as ladders and are subject to different detailing requirements including such items as safety cages. The width of a stairway is measured as the clear distance between stringers or handrails. The minimum permissible widths vary depending on the stair use or purpose and it is for this reason that the width should always be specified by the designer. It is not the intention of this handbook to go into the various stair width and usage options that can apply.

15.2.2 Stringers The steel sections most commonly used for stair stringers are flats, channels and rectangular hollow sections (usually when dictated by architectural considerations). For larger spans the sections should be determined by structural requirements rather than geometric layout conditions. Cranks in stringers are invariably welded and treads ·· are bolted or welded to the inner face of the stringers. At the foot of a flight of stairs where a change in the direction of the stairway occurs, the top edges of stringers should. not be extended to a landing as shown in Fig. 15.3(a). since this represents a potential trip hazard. Channel stringers should have their ends.terminated with a vertical plate, as otherwise the projecting top flange could cause snagging and tearing of trouser legs. In outdoor situations and where corrosive liquids may be present it would be prudent to support the foot of the lowest stringer on a concrete plinth as shown in Fig. 15.3(b) in order to prevent corrosion of the fixing cleats and bolts. However, the bottom rise, measured from floor level, must be made equal to the remaining rises. Alternatively, the plinth may be made the full height and width of a step and thereby take the place of the bottom tread, as shown in Fig. 15.3(c). The preferred detail would normally be nominated by the designer.

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Fig. 15.3: Details at foot of stairway 15-2

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

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15.2.3 Treads The main consideration in selecting a suitable plate or grating for treads is the provision of a non-slip surface that will retain its effectiveness during constant and prolonged use. Treads for steel stairs are almost invariably made from raised pattern plate, concrete filled or open grating. Grating-type treads are not suitable for use by women wearing small heels, e.g. for office fire escape stairways. Minimum net thickness of plate treads are dictated by either the BCA {Ref.11) or AS 1657 and reference should be made to these documents. Treads should preferably have non-slip edges or nosings at least 25 mm wide with a raised pattern. Sighting edges are essential for treads made from grating. Nosing edges should have sharp corners ground off.

15.2.4 Landings Landings are used between flights to limit the number of risers per flight and at changes of direction. Specific requirements regarding the sizes and construction of landings are given in Ref.11 and AS 1657. Landings should be fitted with kick plates {possibly made from flats) that rise at least 100 mm above the flooring. They should extend around all open sides and under the first step of the rising flight of the stairway. This is particularly important on mining or processing plants where it is usual for kick plates to be provided on all elevated walkways.

15.2.5 Handrails and Balustrades {

Stairways and landings should be protected on both sides by a handrail, balustrade or wall. For certain widths of stairs a handrail must be provided on both sides. ·

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15.3 DETAILING The steel detailer will first prepare a rough large-scale set-out of the stair details as shown in Fig. 15.4. For the example shown a rise of 200 mm has been specified and the going dimension is 250 mm. Allowing for a 25 mm overlap of the treads, each tread will then be 275 mm wide. The sloping line connecting the nosings of the treads is called the pitch line. In this case it coincides with the upper edge of the stringer flat. Setting out points (SOP's) are established where the pitch line intersects the top-of-flooring levels at ground floor, landing and first floor. Note that at the landing level there are two SOPs, one for the lower flight and one for the upper. They are displaced horizontally by 50 mm, which is 10/8 times the landing grid thickness of 40 mm (the landing rests on top of the stringer). Note also that where the upper flight meets the first floor the stringers are cranked and a standard tread is placed level with the first floor. 275

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2500S0Ps Fig. 15.4: Set-out of stair details 15-4

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

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2000 SOP

250

SOP

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Fig. 15.5: Alternative set-out of upper flight

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The horizontal distance required to accommodate the upper flight is 275 + 2250 = 2525 mm. In cases where horizontal space is limited, this dimension could be' reduced to 2000 mm or 2250 mm by adopting the upper and/or lower details shown in Fig. 15.5. In this case, as indicated by the figure, a non-standard tread 250 mm long is required at the upper end and the 25 mm overlap of the first floor over the tread is lost, whilst at the lower end the stringers require an extra cross channel to support them. The landing edge need not be extended as in Fig. 15.4, however. Also shown on the set-out in Fig. 15.4 are the bolt holes for attaching the stair treads and the handrail (HR) posts (the dimensions are obtained from the suppliers' catalogues). Once these details have been sorted out, the shop drawing may be prepared. It is shown in three parts in Figs. 15.6(a), (b) and (c).

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From Fig. 15.6 it will be apparent that the tread and handrail standard holing is dimensioned only once since it is· typical. The treads and landing grid are shown chain-dotted. The treads will either be bolted to the stringers in the workshop so that each flight forms a separate unit or the treads and stringers will be despatched piece-meal for assembly on site. The landing grid will be despatched loose and be welded or clipped to the supporting angles at . · site. The handrailing will also be despatched separately. Note that the landing grid is supplied with an intEl!jral . kickplate with an overal~h~!ght of 150 mm. The upstand will be 150 mm minus the grid depth of 40 mm, ie 110 mm. At the landing all four stair stringers are supported on the 180 PFC channel cross beam, which in turn forms part of the support frame (see Fig. 15.6(c)). Regarding the shop work on the stringers, templates would be made for the skew-cut ends and the mitre joints would be butt-welded. The holing for the open grid treads would be marked off from a template, which would be moved progressively along the stringer slope in 320 mm increments.

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AISC: AUSTRALIAN STEEL DETAILER$' HANDBOOK

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ASDH/01-1999

AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

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As an alternative to open grid treads, treads made from floor plate may be used. The treads would then be directly welded to the stringers. With the resulting absence of bolting cleats, the treads are much shallower and the stringers can be reduced in depth. In the example in Fig. 15.8 they are 180 PFC channels. Figs. 15.7 and 15.8 show the tread set-out and the full shop detail of a stair made in this way. The stair has a slope of 40' and gives access to a platform decked with floor plating. The total rise is 2300 mm, yielding 12 tread rises of 191.7 mm. The going of 228.4 mm is slightly less than the 250 mm of the previous example, but is considered sufficient for industrial use. The handrail standards placed normal to the slope of the stringers are cheaper and stiffer than vertical ones and are acceptable in an industrial environment.

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AISC: AUSTRALIAN STEEL DETAILERS' HANDBOOK

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16. DETAILING FOR ECONOMY 16.1 INTRODUCTION The most important requirement of any structure is that it should be able to support the applied loads safely. The loading on most typical structures would be the weight of the structure itself, the weight of the cladding, floors and other permanent attachments and the superimposed or live loading, eg floor live loading in a multi-storey building, wind loading, dynamic loading from machinery, etc. In most industrial structures, where aesthetic or architectural considerations are not a major consideration, the next most important requirement is economy of construction. It is obvious that the owner would wish to have a safe structure at the lowest reasonable cost. The designer of the project has the responsibility of meeting the requirements of safety and economy. In the design, the designer will not only ensure that the structure will support the applied loading with a suitable margin of safety, but will also aim at using the least appropriate amount of material and specify details of construction that are simple and easy to carry out. It is in the area of simple, cost-effective details that the steel detailer can assist in achieving maximum overall economy and ensuring that steelwork remains an efficient fonn of construction. The most costefficient structure is not necessarily the one employing the least amount of steel. Simple detailing has a significant impact on the overall construction cost. I

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This chapter presents many practical aspects of detailing where economy can be gained in the fabrication and erection of steelwork. Much of the advice given is based on common sense and may appear obvious to the reader, but the points discussed are the result of many years of experience gained by fabricators in their quest for cost savings. For more detailed information the reader is referred to AISC's "Economical Structural Steelwork" (Ref.12) and Steel Construction Vol. 30 No. 2 "Costing of Steelwork from Feasibility through to Completion" (Ref. 13).

16.2 COMMUNICATION To meet the objective of efficient detailing the maintenance of a clear line of communication between the designer and the steel detailer will be of great assistance. Their respective activities are carried out in different offices, often in different finns and sometimes even in different countries. It is essential that the steel detailer has the opportunity to discuss freely with the designer any matters lacking clarity. The steel detailer should also be at liberty to suggest modifications that could lead to simplification. An interchange of ideas will often lead to a more efficient solution.

16.3 ECONOMY IN THE USE OF MATERIAL On a dollar-per-tonne basis, steel is a relatively expensive material and it therefore helps to buy it at the lowest price. Most fabricators purchasetheir material through steel merchants or steel service centres. On very large projects, involving · bulk purchases of material, a fabricator may purchase direct from the mills. In both instances base prices per tonne are quoted for a certain quantity of any particular section, with discounts offered for larger orders and surcharges added for non-standard lengths. Price extras are of course also applicable to non-standard grades of steel. A structure should preferably be designed using a standard grade of steel (Grade 300) and should not contain an unnecessarily large variety of section sizes nor have excessive member lengths. Wastage (or off-cuts)should be kept to a minimum. The steel detailer should be aware of the standard steel stock lengths supplied by the steel manufacturer. These are given in their product catalogues (eg Ref. 4). Regarding the use of plates, a large range of thicknesses up to 50 mm is available. The range of preferred thicknesses is 5, 6, 8, 10, 12, 16, 20, 25, 28, 32, 36, 40, 45 and 50 mm. Standard widths and lengths are given in the steel manufacturer's product catalogue and in the AISC Economical Structural Steelwork book (Ref. 12). It is most important that large plate elements, such as tank shell plates, be detailed so that they can be cut from standard sizes with a minimum of wastage. Smaller plate components, eg gussets, may be cut from scrap, but where a large number are required they should be cut from standard plate sizes. Random splicing of sections and plates by welding, that is the introduction of splices at any point within a member in order to use up short lengths of section available, is discouraged and should only be done with the agreement of the designer. In any case, the extra cost of welding should be appreciably less than the savings in scrap before this approach is adopted.

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16.4 RATIONALISATION OF MEMBER SIZES AND REPETITION OF DETAILS The more identical or nearly identical members there are in a structure, the greater will be the speed of production and the saving in fabrication cost. The rationalisation of member sizes and the repetitive use of identical details are thus important aims. On a typical floor layout, for example, the designer may have called for a variety of different beam sizes, including possibly different masses/metre for the same serial size. There are cases where worthwhile savings can be made by actually increasing some of the smaller sizes to match those of larger beams, thus simplifying the material ordering task and reducing the number of different beams to be detailed. The net cost saving is for the fabricator's benefit and the extra cost of the material should not be passed on to the owner. Similar savings could be made by rationalising section sizes used in trusses and bracing systems. The use of repetitive details is also very effective. Two or more beams or bracing members of the same size may have different end reactions and therefore require different sized end connections, or similar columns may need slightly different base plates. In such cases it is possible to achieve repetition of detail by increasing the sizes of the smaller end connections or base plates to match those of the larger. The result is simplification of detail drawing, quicker throughput in the shops and especially a lesser likelihood of error in assembly and erection. Within reasonable limits such savings usually outweigh the cost of the additional steel. Another .means of simplification is to make members symmetrical about their mid-length wherever possible. For example,·· main beams can be simplified by ensuring that the incoming secondary beams are arranged symmetrically, thus facilitating shop marking-off and allowing the beam to be erected either way round.

16.5 STANDARDISED DETAILS The use of standardised beam end connectiO(IS, column base plates, etc, contributes significantly to savings in time and labour both in the drawing office and in the workshop. Examples of such details, giving layouts and load capacities of typical connections, are provided in AISC's "Standardized Structural Connections" book (Ref. 1). Shop fabrication is speeded up through the frequent use of common standard details. Even where non-standardised connections are used, it should be ensured that all the steel detailers in the company use the same kind of detail or connection in a particular situation, and especially in the design of a single structure. Consistent company standards will greatly promote production efficiency in the workshops.

16.6 ACCURACY IN DETAILING The need for accuracy in the preparation of drawings was emphasised in Chapter 3. This applies especially to shop detail drawings and accurate working drawings are a most important factor in achieving overall economy of fabrication. If, for example; a beam detail relates to six identical or similar beams in a building, a single error on the drawing is repeated six times in the workshop. The error may be minor, such as the incorrect location of a group of holes, or a major one where the overall length is incorrectly specified, but in either case the cost of rectification will be far greater than the cost ofC:liecking the drawing in the first instance. The cost implications are far more serious when errors are discovered only during erection on site, as does often happen, and the defective parts have to be returned to the shop for reworking. The thorough checking of all detail drawings is thus of the utmost importance.

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16.7 FABRICATION 16.7.1

General

The detailing of steelwork should be such as to allow the parts to be fabricated as easily and quickly as possible. This may seem self-evident, but it must be emphasised that the shop detailer is able to influence production costs significantly by using straightforward details and connections and by employing many other time and money saving procedures. The management of any fabrication company should inform its staff of its preferred manufacturing procedures. Smaller firms will often opt for welding of shop connections, whereas larger organisations with computer numericcontrolled (CNC) beam drilling and punching lines will obviously prefer bolting. A guide should also be given as to the maximum size of component that can be handled in the shops. This will be governed by space limitations, available crane capacities and transport facilities. The steel detailer must be familiar with all aspects of the fabricator's capabilities and take these into consideration when detailing the steelwork. When it comes to the choice between shop welding and shop bolting, however, the designer's requirements must be taken into account. There may be overriding reasons, such as aesthetics, corrosion resistance, protection against fatigue failure, etc, why the designer prefers either welding or bolting.

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16.7.2 Fabrication Procedures The fabrication of steelwork consists of cutting the members to length, drilling or punching the necessary holes, cutting beam flange or web notches where required, welding or bolting on end connections and other attachments, forming splices in long members, assembling trusses and, finally, shop painting. The cutting and hole-forming operations can be done on the production line in shops so equipped, but the other operations are all off-line activities requiring special attention that are more costly. The greaterthe amount of work that can be done on the drilling or punching line, the lower the labour input. Further discussion on fabrication procedures is given in Appendix A.

16.7.3 Beams and Columns Rolled universal sections, as used in beams and simple columns, make up a large proportion of most steelwork projects. The beam to be prepared on a production line only requires more holes (not only in the beam itself, but also in the end plates and web cleats to be attached to it), but overall savings are gained because of the faster rate of production. The attachment of cleats to a beam is more easily achieved by bolting than by welding and can be done by less highly skilled labour. It is sometimes not' possible to fully attain a clear-cut process of just holing (and no welding) or welding only (and no holing), but the steel detailer should be aware of the implications and adopt the detailing procedure t>est suited to the workshop's production methods. · ( '·

Column base plates .are usually welded to. the shaft. The base should be kept as simple as possible - a thick,. unstiffened base plate is far cheaper than a thin plate requiring stiffeners or gussets. Where stiffeners are required, as on moment-resisting_l:/;~ses, as few plates as possible should be employed. Column splices should be kept to a minimum. In multi-storey buildings the column shaft will usually extend through three or even four storeys. The splices are nearly always site bolted, but welding may be used if it can be shown to be cheaper. The abutting ends of the column shafts must be accurately sawn, milled or otherwise finished for direct bearing and load-transfer. The amount of splicing material - splice plates and bolts - can then be reduced substantially, resulting in both workshop and site economies. In rigid-frame construction, where the beam ends are rigidly welded or bolted to the columns, the column web and flanges often require strengthening by welded stiffeners to resist the transfer of beam flange force into the column. Such stiffeners require accurate fitting and are expensive to install. Economy can be achieved either by using a heavier column section that needs no stiffening or by analysing the existing column section more carefully to find whether stiffening could perhaps be avoided. In either case, reference should be made to the designer to see whether these alternatives are acceptable.

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16.7.4 Welded Plate Girders Welded plate girders consist of a web plate and two flanges welded together to form a large I-section. The assembly is done in a jig where the flanges are held against the web and welding is done by an automatic submerged arc welding process. Savings can be made by using preferred plate thicknesses and widths for the webs and flanges, by employing web stiffeners only when they are needed and by avoiding unnecessary splices in the web and flanges. The use of one sided stiffeners to avoid having to turn the girder over to weld on the other side obviously saves time and labour. Vertical stiffeners may be stopped short of the bottom flange by a distance equal to four times the web thickness, thus obviating the need to cut the stiffeners accurately to length. Matters relating to web stiffening should be referred to the designer, unless the details are clearly shown on the drawings. The drilling of holes in plate girders is usually carried out after the flanges and web have been welded together. This brings with it the difficulty of moving such a heavy piece to the drilling line or alternatively moving portable drill rigs to the girder. Holing of the girder can be avoided altogether by welding pre-drilled end plates and web cleats to the girder section.

16.7.5 Trusses Whether trusses should be of welded or bolted construction could depend on the preferences of the designer or the fabricator,. Workshops specialising in CNC drilling or punching operations will choose bolted construction, which offers the advantage of rapid component production and easy assembly. Others will choose welding and will provide the necessary jigs to facHitate assembly. With welded trusses it is beneficial to have all of the web members connected to the same side of the chords or chord gussets to avoid having to turn the trusses over for welding on the other side. Should this aspect not have been considered by the designer, the steel detailer should offer suitable alternatives. It is obviously cheaper to avoid using gussets and to weld the web members - and these should preferably have single angles - directly to the chords, but the chords need to have sufficient depth to allow an adequate lap to be achieved. Angles with a long vertical leg or T-sections with a deep web are suitable for use as chords. See Chapter 11 for further comments in this regard. If welded construction is used, the holing of members should be avoided. Cleats, end connections and other fittings, already drilled, should be welded on after completion of the truss assembly.

16.7.6 Gussets Advice on the proportioning of bolted gussets is given in Chapter 11, where simple rules for achieving economy in layout are presented.

16.8 BOLTING The subject of bolts and bolting-is covered in detail in Chapter 6, but certain aspects relating specifically to economy are discussed below. The cost of a bolted connection is made up of the following: 1. The cost of the bolts themselves. 2. The cost of forming the holes for the bolts. 3. The cost of installing the bolts. 4. The cost of inspection, when required. The two main types of bolt used in the Australian fabrication industry are the Grade 4.6 mild steel commercial bolt, and the Grade 8.8 high stregth structural bolt. The latter bolt can be used as snug tightened (8.8/S) or fully tensioned either as a bearing bolt (8.8/TB) or friction grip bolt (8.8/TF). The relative price ratios, based on kN shear carrying capacity, of these three bolt catagories, including installation and inspection (where applicable), but excluding holeforming, based on M20 x 70mm bolts are approximately as follows: •

Grade 4.6/S : 1.6

•

Grade 8.8/S : 1.0

•

Grade 8.8/TB : 2.0

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The Grade 8.8/S bolt has factored shear and direct tension resistances of almost twice those of a Grade 4.6 bolt. It is therefore the most efficient fastener on an installed cost basis and would be a suitable choice for a job with a high proportion of large, fully-stressed connections. In most structures, however, many of the connections contain only two or three bolts and it is obviously not possible to halve their number since two is the minimum number used for practical reasons. Discretion must therefore be used in deciding on the bolt grade for a particular job. The Grade 8.8/TB and 8.8/TF bolts are relatively expensive. The purchase price of the bolt is the same as 8.8/S but the specialised installation procedure and the need for subsequent inspection add to the cost. These bolts are only specified when their use is clearly necessary, e.g. in slip-resistant (ie friction-grip) connections and in connections where large direct-tension forces are induced in the bolts. The essential points to be considered in the economical design and detailing of bolted connections are:1.

Standardise as much as possible for a project.

2.

Adopt simple details.

3.

Only one bolt diameter and one bolting category should be used in smaller structures. More variety may be justified on a larger structure, but different diameters or categories should be used in accordance with a predetermined philosophy.

4.

Only one diameter of bolt should be used in any single connection to facilitate the operation of punching or drilling holes, regardless of the size of the structure.

5.

Arrange for a minimum number of field connections by making large sub-assemblies in the shop.

6.

Bolts in double shear are markedly more efficient and thought should always be given to arranging the connection details accordingly if practicable.

7.

If possible, avoid bolted connections with a large number of bolts in line parallel to the force, otherwise reduction in bolt efficiency will result. Joints less than 300 mm between first and last bolt are 100% efficient, while longer joints are increasingly less efficient.

8.

The low design capacity of the 4.6/S bolting category means that it is generally restricted in usage to lightly loaded cleat, bracket or bracing connections.

9.

The advantage of the 8.8/S bolting category lies in its high design loads and the fact that only snug tightening is required. This bolting category is the most efficient on a cost-in-place per unit capacity. Its use is normally restricted to flexible (simple) connections. It is the most commonly used bolting category.

1o. Friction joints 8.8/TF are not very cost efficient and should only be used in joints where slip prevention is a necessity. Bearing joints 8.8/TB are much preferable on a cost basis. 8.8/TF and 8.8/TB categories are recommended for rigid connections. .. 11 . Try not to mix 8:8/S and 8.8/T bolting categories on the job, but where it is unavoidable arrange the connection details to a predetermined philosophy.. 12. For economy in bolt numbers it may appear desirable to exclude threads from the shear plane. However, practical reasons·outlined in Chapter 6 dictate that usually threads are considered included in the shear plane, · unless detailing of the bolts indicates exclusion is certain. 13. Corrosion protection of the bolts should be matched to the end use of the structure.

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16.9 WELDING Chapter 7 deals with welding from the point of view of joint and weld types, edge preparations, electrodes, weld strengths, etc, but additional aspects relating to the economics of welding are given here. In comparison with bolting the process of welding is expensive, so the amount of welding should be kept to a minimum. This can be achieved, firstly, by reducing the number or total length of welds to a minimum and, secondly, by using welds of the smallest practical size consistent with strength requirements. In general, the instruction 'weld all round' should be avoided except when such welding is really necessary. Means of reducing the total weld length include the following:

1. On simple column base plates, using a fillet weld on the outer face of each flange and short fillets along the web of the column section instead of welding all round.

2. In the case of manual fillet welds, using intennittent welds instead of continuous ones, where permissible. 3. When connecting lattice girder diagonals to the chords, welding along the two sides only and not across the ends of the diagonals. The volume of weld metal deposited can be reduced by not over-specifying the weld size. For example, doubling the size of a fillet weld doubles its strength, but requires four times as much weld metal. It is therefore particularly importanUo keep fillet weld sizes down to a practical minimum. It is also cheaper, strength for strength, to use a smaller, fillet weld of greater length than a larger one of shorter length. Weld metal in butt joints can be reduced by specifying incomplete instead of .complete penetration welds, but again this can only be done when consistent with strength requirements specified by the designer. Multi-pass welds are much more expensive than single-pass welds. The largest single-pass' fillet that can be !aid in the downhand position is 8 mm and the steel detailer should be aware of the cost implications when specifying larger fillets. Fillet welds should be used in preference to butt welds where this is feasible since the latter usually requires edge preparation of at least one of the pieces being joined. However, fillet welds larger than 12 mm to 16 mm are very costly and in this case either complete or incomplete penetration butt welds should be considered. Weldments should be detailed so that all or most of the welding can be done in the downhand position. Welds should also be located in such a way that it is not necessary to turn the workpiece over for welding the other side. Suitable clearance or access should be allowed for the electrode during welding. Stiffeners or other fittings that are located close to each other or to other protruding parts restrict access and should be avoided. In a right-angled joint it should be possible for the electrode to be held at an angle of 30° to 45° to one or another of the faces.

A fillet weld laid by an automatic process can be more cost-effective than a manual weld because of the higher speed of deposition and increased penetration, with the deeper penetration allowing a smaller weld size to be used.

16.10 TRANSPORTATION The detailer must also be aware of any transport restrictions which may limit the overall, length, width or height of a member, truss or frame. State road authorities will dictate the legal limits on length, width height and weight of truck loads. These may be extended beyond these legal limits by obtaining permits from the authority which may require the load to be escorted. This will generally involve additional transportation costs and must be discussed with the fabricator before detailing oversized components. Another situation that may restrict the size of detailed components is when the job is to be sea freighted and therefore containerised. Each component therefore must be carefully detailed to ensure it will fit into a standard sea transport container.

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16.11 ERECTION Compared with work carried out in the workshop, erection work at site tends to be less efficient because of factors such as less stringent supervision, the influence of bad weather, untimely steelwork deliveries to site, the working height above ground level and the slow operation of erection cranes. The steel detailer is, however, able to reduce some of these effects by taking certain precautions in the preparation of the details. Three major factors are under the steel detailer's control and will help erection to proceed easily and quickly, namely: 1. A reduction in the number of members to be erected. 2. Simplification of site connections. 3. Minimisation of the number of bolts and the amount of site welding. The number of members or pieces to be placed should be kept to a minimum because of the time required to attach each member to the crane hook, lift it, bolt it into position in the air and return the hook to the ground for the next lift. The alternative is making up fairly large pieces in the shops, this is generally more economical than assembly on site provided the sizes are kept within normal transport limitations. The maximum size of load not requiring special police escort is about 18 m long by 3 m wide by 2 m high. The connections should be simple, with a minimum number of bolts and proper access for bolt insertion and t.ightening. Safety of access for the erection crew must also be considered - site erection is one of the more dangerous activities in steel construction. Erection tolerances should be such that members can be swung into position without undue risk of jamming. The provision of seating cleats under beam ends will facilitate the erection of heavy beams and girders. If not actually designed to transfer load, they should be supplied to assist in the location of the beams until bolting is completed. Likewise, site-welded connections should always be provided with location cleats welded or bolted to one of the mating parts and with holes for temporary bolting during welding. Beam end connections using seating cleats, angle cleats and web side-plate connections are easier to assemble than those with welded end plates. The latter are less flexible in fit-up. All pieces that are identical and therefore interchangeable in the structure should be given the same erection mark in the shop. This will save the erector having to find a particular part with its unique mark when any one of the other identical pieces would fit. As mentioned in Section 16.8, it is advantageous to use only one kind of bolt in a structure. However, this ideal cannot always be realised because of the different sizi:is of the various connections. Main connections generally use M20 bolts whereas purlins, girts and small fittings only require smaller and often specialist bolts.

,· (

Bolted end connect\ons that transfer moment, such as portal frame haunch connections and rigid beam-to-column connections, should be detailed to provide adequate clearance for full tensioning of the bolts if 8.8/fB or 8.8/fF bolts are required. Where beams on ei!h~ s_ide of a supporting beam or a column web connect through common bolts, the steel· detailer must make provision for the beams to be erected independently to save the erector the trouble of having to hold both beams in the air whilst the bolts are fitted. Seating cleats may be used to overcome this problem. When beam or girder ends are connected to column webs, and especially when the column depth is small (as in the case of small universal sections), there is often a difficulty in fitting the beam into the confined spaces of the column webs. If the columns cannot be sprung apart, the beam will have to be lifted above the tops of the columns (or above the next splice position) and lowered down the web of the columns. In such cases it must be ensured that there are no welded web stiffeners or other obstructions that will prevent the beam from being lowered.

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17.REFERENCES 17.1 Australian Standards AS 1100

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Technical Drawings AS 1100.101 - General principles AS 1100.201 - Mechanical engineering drawing AS 1100.301 -Architectural drawing AS 1100.401 - Engineering survey and eng. survey design drawing AS 1100.501 - Structural engineering drawing AS 1101 Graphic symbols for general engineering AS 1101.3 Welding and non-destructive examination AS/NZS 1110 ISO metric precision hexagon bolts and screws AS/NZS 1111 ISO metric hexagon commercial bolts and screws AS 1163 Structural steel hollow sections AS 1170 Minimum design loads on structures AS 1170.1 Dead and live loads and load combinations AS 1170.2 Wind loads AS 1170.3 Snow loads AS 1170.4 Earthquake loads AS 1237 Flat metal washers for general engineering purpose (Metric series) AS 1252 High strength steel bolts with associated nuts and washers for structural engineering AS 1275 Metric screw th reads for fasteners AS 1397 Steel sheet and strip - Hot-dipped zinc-coated or aluminium/zinc coated AS 1548 Steel plates for pressure equipment AS/NZS 1554 Structural steel welding AS/NZS 1554.1 Welding of steel structures AS 1554.2 Stud welding (steel studs to steel) AS 1554.3 Welding of reinforcing steel AS/NZS 1554.4 Welding of high strength quenched and tempered steels AS/NZS 1554.5 Welding of steel structures subject to high levels of fatigue loading AS 1594 Hot-rolled steel flat products AS 1627 Metal finishing - Preparation and pre-treatment of surfaces AS 1657 Fixed platforms, walkways, stairways and ladders - Design, construction and installation AS/NZS 2312 Guide to the protection of iron and steel against exterior atmospheric corrosion AS 2327 Composite structures AS 2.::3?.7 .1 Simply supported beams AS/NZS 3678 Structural steel - Hot-rolled plates, floorplates and slabs AS/NZS3679 Structural steel AS/NZS 3679.1 Hot-rolled bars and sections AS/NZS 3679.2 Welded I sections AS3828 Guidelines for the erection of building steelwork . AS3990 Steelwork for engineering applications AS 4100 Steel structures AS/NZS4600 Cold-formed steel structures

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17.2 Other References Publications referred to in this Handbook: 1.

AISC, "Standardized Structural Connections", 3rd edition, Australian Institute of Steel Construction, 1985. AISC, "Design Capacity Tables for Structural Steel, Volume 1: Open Sections", 2nd edition, Australian Institute of Steel Construction, 1994 (and Addendum No.1, 1997). AISC, "Design Capacity Tables for Structural Steel Hollow Sections", 1st edition, Australian Institute of Steel Construction, 1992. BHP Steel, "Hot-rolled and Structural Steel Products", 98 edition, BHP Steel, 1998. The Institution of Engineers Australia, "AS CZ1: The Australian Engineering Drawing Handbook", Parts 1 & 2, The Institution of Engineers Australia, 1976, 1997. AISC, "A Guide to the Requirements for Engineering Drawings of Structural Steelwork", Steel Construction, Vol 29 No 3, Australian Institute of Steel Construction, September 1995. Firkins, A. & Hogan, T.J., "Bolting of Steel Structures", 3rd edition, Australian Institute of Steel Construction", 1990. Hogan, T.J. & Thomas, l.R., "Design of Structural Connections", 4th edition, Australian Institute of Steel Construction, 1994. BHP-BP, "Lysaght Zeds and Gees purlin and girt system - Limit state capacity tables and product information", BHP-Building Products, 1999. .· Stramit MBP, "Stramit Purlins & Girts - Product Technical Manual", Stramit Metal Building Products, 1999. ABCB, "Building Code of Australia", Australian Building Codes Board, 1996. AISC, "Economical Structural Steelwork", 4th edition, Australian Institute of Steel Construction", 1997. Watson, K.B., Dallas, S., Van Der Kreek, N. & Main, T., "Costing of Steelwork for Feasibility to Completion", Steel Construction, Vol. 30 No. 2, Australian Institute of Steel Construction, June 1996.

2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

17.3 Further Information Further information on steel detailing can be obtained Jrom: • • • • • • • • • • • • • • •

AISC(USA), "Detailing for Steel Construction", American Institute of Steel Construction, 1983. AISC(USA), "Compu~er Detailing System Tools for Shop Use", Proceedings, National Steel Construction Conference, Chicago, American Institute of Steel Construction, 1997. AISC(USA), "Structural Steel Detailing", Anierican Institute of Steel Construction, 1971. Benton, R., "Basic Structural Detailing", Longman Scientific & Technical, 1989. CISC, "Fundamentals orstructural Shop Drafting", Canadian Institute of Steel Construction, 1982. Goetsch, D., L., "Structural Drafting", Delmar, 1982. Hayward, A. & Weare, F., "Steel Detailers Manual", BSP Professional Books, 1989. Kamel, A.Z., "Steel Detailing in CAD FormaVBook and Disks", John Wiiey &Sons, 1995. MacGinley, T. J., "Structural Steelwork Calculations and Detailing", Newnes Butterworth, 1982. Maclaughlin, D., "Structural Steel Drafting", Delmar, 1997. Newman, M., "Structural Details for Steel Construction", McGraw-Hill, 1987. SAISC, "Southern African Structural Steelwork Detailing Manual", The Southern African Institute of Steel Construction, 1994. Schuster, J. W., "Structural Steel Fabrication Practices", McGraw-Hill, 1997. Weaver, G. L., "Structural Detailing for Technicians", McGraw-Hill, 1974. Weaver, R., "Structural Drafting", Gulf, 1977.

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Appendix A. FABRICATION OF STRUCTURAL STEELWORK The flexibility of a structural shop is its most notable characteristic. No other type of industrial shop is called upon to perform such a wide variety of work. For example, the fabrication of an industrial plant may be concurrent with the fabrication of a long span bridge or a multi-storey office building. The rapidity and accuracy with which these structures are fabricated and erected is a tribute to the steel detailers who detail the work and the shop personnel who perform it. An understanding of shop operations will help the beginner to understand the reasons for many conventional practices used in the preparation of shop drawings. A knowledge of the workshop's facilities and equipment will enable the steel detailer to detail pieces that can be fabricated easily and economically.

·· Fabrication shops differ considerably in size and layout. However, most conform to the same general pattern of operation in one or more bays or aisles. The lengths of the bays vary to accommodate required equipment and provide the desired capacity. The bays usually average 18 metres to 24 metres in clear width, and are serviced by overhead travelling gantry cranes spanning the full width of the bay. Jib cranes are often attached to, and swing in an arc about the building columns, for servicing various machines placed beneath them. ,1

'

In large multiple-bay shops, various classes of work are segregated and passed through that bay which is equipped to handle the particular type of work required. In smaller shops, all classifications of work are usually passed through one bay. Repair work, minor fabrication and the storage of bolts and small parts are usually handled in a "lean-to", normally serviced by monorail hoists or fork lift trucks. Structural steel must pass through various operations during the course of its fabrication. The sequence and importance of shop operations vary, depending on the type of fabrication required. This wide variation in operations distinguishes the structural steel fabrication shop from a mass production shop. A typical list of fabrication shop operations follows. A. brief description of the work performed is then given under sub-headings identifying each operation: • • • • • • • • • • •

\1

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material handling and cutting. template making. marking off and setting out. punching and drilling. straightening, bending and rolling. fitting and reaming. assembly (bolting and welding). finishing. quality control. cleaning and painting. shipping. transportation.

A.1

MATERIAL HANDLING AND CUTIING

Most steel is purchased from an established warehouse or steel service centre. It is used for jobs where a customer desires a quicker delivery than is possible with mill order steel and is willing to pay extra for the service. When steel arrives at the plant, it must be identified and checked against the fabricators order list, and segregated for a particular job, or for stock. Some specifications require that steel, as shipped from the rolling mill be marked with the heat number, manufacturer's name, brand or trade mark and size. In addition, when a specified yield stress is required, each plate, shape or lift (a bundle of several pieces) is also marked with the applicable material specification number and colour coded. Mill Test Reports show the result of physical and chemical tests to each heat number and are furnished on request to positively identify the steel. Specifications, generally require identification of high-strength steels during fabrication. These systems of mill identification and control of identification of high-strength steels during fabrication ensure that the material specified for the various members is continuously identified at all times in the fabricators plant. Most material passing through a structural shop is too heavy to lift and move by hand. Overhead cranes, fork lifts and trolleys operating on tracks take the material as received in the shop and deliver it to various machinery. They also handle the material during its movement through the shop and finally deliver the finished fabricated members to the transportation or storage yard.

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Material not cut to length at the mill or distributor must first be sent to the guillotine, cropper, saws or gas-cutting tables. Plates or flat bars under a certain thickness are cut on a guillotine or cropper. Angles are cut on a similar machine capable of shearing both legs with one stroke. Beams, channels and light column shapes are usually cut on a high-speed friction saw or a slower cold saw. A gas torch is used to cut material of a size or thickness beyond the capacity of various machines. It is also used to cut curved or complex forms. This operation is termed oxygen cutting or flame cutting. The cutting torch provides a useful and versatile means of cutting steel. The portable type can be taken to the material, either in the shop, in the yard or on the site. Some gas cutting machines are mounted on power-driven carriages designed to run on small guide tracks. For relatively straight cutting, a guide rail on an adjacent table controls the cutting torches. For more complex cutting, an electronic guide tracer follows a full scale template laid on the adjacent table. Some fabricators use computer numeric controlled (CNC) machines to control the cutting heads and eliminate the need for full size templates.

A.2

TEMPLATE MAKING

A template is a full-size pattern or guide, made of cardboard, wood or metal, used to locate punched or drilled holes, and cuts or bends to be made in the steel. Template making is the first major operation required when a new job starts. Detail drawings should be sent to the shop early enough to ensure an ample supply of templates before actual shop operations begin. The template is the sole guide to many subsequent operations, such as the cutting of plates, fabrication of bent or curved work, and punching or drilling of holes. Each template is marked with the size of required material, number of pieces to be made, the job number, the piece identification mark and the drawing number on which the part is detailed. CNC machines, as described previously in this chapter, have eliminated the need for te_mplates in some operations.

A.3

MARKING OFF

A substantial portion of the steel routed through the shop for fabrication passes through the hands of the marking off crew. Some marking off work is performed without the use of templates. This is true when there is little duplication and marking off is more economical. Construction lines are marked directly on the steel with chalk lines or soapstone markers. A centre punch is then used to locate the centres of holes to be punched and the line along which cutting must be done. The marking off crew checks the plain material for size and straightness. If a piece is bent, or cambered excessively, it must be sent to the straightening machines. Material which is to be marked off from templates is placed on skids with the templates clamped in place. All holes are centre punched and all cuts are marked with a soapstone marker. All centre punch marks and cuts are outlined with painted lines to prevent being overlooked in later operations.

A.4

PUNCHING AND DRILLING

Punching is the most commonly used method of making bolt holes in steel. Normally mild carbon steel up to a thickness of 3 mm greater than the diameter of the fastener can be punched. High-strength steels are somewhat harder and punching may be limited to thinner material. The steel detailer specifies the size of bolt holes to be used. Except in special cases, holes are punched with a diameter 2 mm larger than the nominal diameter of the bolt to be used. This provides clearance for inserting fasteners, with some tolerance for slightly mismatched holes. The type of punch machines vary greatly from single punch to multiple punch in which several holes can be punched simultaneously in angles, channels, beams and plates. The introduction of CNC in some shops permits fully automatic operation. Drilling of structural steel is largely confined to making holes in material thicker than the capacity of the punches, or to meet special job specification requirements. Drilling equipment includes the standard machine shop drill press, radial arm drills, multiple-spindle drills, gantry drills and CNC drilling beam lines. The fixed drill press and the radial arm drill usually drill one hole at a time. For certain classes of work requiring numerous holes, a multi-spindle drill may be used. Machine manufacturers have combined many formerly separate functions into continuously operating lines for the prefabrication of plain material. One such machine moves the material on a conveyor through a series of jaws, and punches or drills all holes. In this equipment the drill stands may consist of one or more spindles, arranged to drill a beam or column flanges and webs simultaneously. One advantage of these highly automated machines is their inherent accuracy. The elimination of dimensional errors in prefabrication greatly simplifies succeeding shop operations, as well as erection.

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A.5

STRAIGHTENING, BENDING AND ROLLING

Material which may have become bent or distorted during transportation and handling, or in the punching/welding operation, must be straightened before further fabrication is attempted. The bend press is generally used for straightening beams, channels, angles and heavy bars. The press is also used to form long radius curves in various structural members. Long plates which are slightly curved, or cambered out of alignment longitudinally, are frequently straightened by the roll straightener. The plates are passed between rolls which exert more pressure on the concave side of the plate than on the convex side. The pressure slightly increases the length of this side and brings the plate back to acceptable tolerances of longitudinal alignment. Misalignments in structural shapes are sometimes corrected by spot or pattern heating. When heat is applied to a · small area of steel, the larger unheated portion of the surrounding material prevents expansion. Upon cooling, the subs.eiquent shrinking produces a shortening of the member, thus pulling it back into alignment. This method is also ·· fr8Quently used to produce camber in rolled beams and horizontal curvature in rolled beams and welded girders. A brake press is used to form angular bends in wide sheets and plates. These machines have throat lengths ranging from approximately 3000 to 6000 mm. Curved plates used in tanks and stacks are formed in a plate roll machine.

A.6 (

FITTING AND REAMING

Before final assembly the component parts of a member must be fitted up, ie. the parts are assembled temporarily with bolts, clamps or tack welds. During this operation, the assembly is squared and checked for overall dimensions. It is then bolted or welded into a finished member. On bolted work, some holes in the connecting material may not always be in perfect alignment and small amounts of reaming may be required to permit·insertion of the fasteners. To assure precise matching of the holes, some specifications require that field connections be reamed to a metal template or that connecting members be shop assembled and reamed while assembled. Either of these operations adds considerably to the cost of fabrication, and is generally specified- only for usually large and important connections, most often encountered in bridge work.

A. 7 . ASSEMBLY ··The strength of the entire structure depends upon the proper use of fastening methods. Where options are permitted by the specifications, a steel detailer must select the most economical fastening method suited to the shop.

f :-. --

A.7.1 Bolting Permanent shop bolting of structural connections is done with hand or power wrenches. Some connections for framing structural steel use 4.6/S grade commercial bolts as fasteners where permitted by specification provisions. These bolts can be tightened by hand with wrenches, turning either bolt or nut until the connected parts of steel are drawn tightly together. However, use of a power wrench operated by compressed air is usually more economical. High strength bolts 8.8/S grade are widely used in connections where loads are heavy. The tightening of high-strength bolts is usually performed by an air operated power impact wrench. Tightening of high-strength bolts must be carefully controlled, to suit the type of connection required ie. 8.8/S, 8.8/TF or 8.8/TB . See Chapter 6.

A.7.2 Welding Welding generators, transformers and automatic welding machines are provided with adjustable controls. These controls are used to obtain welding power characteristics and rates of weld deposit best suited to the type and position of work being welded. The welding current is conducted through insulated cables which are connected, to complete a circuit between the work and the machine, when an electric arc is struck between the electrode and the work to be welded. Long welds of uniform size are usually deposited by automatic welding machines. When a number of identical welded assemblies are to be fabricated, special devices known as jigs are used to locate and clamp the component parts in position. A fixed-type positioner, similar to a jig, permits welding a joint in the most convenient position. However, the fixed positioner restricts the amount of welding that can be performed ASDH/01-1999

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without re-handling a piece. A movable or universal type positioner permits unlimited mechanical positioning of the piece. These devices make welds easily accessible, speed the welding process and permit maximum weld quality at minimum cost. The marking off work for welded fabrication consists chiefly of marking the edges and ends of components for accurate cutting. Drilling or punching of plain material is avoided, and holes for erection bolts are confined to fitting or connection material, when practicable. Sub-assemblies are placed on level skids and tack welded together. This holds the parts in alignment and facilitates completion of the final welding operations. An inspection of each transported unit prior to final shop welding is made to check overall dimensions and the proper location of all connections. This also includes a check of the fit-up of all joints to assure that they can be properly welded.

.•

A.8 . FINISHING

Structural members whose ends must transmit loads by bearing against one another may be finished to a smooth, even surface. Finishing is done by sawing, milling or other suitable means. Several types of sawing machines are available which produce very satisfactory finished cuts. One type of milling machine employs a movable head fitted with one or more highspeed, carbide-tipped rotary cutters. The head moves over a bed which securely holds the work in proper alignment during the finishing operation. The term finished, machine or mill is used on detail drawings to describe any operation that requires the steel to be finished to a smooth, even surface as previously described.

A.9

QUALITY CONTROL

All work which passes through a fabrication shop is subject to inspection by the fabricator's own inspectors. The fabricator should provide a quality control procedure to the extent deemed necessary to assure that all work is performed in accordance with the specification. In addition to checking for compliance with the contract specifications, inspectors should ensure that the job will fit together properly in the field, where correction of errors is very costly. They generally check overall dimensions, locations and dimensions of connections, proper assembly of all fittings and proper installation of fasteners. The inspection of welding requires special attention. In addition to visual inspection, a number of methods have been developed to test the soundness of welds, including magnetic particle inspection, dye penetrate inspection, ultrasonic and radiography inspections. The requirement for these is usually specified by the designer.

A.10 CLEANING AND PAINTING All steelwork which is to be painted is so indicated on the shop drawings (usually in the general notes). Before painting, the steelwork must be thoroughly cleaned of all loose mill scale, loose rust and other foreign matter. The cleaning may be done by hand or power driven wire brushes, by flame de-scaling, by pickling or by sand, shot, or grit blasting. Certain specifications may require a specific type of treatment as in the case of paints requiring a surface free of mill scale. The kind and colour of paint, as well as the method of painting, are also controlled by job specifications. The identification mark is placed on each piece and a check is made to ensure that proper identification is clearly indicated.

A.11 Transportation The loading dock or yard requires a large area serviced by cranes. Here the fabricated members are stored and transported to the field as required. Material destined for distant points is usually transported on railroad cars or trucks. Material for local structures is usually hauled by truck. This requires loading facilities for each type of transport used. Dispatchers must be familiar with railroad and highway regulations. They must have information on maximum permissible loads and bridge clearances. When material is wider, longer or heavier than is normally permitted on streets or highways, special permission must be obtained from the proper local, state or federal authorities.

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Appendix B SAMPLE PROJECT DRAWINGS The following drawings in this Appendix are of an industrial type structure using portal frame construction. Readers should note the progression of these drawings, the type of information they convey and also the particular method of detailing adopted after the marking plans and holding down bolt layout. Another set of detailed drawings are contained in the plastic sleeve enclosed within the Handbook folder which consider a similar - though slightly more complex - structure and alternate detailing method (eg fitting sheets not being used). Both of these sets of drawings were drawn by key steel detailing industry practitioners and are provided for further information for the reader "."hich is beyond that specifically covered in the Handbook.

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1. HORIZONTAL MEMBERS HAVE PIECE-MUM STA11PED ON NORTH CA WEST END AND ON TOP SURFACE. MUXS WlTH ASRERllh ARE STAMPED ON SOUTH OR EAST EllD. 2. cct~5 HAVE PIECE-,..UK STAMPED ON NORTH FACE HEAR BASE CF SHAFT. MARKS WITH ASTERIX•. All€ STAl'l'ED ON SllUTH FACE.

l. VEUICAL BRACING,STAIAS,HANOEAS AND OTHER l~LIHED HEllBERS HAVE PIECE-HAAK STAMPED ON TCP END. HAHS WITll ASTERIXo ARE STAMPED ON BOTTOM END. '· FIN PLATES FDR BEAMS WU BE ON NOllTH 011 WEST SIDE OF BOAM WEB, UNLESS SHOWN OTHUIWISE, ;. EllOCT SUHS TO SO\ITH OR E,\ST SIDE Of (I.EU S. fill PLATES FOR CKANNElS A11E Oli Hl:El UNi.[SS Sf!OWN OTHERWISE. MARKING PLAN ORG No. 1000-0001

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