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AS 5100.3:2017

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AP-G51.3-17

AS 5100.3:2017

Bridge design

Part 3: Foundation and soil-supporting structures

This Australian Standard® was prepared by Committee BD-090, Bridge Design. It was approved on behalf of the Council of Standards Australia on 13 March 2017. This Standard was published on 31 March 2017.

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The following are represented on Committee BD-090:              

Australian Industry Group Australian Steel Institute Austroads Bureau of Steel Manufacturers of Australia Cement and Concrete Association of New Zealand Cement Concrete & Aggregates Australia—Cement Concrete Institute of Australia Consult Australia Engineers Australia New Zealand Heavy Engineering Research Association Rail Industry Safety and Standards Board Steel Construction New Zealand Steel Reinforcement Institute of Australia Sydney Trains

This Standard was issued in draft form for comment as DR AS 5100.3. Standards Australia wishes to acknowledge the participation of the expert individuals that contributed to the development of this Standard through their representation on the Committee and through the public comment period.

Keeping Standards up-to-date Australian Standards® are living documents that reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments that may have been published since the Standard was published. Detailed information about Australian Standards, drafts, amendments and new projects can be found by visiting www.standards.org.au Standards Australia welcomes suggestions for improvements, and encourages readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at [email protected], or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.

AS 5100.3:2017

Australian Standard®

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Bridge design Part 3: Foundation and soil-supporting structures

Originated as HB 77.3—1996. Revised and redesignated as AS 5100.3—2004. Second edition 2017.

COPYRIGHT © Standards Australia Limited All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher, unless otherwise permitted under the Copyright Act 1968. Published by SAI Global Limited under licence from Standards Australia Limited, GPO Box 476, Sydney, NSW 2001, Australia ISBN 978 1 76035 716 0

AS 5100.3:2017

2

PREFACE This Standard was prepared by the Standards Australia Committee BD-090, Bridge Design, to supersede AS 5100.3—2004. This Standard is also designated as AUSTROADS publication AP-G51.3-17. The objective of the AS(AS/NZS) 5100 series is to provide nationally acceptable requirements for— (a)

the design of road, rail, pedestrian and cyclist-path bridges;

(b)

the specific application of concrete, steel and composite steel/concrete construction, which embody principles that may be applied to other materials in association with relevant Standards; and

(c)

the assessment of the load capacity of existing bridges.

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The objective of this Part (AS 5100.3) is to specify the requirements and principles for the design of foundations for bridges and associated soil retaining structures in Australia. The requirements of the AS(AS/NZS) 5100 series are based on the principles of structural mechanics and knowledge of material properties, for both the conceptual and detailed design, to achieve acceptable probabilities that the bridge or associated structure being designed will not become unfit for use during its design life. Whereas earlier editions of the Bridge design were essentially administered by the infrastructure owners and applied to their own inventory, an increasing number of bridges are being built under the design-construct-operate principle and being handed over to the relevant statutory authority after several years of operation. This Standard includes clauses intended to facilitate the specification to the designer of the functional requirements of the owner, to ensure the long-term performance and serviceability of the bridge and associated structure. Significant differences between this Standard and its 2004 version, and earlier versions of Bridge design, are the following: (i)

Definitions and notations Brought into line with current Standards Australia practice.

(ii)

Piling clauses Updated installation.

in

line

with

AS 2159—2009,

Piling—Design

and

(iii) Anchorages Testing requirements revised in line with current practice. (iv)

Foundation design principles In recognition that geotechnical engineering design principles differ from structural engineering design principles, the design procedures have been extensively revised. Designers are required to use geotechnical engineering methods appropriate to the foundation problem at hand, together with appropriate characteristic values and factors, when deriving economical and safe solutions. It is further required that designers apply engineering judgement to the application of sound rational design methods outlined in texts, technical literature and other design codes to supplement the design requirements of this Standard.

(v)

Design procedures Substructures have been classified as either foundations, where most of the loads on the substructure come from the bridge structure and loads on it, or as soil-supporting structures, where most of the applied loads are from earth pressure. Different design procedures are required for each. The loads and resistances for a soil-supporting structure will largely depend on the soil properties, whereas the loads for a foundation will not be as dependent on the soil properties.

3

(vi)

AS 5100.3:2017

Relevant Standard The philosophy used for the design of earth-retaining structures in this Standard differs from that used in AS 4678, Earth-retaining structures, which was prepared by Standards Australia Committee CE-032. It is considered that for bridges and road-related structures, where soil/structure interaction occurs and the loads are predominantly soil-imposed, the design method adopted is more realistic. However, AS 4678 includes criteria that may be used to supplement the design of structures covered by this Standard.

The term ‘shall’ has been used in this Standard for mandatory requirements and the term ‘should’ has been used for desirable (best practice) and/or other measures which, while recommended, are not mandatory. Statements expressed in mandatory terms in Notes to Tables are deemed to be requirements of this Standard.

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The term ‘informative’ has been used in this Standard to define the application of the appendix to which it applies. An ‘informative’ appendix is only for information and guidance.

AS 5100.3:2017

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CONTENTS Page

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SECTION 1 SCOPE AND GENERAL 1.1 SCOPE ......................................................................................................................... 6 1.2 APPLICATION ........................................................................................................... 6 1.3 NORMATIVE REFERENCES .................................................................................... 7 1.4 DEFINITIONS............................................................................................................. 7 1.5 NOTATION ................................................................................................................. 8 1.6 SITE INVESTIGATION.............................................................................................. 8 1.7 MATTERS FOR RESOLUTION BEFORE DESIGN ................................................ 10 SECTION 2 GENERAL DESIGN REQUIREMENTS 2.1 AIM ........................................................................................................................... 12 2.2 DESIGN .................................................................................................................... 12 2.3 DESIGN FOR STRENGTH ....................................................................................... 12 2.4 DESIGN FOR STABILITY ....................................................................................... 15 2.5 DESIGN FOR SERVICEABILITY ........................................................................... 15 2.6 DESIGN FOR STRENGTH, STABILITY AND SERVICEABILITY BY LOAD TESTING A PROTOTYPE ....................................................................................... 15 2.7 DESIGN FOR DURABILITY ................................................................................... 15 2.8 DESIGN FOR OTHER RELEVANT DESIGN REQUIREMENTS........................... 16 SECTION 3 LOADS AND LOAD COMBINATIONS 3.1 GENERAL ................................................................................................................. 17 3.2 LOADS ...................................................................................................................... 17 3.3 LOAD COMBINATIONS FOR STRENGTH AND STABILITY DESIGN .............. 18 3.4 LOAD COMBINATIONS FOR SERVICEABILITY DESIGN ................................. 19 SECTION 4 DURABILITY 4.1 GENERAL ................................................................................................................. 20 4.2 DURABILITY OF TIMBER ..................................................................................... 20 4.3 DURABILITY OF CONCRETE ................................................................................ 20 4.4 DURABILITY OF STEEL ........................................................................................ 20 4.5 DURABILITY OF OTHER MATERIALS ................................................................ 21 SECTION 5 SHALLOW FOOTINGS 5.1 SCOPE OF SECTION ............................................................................................... 22 5.2 LOADS AND LOAD COMBINATIONS .................................................................. 22 5.3 DESIGN REQUIREMENTS...................................................................................... 22 5.4 STRUCTURAL DESIGN AND DETAILING ........................................................... 26 5.5 MATERIALS AND CONSTRUCTION REQUIREMENTS ..................................... 27 SECTION 6 PILED FOUNDATIONS 6.1 SCOPE OF SECTION ............................................................................................... 28 6.2 LOADS AND LOAD COMBINATIONS .................................................................. 28 6.3 DESIGN REQUIREMENTS...................................................................................... 28 6.4 STRUCTURAL DESIGN AND DETAILING ........................................................... 29 6.5 MATERIALS AND CONSTRUCTION REQUIREMENTS ..................................... 31 6.6 TESTING................................................................................................................... 31

5

AS 5100.3:2017

SECTION 7 ANCHORAGES 7.1 GENERAL ................................................................................................................. 32 7.2 LOADS AND LOAD COMBINATIONS .................................................................. 32 7.3 DESIGN REQUIREMENTS...................................................................................... 32 7.4 MATERIALS REQUIREMENTS .............................................................................. 35 7.5 ANCHORAGE INSTALLATION PLAN .................................................................. 35 7.6 ANCHORAGE TESTING ......................................................................................... 35 7.7 MONITORING .......................................................................................................... 37

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SECTION 8 RETAINING WALLS AND ABUTMENTS 8.1 SCOPE OF SECTION ............................................................................................... 38 8.2 LOADS AND LOAD COMBINATIONS .................................................................. 38 8.3 DESIGN REQUIREMENTS...................................................................................... 38 8.4 STRUCTURAL DESIGN AND DETAILING ........................................................... 40 8.5 MATERIALS AND CONSTRUCTION REQUIREMENTS ..................................... 41 8.6 DRAINAGE .............................................................................................................. 41 SECTION 9 BURIED STRUCTURES 9.1 GENERAL ................................................................................................................. 42 9.2 LOADS AND LOAD COMBINATIONS .................................................................. 42 9.3 DESIGN REQUIREMENTS...................................................................................... 42 9.4 STRUCTURAL DESIGN AND DETAILING ........................................................... 44 9.5 MATERIALS AND CONSTRUCTION REQUIREMENTS ..................................... 44 APPENDIX A ON-SITE ASSESSMENT TESTS OF ANCHORAGES ................................ 45 BIBLIOGRAPHY ..................................................................................................................... 53

AS 5100.3:2017

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STANDARDS AUSTRALIA Australian Standard Bridge design Part 3: Foundation and soil-supporting structures SECTI ON

1

SCOPE

AND

GENERAL

1.1 SCOPE This Standard sets out minimum design requirements and procedures for the design in limit states format of foundations and soil-supporting structures for road, rail and pedestrian bridges, culverts not specifically covered by other Standards, and subways of conventional size and form. Foundations include shallow footings, piles and anchorages.

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Soil-supporting structures include retaining walls, abutments and buried structures. The provisions of this Standard also cover the design of foundations for road furniture, such as lighting poles and sign-support structures and noise barriers. The Standard does not cover the design of— (a)

corrugated steel pipes and arches;

(b)

precast reinforced concrete box culverts;

(c)

underground concrete drainage pipes; and

(d)

reinforced soil structures.

NOTES: 1 For reinforced soil structures, refer to relevant authority specifications. 2 The structures covered by this Standard are those specified in Clause 1 of AS 5100.1. This Standard is not applicable to situations outside the scope of AS 5100.1. 3 The requirements for structural design and detailing of concrete and steel are specified in AS 5100.5 and AS/NZS 5100.6; however, a number of specific structural design provisions that result from soil-structure interaction are covered by this Standard. 4 Requirements for corrugated steel pipes and arches are covered by AS/NZS 2041.1. 5 Requirements for fibre-reinforced concrete pipes are covered by AS 4139. 6 Requirements for underground concrete drainage pipes are covered by AS 3725 and AS 4058.

1.2 APPLICATION For the design of foundations for overhead wiring structures for electrified rail lines, the requirements of the relevant authority shall apply. The loads to be applied shall be those specified in AS 5100.2, together with earth pressure loads determined in accordance with this Standard. The general design procedures to be adopted shall be as specified in this Standard. Unless specified otherwise by the relevant authority, the detailed methods and formulae to be used shall be those specified in the relevant Standard for the geotechnical or structural element. Where no Australian Standard exists covering the design of the geotechnical or structural element, rational design methods outlined in texts or other design Standards and technical literature shall be used, as approved by the relevant authority.  Standards Australia

www.standards.org.au

7

AS 5100.3:2017

1.3 NORMATIVE REFERENCES The following are the normative documents referenced in this Standard: NOTE: Documents for informative purposes are listed in the Bibliography.

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AS 1597 1597.2

Precast reinforced concrete box culverts Part 2: Large culverts (from 1500 mm span and up to and including 4200 mm span and 4200 mm height)

1726

Geotechnical site investigations

2159

Piling—Design and installation

5100 5100.1 5100.2 5100.5

Bridge design Part 1: Scope and general principles Part 2: Design loads Part 5: Concrete

AS/NZS 1554 1554.1 1554.3

Structural steel welding Part 1: Welding of steel structures Part 3: Welding of reinforcing steel

5100 5100.6

Bridge design Part 6: Steel and composite construction

1.4 DEFINITIONS For the purpose of this Standard, the definitions below apply. Definitions peculiar to a particular clause are also given in that clause. 1.4.1 Characteristic value In the context of this Standard, the assessed value of a material parameter used in design. 1.4.2 Design values The values of variables entered into the calculations. 1.4.3 Foundation A structural member from which loads imposed predominantly from or via the structural members above, or from loads applied to the structure, are transferred to the ground. 1.4.4 Geotechnical engineer A suitably qualified engineer with relevant geotechnical experience in charge of geotechnical investigation or design, or both. 1.4.5 Reinforced soil walls and structures Earth retaining structures with face within 20° of vertical, which comprise steel or polymer tensile reinforcement embedded in specified fill, together with facing elements, connections and footings. 1.4.6 Soil supporting structure Structures whose main function is to support predominantly soil-imposed loads from vertical or steep-faced soil or earth embankments.

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 Standards Australia

AS 5100.3:2017

8

1.5 NOTATION Symbols used in this Standard are listed below. Unless a contrary intention is given, the following applies: (a)

Where non-dimensional ratios are involved, both the numerator and denominator are expressed in identical units.

(b)

The dimensional units for length, force and stress in all expressions or equations are to be taken as millimetres (mm), Newtons (N) and megapascals (MPa) respectively, unless specifically noted otherwise. Definition

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Symbol Ed

design action effect

Ee

design action effects imposed by the soil

Epr

ultimate passive resistance of the soil in front of the footing

Fem

bending moments, shear forces or axial loads in the foundation induced by lateral soil movements

Fes

compressive and tensile loads in the foundation, structure or its element caused by vertical soil movement

Fnf

negative friction loads on the foundation caused by consolidation of surrounding soil

Hug

ultimate shear resistance at the base of the footing

k

concrete placement factor

Ra

anchorage resistance

Rak

characteristic anchorage strength

Ram

measured anchorage capacity

Rd,g

design geotechnical strength

Rd,s

design structural strength

Ru

ultimate strength

Ru,g

ultimate geotechnical strength

Ru,s

ultimate structural strength

h

depth of soil below nominal ground level in front of retaining wall over which passive earth pressure is to be ignored



strength reduction factor

c

conversion factor

g

geotechnical strength reduction factor

n

importance category reduction factor

s

structural strength reduction factor

1.6 SITE INVESTIGATION 1.6.1 General A site investigation shall be carried out for all structures, to provide the necessary geotechnical information required for the design and construction of foundations and soil-supporting structures.  Standards Australia

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9

AS 5100.3:2017

The investigation shall be carried out under the supervision of a geotechnical engineer, unless specified otherwise by the relevant authority. The site investigations shall be carried out in accordance with AS 1726. Investigations shall be one of the following: (a)

Preliminary investigation An investigation conducted at the feasibility stage in order to assess alternative sites or routes, to prepare conceptual designs, to determine preliminary costings and to define constraints for the design. The extent and coverage of the preliminary investigation shall be as required by the relevant authority. The preliminary investigation may include— (i)

field reconnaissance;

(ii)

topography;

(iii) hydrology; (iv)

geomorphology;

(v)

hydrogeology;

(vi)

examination of neighbouring structures and excavations;

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(viii) previous site investigations and construction experience in the vicinity; (ix)

aerial photographs;

(x)

maps;

(xi)

regional seismicity; or

(xii) any other relevant information. (b)

Design investigation Design investigation shall provide sufficient geotechnical information for the design and construction of the project. The extent and coverage of the design investigation shall include but not be limited to the following: (i)

Nature and size of the structure and its elements, including any special requirements.

(ii)

Conditions with regard to the surroundings of the structure, such as neighbouring structures, traffic, utilities, services, hazardous chemicals and similar conditions.

(iii) Ground conditions with particular regard to geological complexity. (iv)

Groundwater conditions.

(v)

Regional seismicity.

(vi)

Influence of the environment on the structure, such as hydrology, surface water, subsidence and the like.

(vii) Aggressivity of soil and groundwater with respect to materials used in the structure (e.g., acid sulfate soils). (viii) Scour effects. (ix)

Working in the vicinity of electrified rail lines.

(x)

Other relevant factors.

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 Standards Australia

AS 5100.3:2017

10

1.6.2 Ground investigations The number of boreholes or other in situ tests, or both, depends on the proposed structure and the inferred uniformity of the subsoil conditions. Unless specified otherwise by the relevant authority, the minimum number of boreholes shall be as follows: (a)

For bridge foundations Minimum of one per abutment or pier for bridges with bridge width less than 10 m, with an additional borehole for each 10 m of bridge width or part thereof.

(b)

For other structures Investigation as appropriate to the structure and its importance.

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NOTES: 1 This minimum level of investigation would only be satisfactory for sites with relatively uniform subsoil strata and easily defined foundation conditions. 2 Additional boreholes or test locations would be required where bridge approaches involve cuttings or embankments, in order to check that these earthworks would not cause vertical or lateral ground movements, or slope instability, which could adversely affect the bridge or associated structures.

Boreholes, pits or other in situ tests, as required, shall extend through any strata that may influence strength, stability or serviceability, of the foundations or soil-supporting structures during or after construction. The presence of groundwater and its effects shall be investigated. NOTE: Specific groundwater effects may include— (a) the level and fluctuations of the permanent water table; (b) the inflow rates into excavations; (c) effects of dewatering on the water table and on adjacent structures; (d) the presence of, and the pressures associated with, artesian and sub-artesian conditions; and (e) the potential aggressiveness of the groundwater to buried concrete, steel and other materials likely to be affected.

The results of a geotechnical investigation shall be compiled in a geotechnical report verified by a geotechnical engineer. 1.7 MATTERS FOR RESOLUTION BEFORE DESIGN The matters for resolution listed below shall be confirmed as accepted by the relevant authority or owner of a bridge or associated structure before commencing the design process. 1

Design requirements for foundations for overhead wiring structures (see Clause 1.2).

2

Detailed method and formulae to be used for the design of geotechnical or structural elements (see Clause 1.2).

3

Supervision of site investigation (see Clause 1.6).

4

Extent and coverage of preliminary and design investigation (see Clause 1.6).

5

Minimum number of boreholes (see Clause 1.6.2).

6

Selection of the geotechnical strength reduction factors (see Clause 2.3.5).

7

Testing requirements if design by prototype testing (see Clause 2.6).

8

Requirement for consideration of future development (see Clause 2.8).

9

Other durability criteria (see Clause 4.1).

10

Use of treated and untreated timber (see Clause 4.2).

 Standards Australia

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11

AS 5100.3:2017

11

Requirements for prevention of corrosion of reinforcement (see Clause 4.3).

12

Acceptance of rates of corrosion for steel surface (see Clause 4.4).

13

Requirements to minimize corrosion effects on stray currents (see Clause 4.4).

14

Durability requirements of other materials (see Clause 4.5).

15

Design requirements for durability of materials used in shallow foundations (see Clause 5.3.6).

16

Requirements for structural design and detailing for shallow footings (see Clause 5.4).

17

Requirements for materials and construction for shallow foundations (see Clause 5.5).

18

Bridges essential for post-disaster recovery (see Clause 6.3.2).

19

Use of timber piles (see Clause 6.3.2).

20

Requirements for durability of materials used (see Clause 6.3.4).

21

Requirements for structural design and detailing for construction of piles (see Clause 6.4).

22

Requirements for materials and construction for piles (see Clause 6.5.1).

23

Requirements for testing of piles (see Clause 6.6).

24

Design requirements for durability of anchorages and anchorage components (see Clause 7.3.6).

25

Requirements for materials and construction for anchorages (see Clause 7.4).

26

Requirements for method of installation and on-site assessment tests for anchorages (see Clause 7.6.1).

27

Proof load test for anchors (see Clause 7.6.2).

28

Requirements for anchorage suitability tests (see Clause 7.6.3).

29

Requirements for anchorage acceptance tests (see Clause 7.6.4).

30

Requirements for the design of retaining walls and abutments (see Clause 8.1).

31

Acceptance of geotechnical strength reduction factor for retaining walls and abutments (see Clause 8.3.1).

32

Design requirements for durability of retaining walls and abutments (see Clause 8.3.5).

33

Requirements for structural design and detailing for retaining walls and abutments (see Clause 8.4).

34

Requirements for materials and construction for retaining walls and abutments (see Clause 8.5).

35

Approval of drainage system for retaining walls and abutments (see Clause 8.6).

36

Requirements for the design of buried structures (see Clause 9.1).

37

Design requirements for the durability of materials (see Clause 9.3.3).

38

Requirements for structural design and detailing for buried structures (see Clause 9.4).

39

Requirements for materials and construction for buried structures (see Clause 9.5).

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 Standards Australia

AS 5100.3:2017

12

SECTI ON 2 GENERAL DESIGN REQUI REME NTS 2.1 AIM The aim of the design of structures covered by this Standard is to provide a foundation or soil-supporting structure that is durable, stable and has adequate strength while serving its intended function and that also satisfies other relevant requirements, such as robustness, ease of construction, minimum disruption of normal operations during construction and minimal effects on adjacent existing structures accounting for effects of future works. Foundation behaviour shall be compatible with the superstructure so that both remain serviceable and can perform their intended functions. 2.2 DESIGN The design of foundations or soil-supporting structures shall take into account, as appropriate, strength, stability, serviceability, durability and other relevant design requirements in accordance with this Standard.

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2.3 DESIGN FOR STRENGTH 2.3.1 General Foundations and soil-supporting structures shall be designed for both structural and geotechnical strength as follows: (a)

For foundations where the loads are imposed predominantly from or via the structure or loads applied to the structure (e.g., shallow footings, piles and anchorages), the strength shall be determined in accordance with Clause 2.3.2.

(b)

For soil-supporting structures where the loads are predominantly soil-imposed loads (e.g., abutments and buried structures), the strength shall be determined in accordance with Clause 2.3.3.

Where structures act as both foundations and soil-supporting structures (e.g., diaphragm walls supporting bridge abutments), such structures shall be designed to satisfy the requirements of both foundations and soil-supporting structures. 2.3.2 Foundations Foundations shall be designed as follows: (a)

The appropriate loads and other actions shall be determined in accordance with Clause 3.2.

(b)

The loads and action effects shall be factored and combined in accordance with Clause 3.3.2, to determine the design action loads (Ed ) for strength for the foundation and its components for each appropriate load combination. The design geotechnical strength (Rd,g ) shall be obtained by multiplying the appropriate geotechnical strength reduction factor (g ), selected in accordance with Clause 2.3.5, and the ultimate geotechnical strength (Ru,g ), determined in accordance with Sections 5, 6 and 7 as appropriate, using unfactored characteristic values of material parameters, that is— Rd,g = g Ru,g

 Standards Australia

. . . 2.3.2(1)

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AS 5100.3:2017

The foundation components shall be proportioned so that

Rd, g  g Ru, g  Ed (c)

. . . 2.3.2(2)

The design structural strength (Rd,s) shall be obtained by multiplying the appropriate structural strength reduction factor (s) and the ultimate structural strength (Ru,s) for each structural component, determined in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate, that is—

Rd,s = sRu,s

. . . 2.3.2(3)

The structural components of the foundation shall be proportioned so that—

Rd, s  s Ru, s  Ed

. . . 2.3.2(4)

where

Ed = design action effect 2.3.3 Soil-supporting structures

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Soil-supporting structures shall be designed as follows: (a)

The appropriate loads and other actions shall be determined in accordance with Clause 3.2.

(b)

The loads and action effects shall be combined in accordance with Clause 3.3.3, to determine the design loads for strength and stability.

(c)

An appropriate engineering analysis shall be carried out with all loads and load combinations unfactored to determine the design action effects imposed by the soil (Ee) for— (i)

the soil-supporting structure as a whole for geotechnical strength design (e.g., active pressure on a retaining wall, or earth pressure on a buried structure); and

(ii)

each component of the structure for structural strength design (e.g., bending moments or shear forces).

NOTE: As an example, for geotechnical strength design of a retaining wall, the action effects would include the earth pressure arising from dead loading, surcharge loading, pressures arising from compaction, earthquake loading and water pressure. For geotechnical strength design of a buried structure, the action effects would include both vertical and lateral earth pressures arising from the above sources.

(d)

The design geotechnical strength (Rd,g) (e.g., passive resistance on a retaining wall) shall be obtained by multiplying the appropriate geotechnical strength reduction factor ( g ), selected in accordance with Clause 2.3.5, and the ultimate geotechnical strength (Ru,g ), determined in accordance with Sections 8 and 9, as appropriate, using unfactored characteristic values of material parameters, that is—

Rd,g = g Ru,g

. . . 2.3.3(1)

The structure shall be proportioned so that—

Rd,g  g Ru,g  Ed

. . . 2.3.3(2)

where Ed is the design action effect, which shall be equal to 1.0Ee for geotechnical strength design. NOTE: g for soil-supporting structures takes into account the load factors being 1.0.

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AS 5100.3:2017

(e)

14

The design structural strength (Rd,s) shall be obtained by multiplying the appropriate structural strength reduction factor (S) and the design structural strength (Ru,s) for each structural component, determined in accordance with AS 5100.5 or AS/NZS 5100.6, that is—

Rd,s = sRu,s

. . . 2.3.3(3)

Each of the structural components shall be proportioned so that—

s Ru,s  Ed

. . . 2.3.3(4)

where Ed is the design action effect, which shall be equal to 1.5Ee for structural strength design, unless specified otherwise. 2.3.4 Characteristic values

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Characteristic values of the soil and rock parameters shall be selected based on the following considerations: (a)

Geological and geotechnical background information.

(b)

The possible modes of failure.

(c)

Results of laboratory and field measurements, taking into account the accuracy of the test method used.

(d)

A careful assessment of the range of values that may be encountered in the field.

(e)

The ranges of in situ and imposed stresses that may be encountered in the field.

(f)

The potential variability of the parameter values and the sensitivity of the design to these variabilities.

(g)

The extent of the zone of influence governing the soil behaviour, for the limit state being considered.

(h)

The influence of workmanship on artificially placed or improved soils.

(i)

The effects of construction activities on the properties of the in situ soil. NOTES: 1 In general, the characteristic value of geotechnical parameter should be a conservatively assessed value of that parameter. Engineering judgement needs to be exercised in making such an assessment, with geotechnical engineering advice being obtained as required. 2 Many soil parameters are not constants, but depend on factors such as the level of stress or strain, the mode of deformation, drainage conditions, moisture contents and their variations over time. 3 It should be recognized that a low characteristic value of a geotechnical parameter is not always necessarily a conservative value. For example, in cases involving dynamic or earthquake loads, conservatism may require the selection of a high value of a particular parameter. The sensitivity of the calculated result to the relevant parameter should be taken into consideration. 4 Bending moments in buried structures are sensitive to the relative stiffness of the structure and the surrounding soil. The design should consider variation in the stiffness parameters of both the soil and the structure. 5 Except where specifically noted, the term soil includes soil and rock. In many cases, weak weathered rock can be analysed as for soil; however, special techniques may be required for the analysis of strong rock.

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2.3.5 Geotechnical strength reduction factors ( g ) The geotechnical strength reduction factors specified in this Standard shall be used taking into account the following: (a)

Methods used to assess the geotechnical strength.

(b)

Variations in the soil conditions.

(c)

Imperfections in construction.

(d)

Nature of the structure and the mode of failure.

(e)

Importance of the structure and consequences of failure.

(f)

Standards of workmanship and supervision of the construction.

(g)

Load variations and cyclic effects. NOTE: Values of  g for specific cases are set out in Sections 5, 6, 7, 8 and 9.

The geotechnical strength reduction factors selected shall be confirmed and accepted by the relevant authority.

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2.4 DESIGN FOR STABILITY The structure as a whole and each of its elements, including the foundations, shall be designed to prevent instability due to overturning, uplift or sliding, as follows: (a)

Loads determined in accordance with Clause 3.2 shall be subdivided into components tending to cause instability and components tending to resist instability.

(b)

The design action effects (Ed ) shall be calculated from the components of the load tending to cause instability, using the load combinations specified in Clause 3.3.

(c)

The ultimate resistance shall be calculated as set out in Sections 5, 6, 7, 8 and 9. The design resistance shall be computed by multiplying the ultimate resistance by the appropriate strength reduction factor.

(d)

The whole or part of the structure shall be proportioned so that the design action effects are less than or equal to the design resistance.

2.5 DESIGN FOR SERVICEABILITY Foundations and soil-supporting structures shall be designed for serviceability by controlling or limiting settlement, horizontal displacement and cracking. Under the load combinations for serviceability design specified in Clause 3.4, deflections and horizontal displacements shall be limited to ensure that the foundations and the structure remain serviceable over their design lives. 2.6 DESIGN FOR STRENGTH, STABILITY AND SERVICEABILITY BY LOAD TESTING A PROTOTYPE Notwithstanding the requirements of Clauses 2.3, 2.4 and 2.5, foundations or soil-supporting structures may be designed for strength, stability or serviceability by load testing using appropriate test loads as approved by the relevant authority. If this alternative procedure is adopted, the requirements for durability (see Section 4) and other relevant design requirements (see Clause 2.8) shall apply. 2.7 DESIGN FOR DURABILITY Foundations and soil-supporting structures shall be designed for durability in accordance with Section 4.

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2.8 DESIGN FOR OTHER RELEVANT DESIGN REQUIREMENTS Any special design criteria, such as scour, fatigue, flood or collision loading, cyclic loading or liquefaction arising from seismic actions shall be considered. Where relevant, these design criteria shall be taken into account in the design of the foundation or the structure in accordance with the principles of the Standard. When designing new foundations close to existing structures, the effect of the new structure on existing work, during construction and subsequently, shall be considered. The effect of possible future developments on the proposed work after it is completed shall also be considered if required by the relevant authority.

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NOTE: Some of the circumstances specified in this Clause may lead to additional loadings (in the case of floods and collisions), a reduction in the depth of soil-resisting loadings (in the case of scour), or to a reduction in soil strength and stiffness (in the case of scour, flood, fatigue, cyclic loading and liquefaction), or a combination of these effects. In the case of collision loading, the rapid rate of load application may provide a basis to adopt increases in the design strength and stiffness of the soil, but such increases are generally ignored for the purposes of design.

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SECTI ON 3 LOADS AND COMB INATIONS

AS 5100.3:2017

LOAD

3.1 GENERAL The loads and load combinations for strength, stability and serviceability design shall be as specified in Clauses 3.2, 3.3 and 3.4. 3.2 LOADS 3.2.1 General

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The design for ultimate and serviceability limit states shall take into account the appropriate action effects arising from the following: (a)

All loads and other actions specified in AS 5100.2.

(b)

Soil movement resulting from slip, reactive soils, consolidation, heaving and other vertical and lateral earth movements.

(c)

Loads from surcharges.

(d)

Distribution of wheel loads through fill.

(e)

Water pressure loads and seepage forces.

(f)

Increase in loads on buried structures because of differential soil movements.

(g)

Compaction pressures.

(h)

Displacement pressures from piling.

(i)

Any additional loads and actions that may be applied.

3.2.2 Loads induced by soil movement Allowance shall be made for loads induced by soil movement as follows: (a)

Where foundations are situated in soil undergoing settlement, allowance shall be made for loads resulting from negative friction on the foundation (Fnf).

(b)

Where foundations are situated in expansive soils, such as reactive clays or those subject to frost action, allowance shall be made for the compressive and tensile loads (Fes) which may develop in the foundation, structure or its elements.

(c)

Where foundations are subject to lateral soil movements, allowance shall be made for bending moments, shear forces and axial loads (Fem) induced by such movements.

(d)

Where heave may arise because of unloading of the ground as a result of excavation, allowance shall be made for the bending moments, shear forces and axial loads (Fem) induced by the resulting ground movements.

NOTE: Consideration should be given to each of the following conditions when earth pressure loads on retaining structures are being determined: (a) Configuration, nature and drainage properties of the backfill material. (b) Displacement characteristics of the wall. (c) Interface conditions between the wall and the backfill. (d) Method of compaction of the backfill material. (e) Sequences of excavation and placement of anchorages and struts.

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In spill-through abutments, to take into account the possible arching of fill between columns, one of the following procedures shall be adopted: (i)

A detailed ground-structure interaction analysis shall be carried out to determine the earth pressures acting on the columns.

(ii)

In the absence of a detailed analysis, no reduction of earth pressure loading shall be made, to allow for a space between columns if that space is less than twice the width across the back of the columns. For greater spacings, friction on the sides of the columns or counterforts shall be considered and the earth pressure loading on each column shall be taken on an equivalent width not less than twice the actual width across the back of the columns.

3.2.3 Construction loads Loads and actions that arise from construction activities shall be evaluated, and those that affect the requirements for strength, stability or serviceability shall be taken into account. 3.2.4 Water pressure

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The loads applied by hydrostatic pressure of water or groundwater seepage forces, or both, shall be taken into account in the design of foundations and soil-supporting structures. The effects of buoyancy on the structural components and on soil shall be included. 3.3 LOAD COMBINATIONS FOR STRENGTH AND STABILITY DESIGN 3.3.1 General The load combinations for strength and stability design shall be as specified in Clauses 3.3.2 and 3.3.3. 3.3.2 Foundations For foundations where the loads are imposed predominantly from the structure or from loads applied to the structure, the load combinations shall be as follows: (a)

The design loads for a foundation shall be the combination of factored loads that produces the most adverse effect on the foundation in accordance with AS 5100.2.

(b)

If there are loads caused by soil movements (see Clause 3.2.1), the loads shall be considered as permanent effects and shall be factored and combined with the other load combinations specified in AS 5100.2 as follows: (i)

For structural strength and stability design, the loads caused by soil movements shall be factored as follows: (A) 1.2 Fnf—For negative friction loads caused by consolidation of the surrounding soil. (B) 1.5 Fes—For compressive and tensile loads caused by vertical soil movements other than consolidation of the surrounding soil. (C) 1.5 Fem—For bending moments, shear forces and axial loads induced by lateral soil movements and heave.

(ii)

For geotechnical strength design, the possibility of soil movements altering the ultimate geotechnical strength shall be considered. NOTE: Usually, soil movements have greater effect on serviceability than on ultimate geotechnical strength of foundations.

Where other additional loads and actions are to be applied and no load factor is given in AS 5100.2 for these loads and actions, a load factor not less than 1.5 shall be adopted for both structural and geotechnical design.

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AS 5100.3:2017

3.3.3 Soil-supporting structures For soil-supporting structures where the loads are imposed predominantly from the soil, the design loads and other actions for strength and stability design of a soil-supporting structure shall be the combination of loads that produces the most adverse effect on the structure in accordance with AS 5100.2. The loads shall be combined using a load factor of 1.0 for each of the loads. 3.4 LOAD COMBINATIONS FOR SERVICEABILITY DESIGN The design loads and other actions for serviceability design of foundations and soil-supporting structures shall be taken from the appropriate combination of factored loads in accordance with AS 5100.2. The design loads shall include loads resulting from soil movements and other additional loads specified in Clause 8.2, where appropriate, using a load factor of 1.0 for each of these loads.

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NOTE: Soil movements may affect the structure and cause movements that may adversely affect the serviceability of the structure.

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SECTI ON

4

DURABILITY

4.1 GENERAL The objective of the design of the structure with respect to durability shall be— (a)

to achieve, with appropriate maintenance, the specified design life; and

(b)

that all the specified design criteria continue to be satisfied throughout the design life.

Consideration shall be given to the possibility of deterioration of structural components of foundations and soil-supporting structures as a result of aggressive substances in soils or rocks, in groundwater, sea water and water in streams. Account shall also be taken of the abrading effects of waterborne sands and gravels. Consideration shall be given to preventing damaging galvanic corrosion of the structure by eliminating electrochemical contact between dissimilar metals. NOTE: Additional measures, together with appropriate detailing, may be needed to achieve the design life in aggressive environments.

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The requirements of this Clause shall apply to all foundations and soil-supporting structures, except for piles, which shall be as specified in Clause 6.3.4. In addition, other specific durability criteria may apply, as required by the relevant authority. 4.2 DURABILITY OF TIMBER Untreated timber shall not be used as permanent components of foundations or soil-supporting structures unless permitted by the relevant authority. Any untreated timber shall be located below the permanent groundwater level. Where borers exist, untreated timber shall not be used in marine conditions. Where permitted by the relevant authority, appropriately treated timber of durable species may be used as permanent components of foundations or soil-supporting structures, provided its use is limited, having due regard to consequences of failure and replacement and the degree to which the treatment is effective over the entire cross-section. 4.3 DURABILITY OF CONCRETE The requirements for design for durability of concrete components of foundations and soil-supporting structures given in AS 5100.5 shall apply. For buried concrete structures where stray currents are likely to be present (e.g., adjacent to electrified rail lines), action shall be taken, as required by the relevant authority, to prevent corrosion of the reinforcement. 4.4 DURABILITY OF STEEL Unless more site-specific information is available and unless specified otherwise by the relevant authority, the following rates of corrosion for unprotected steel surfaces shall be used for design purposes: (a)

1.5 mm total for the life of the structure for each face in contact with soil, above and below groundwater, provided the soil is undisturbed or comprises compacted, well-graded, chemically neutral, structural fill.

(b)

0.025 mm per year for each face in contact with open-graded or rubble fill, or sands and gravels that have moving groundwater.

(c)

0.05 mm per year for each face exposed to fresh water and not in contact with soil.

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(d)

AS 5100.3:2017

0.08 mm per year for each face exposed to sea water, except in the splash zone where twice this rate shall be used.

NOTES: 1 The presence of high concentrations of chloride ions, oxygen and sulfate-reducing bacteria are significant in determining the level of corrosion, including pitting corrosion, to steel surfaces. 2 Buried or immersed steel surfaces may be protected by galvanizing or coating with various materials, including bitumen, flake-filled polyesters, epoxy mastics and polyethylene in accordance with AS 4312. Detailing and preparation of the steel for receipt of the coating should be in accordance with AS 4312 and the additional requirements of the coating manufacturer. The expected life of the galvanizing or coatings should be taken into account in the design. 3 The expected life of coatings should be estimated in accordance with AS 4312 and taken into account in the design. 4 Estimates of the corrosion rates for galvanized coatings can also be found in AS 2041.1.

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For steel surfaces exposed to the atmosphere, the rate of corrosion will depend on the type of protective coating, level of stress, structural details, the extent of routine maintenance and atmospheric conditions. The rate of corrosion to be adopted shall be as required by the relevant authority. For buried steel structures where stray currents are likely to be present (e.g., adjacent to electrified rail lines), action as required by the relevant authority shall be taken to minimize corrosion. 4.5 DURABILITY OF OTHER MATERIALS Where foundations or soil-supporting structures are to be constructed from materials other than those covered specifically by this Standard, reference shall be made to other appropriate Standards and current technical literature for material-specific information on durability. Where possible, durability of such materials shall be assessed using testing appropriate to the particular situation. The durability of other materials shall be as required by the relevant authority.

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SECTI ON

5

SHALLOW

FOOTINGS

5.1 SCOPE OF SECTION This Section applies to all types of shallow footings, such as pad, strip and raft footings for structures and retaining walls. For the purpose of this Standard, a shallow footing is one that is founded at shallow depth and where the contribution of the strength of the ground above the footing level does not influence the bearing resistance significantly. 5.2 LOADS AND LOAD COMBINATIONS Shallow footings shall be designed for the loads and other actions set out in Clause 3.2. The load combinations for strength, stability and serviceability shall be as specified in Clauses 3.3.2 and 3.4. 5.3 DESIGN REQUIREMENTS

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5.3.1 General The magnitude and disposition of the structural loads and actions, and the bearing resistance of the ground, shall be considered when selecting the appropriate type of shallow footing. The footing shall be designed to satisfy the strength design requirements set out in Clause 2.3.2 and the serviceability design requirements set out in Clause 2.5. 5.3.2 Footing depth and size When determining the footing depth, the following shall be considered: (a)

The depth of an adequate bearing stratum.

(b)

The effects of scour.

(c)

In the case of clay soils, the depth of appreciable ground movement caused by shrinkage and swelling due to moisture changes resulting from seasonal variations or trees and shrubs.

(d)

The depth to which frost heave is likely to cause appreciable ground movements.

(e)

Subsequent nearby construction work such as trenches for services.

(f)

Possible ground movements.

(g)

The level of the groundwater table and the problems that may occur if excavation for the foundation is required below this level.

NOTES: 1 Consideration should be given to the effects of stormwater infiltration and leaking utilities. 2 When determining the footing width, consideration should be given to issues related to practical excavation constraints, setting-out tolerances, working space requirements and the dimensions of the substructure supported by the footing.

5.3.3 Design for geotechnical strength 5.3.3.1 General Ultimate limit states corresponding to a mechanism in the ground or rupture of a critical section of the structure because of ground movements shall be evaluated using the ultimate limit state actions and loads, and the ultimate resistance factored by an appropriate strength reduction factor.

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AS 5100.3:2017

5.3.3.2 Overall stability Consideration shall be given to the possibility of failure resulting from loss of overall stability. The design resistance for stability failure of the ground mass shall be not less than the design strength effect of any possible modes of failure. NOTE: Situations in which overall stability may be particularly important include— (a) footings near or on an inclined site, a natural slope or an embankment; (b) footings near an excavation or a retaining structure; (c) footings near a river, canal, lake, reservoir or the sea shore; and (d) footings near mine workings or buried structures.

5.3.3.3 Ultimate bearing failure Footings subjected to vertical or inclined loads or overturning moments shall be proportioned such that the design bearing capacity is greater than or equal to the design action effect (Ed ), that is—

g Ru,g  Ed

. . . 5.3.3.3

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where

g

= geotechnical strength reduction factor

Ru,g = ultimate geotechnical strength (bearing capacity) of the footing In assessing Ed , allowance shall be made for the weight of the footing and any backfill material on the footing. The value of Ru,g shall be established by using the results of field or laboratory testing of the ground. Allowance shall be made for the effects of the following: (a)

Variations in the level of the groundwater table and rapid draw-down.

(b)

Any weak or soft zones in the soil or rock below the founding level.

(c)

Unfavourable bedding or jointing of rock strata, especially in sloping ground.

(d)

Possible influence of time effects and transient, repeated or vibratory loads on the soil shear strength.

(e)

Load eccentricity and inclination. In assessing the ultimate geotechnical strength (Ru,g ) of footings subjected to eccentric loads, allowance shall be made for the possibility of very high edge stresses and a reduced effective contact area between the footing and the ground as a result of load eccentricity.

(f)

Presence of sloping ground or nearby excavations.

NOTE: The ultimate bearing capacity of a footing may be estimated analytically by using soil shear strengths measured in appropriate laboratory or field tests, or by using empirical or quasi-analytical relationships developed from the results of in situ tests such as the standard penetration test, the static cone penetration test, the plate loading test, the vane shear test or the pressure meter test.

The geotechnical strength reduction factor ( g ) shall be selected in accordance with Clause 2.3.5, and Tables 5.3.3.3(A) and 5.3.3.3(B).

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TABLE 5.3.3.3(A) RANGE OF VALUES OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR SHALLOW FOOTINGS Method of assessment of ultimate geotechnical strength

Range of values of g

Analysis using geotechnical parameters based on appropriate advanced in situ tests

0.50–0.65

Analysis using geotechnical parameters from appropriate advanced laboratory tests

0.45–0.60

Analysis using cone penetration test (CPT)

0.40–0.50

Analysis using standard penetration test (SPT)

0.35–0.40

TABLE 5.3.3.3(B) ASSESSMENT OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR SHALLOW FOOTINGS

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Lower end of range

Upper end of range

Limited site investigation

Comprehensive site investigation

Simple methods of calculation

More sophisticated design method

Limited construction control

Rigorous construction control

Severe consequences of failure

Less severe consequences of failure

Significant cyclic loading

Mainly static loading

Foundations for permanent structures

Foundations for temporary structures

Use of published correlations for design parameters

Use of site-specific correlations for design parameters

5.3.3.4 Failure by sliding Footings subjected to horizontal loads shall be proportioned such that the design action effect (Ed ) shall satisfy the following:

g H ug  g Epr  Ed

. . . 5.3.3.4

where

Hug = ultimate shear resistance at the base of the footing Epr = ultimate passive resistance of the soil in front of the footing

g

= geotechnical strength reduction factor, which shall be selected in accordance with Clause 2.3.5, and Tables 5.3.3.3(A) and 5.3.3.3(B) NOTE: The values of both H ug g and Epr g should be related to the scale of movement anticipated under the limit state being considered. For large movements associated with ultimate limit states, the possible relevance of post-peak softening behaviour should be considered.

For foundations on clay soils bearing within the zone of seasonal movements, the possibility that the clay could shrink away from the vertical faces of foundations shall be considered. The possibility that the soil in front of the foundation could be removed by erosion or human activity shall be considered.

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AS 5100.3:2017

5.3.4 Design for structural strength 5.3.4.1 General The design structural strength (Rd,s) of the footing shall satisfy the following:

Rd,s = sRu,s  Ed

. . . 5.3.4.1

where

s

= structural strength reduction factor

Ru,s = ultimate structural strength Ed = design action effect

s shall be obtained from AS 5100.5 or AS/NZS 5100.6, as appropriate. When calculating Ru,s for strip footings or raft footings, consideration shall be given to the distribution of soil pressure at the base of the footing. 5.3.4.2 Structural failure as a result of footing movement

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Differential vertical and horizontal displacements of a footing or between footings under the serviceability limit state design actions and ground deformation parameters shall be considered. The footing shall be designed such that these displacements do not lead to an ultimate limit state occurring in the supported structure. 5.3.5 Design for serviceability limit states 5.3.5.1 General Consideration shall be given, as appropriate, to the following: (a)

The displacement of a single footing.

(b)

Displacements and differential displacements of footing groups, footing beams or rafts.

(c)

Vibrations arising from repetitive, vibratory or dynamic loads.

Footing displacements shall be calculated using the serviceability loads and actions. Calculated footing displacements shall satisfy the following: (i)

The displacement shall be not greater than the serviceability limit displacement.

(ii)

The differential displacement shall be not greater than the serviceability limit value.

The serviceability limit values of displacement and differential displacement shall be selected such that they do not result in detrimental effects on the structure being supported. In estimating the displacements, consideration shall be given to the following components of displacement: (A)

Immediate displacement.

(B)

Time-dependent displacements caused by soil consolidation.

(C)

Long-term soil creep displacements.

Any possible additional settlement caused by self-compaction of the soil shall also be assessed. The differential settlements and relative rotations shall be assessed, taking account of both the distribution of loads and the possible variability of the ground. NOTE: Differential settlements calculated without taking account of the stiffness of the structure tend to be over-predictions. An analysis of ground-structure interaction may be used to justify reduced computed values of differential settlements.

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Characteristic values of soil deformation design parameters for use in analysis of footing displacements for the serviceability limit state shall be assessed on the basis of appropriate laboratory tests or field tests, or by evaluating the behaviour of neighbouring similar structures. A geotechnical reduction factor need not be applied to the parameters so assessed. NOTES: 1 In general, the characteristic value of a geotechnical parameter should be a conservatively assessed value of that parameter. Engineering judgement needs to be exercised in making such an assessment. 2 Footing displacements may be estimated from various methods, including— (a) analysis using elastic theory, using appropriate parameters for immediate and long-term displacements; (b) analysis using consolidation theory, which is useful for clay soils where there is a relatively large time-dependent displacement component due to consolidation; (c) analysis using appropriate soil constitutive models, usually via finite element analysis; and (d) analysis using results from in situ tests, which may include both analytical techniques and empirical methods (applied mainly to sandy soils).

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5.3.5.2 Tilting The calculated tilt of the footing shall be not greater than the serviceability limit value for proper functioning of the supported structure. In the case of footings subject to loads with large eccentricities, measures shall be adopted to avoid ‘doming’ of the ground surface beneath the footing, which may cause rocking of the footing. NOTE: Situations that may cause significant tilting include— (a) eccentric loads; (b) inclined loads; (c) non-uniform soil conditions; and (d) overturning moments.

5.3.6 Design for durability Durability requirements shall be considered as set out in Section 4. Where materials other than concrete and steel are to be used for the construction of the shallow footing, the requirements for durability in the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used in the shallow foundation, the requirements of the relevant authority shall apply. 5.4 STRUCTURAL DESIGN AND DETAILING Structural design and detailing for shallow footings built of concrete and steel shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements of the relevant Standard for that material shall apply to the structural design and detailing of the structure, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the structure, the requirements of the relevant authority shall apply.

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AS 5100.3:2017

5.5 MATERIALS AND CONSTRUCTION REQUIREMENTS Materials and construction requirements for shallow foundations built of concrete and steel shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements of the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority.

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Where no Standard applies to the materials used for the construction of the structure, the requirements of the relevant authority shall apply.

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SECTI ON

6

PILED

FOUNDATIONS

6.1 SCOPE OF SECTION This Section sets out requirements for the design, construction and testing of piled foundations. The provisions apply to axially and transversely loaded displacement and non-displacement piles installed by driving, jacking, screwing or excavating with or without grouting. 6.2 LOADS AND LOAD COMBINATIONS Loads and load combinations for pile design shall be in accordance with AS 2159, except where specified otherwise in Section 3. 6.3 DESIGN REQUIREMENTS 6.3.1 General Pile design requirements and procedures shall be in accordance with AS 2159, except where specified otherwise in Section 2 and Clauses 6.3.2 to 6.3.4.

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6.3.2 Design for strength The geotechnical design of piles and geotechnical strength reduction factors shall be in accordance with AS 2159. Structural design for steel and concrete piles shall be in accordance with AS 2159, except where specified otherwise in AS 5100.5 and AS/NZS 5100.6. For bridges essential to post disaster recovery, as determined by the relevant authority, the geotechnical and structural strength factors shall both be multiplied by 0.90. The concrete placement factor (k) shall be 0.90 times that given in AS 2159 for all structures. NOTE: For an explanation of the concrete placement factor (k), see AS 2159.

Where the use of timber piles is permitted by the relevant authority, timber piles shall be designed in accordance with AS 2159. 6.3.3 Design for serviceability For the serviceability design of piled foundations, the provisions of Clause 2.5 shall apply. In estimating the settlement and horizontal displacements, account shall be taken of the stiffness of the ground and structural elements, and of the sequence of construction. The permissible displacements for the piled foundations shall be established, taking into account the tolerance to deformation of the supported structure and services. 6.3.4 Design for durability Design for durability shall be in accordance with AS 2159, except where specified otherwise in AS 5100.5 and AS/NZS 5100.6. Where materials other than concrete and steel are to be used, the requirements for durability in the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used, the requirements of the relevant authority shall apply. Slip layer coatings applied to piling shall be as approved by the relevant authority.

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AS 5100.3:2017

6.4 STRUCTURAL DESIGN AND DETAILING 6.4.1 General Structural design and detailing for steel and concrete piles shall be in accordance with AS 2159, except where specified otherwise in AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for construction of the pile, the requirements of the relevant Standard for that material shall apply to the structural design and detailing of the pile, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the pile, the requirements of the relevant authority shall apply.

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Piles shall be designed as structural columns with the degree of end fixity and lateral support appropriate to the surrounding soil conditions and the behaviour of the structure. The effects of scour in removing lateral support shall be considered. Unless specified otherwise by the relevant authority, piles subjected to lateral loads or bending moment shall be designed to provide a design resistance greater than or equal to the maximum serviceability and ultimate design action effects for a distance at least 2 m below the point where lateral support commences. Piles shall be supplied and delivered in maximum practical lengths to minimize the number of splices required to be carried out on site. In addition to considerations relevant to the design of piles as structural members, the design of specific types of piles shall take into account the requirements set out in Clause 6.4.2, as appropriate. 6.4.2 Design details relevant to specific types of piles 6.4.2.1 Precast reinforced concrete piles For precast reinforced concrete piles, the following shall apply: (a)

Size and shape The cross-sectional area shall be not less than 90 000 mm2 except that where the pile is in salt water, it shall be not less than 140 000 mm2 . Any square corners shall have a 25 mm chamfer. Full length tapered piles shall not be used.

(b)

Driving straps The head of a reinforced concrete pile shall be reinforced with a steel strap a minimum of 6 mm thick and 75 mm wide, cast with the pile to minimize spalling under hard driving conditions.

(c)

Reinforcement Longitudinal reinforcement, consisting of not less than four bars spaced uniformly around the perimeter of the pile, shall be provided in all cases for the full length of the pile. Joints in longitudinal reinforcement shall be avoided if possible. Where required, such joints shall be made by butt welding in accordance with AS/NZS 1554.3 or by the use of mechanical splices in accordance with AS 5100.5. The full length of the longitudinal reinforcement shall be enclosed with stirrups or helical reinforcement of not less than 5 mm diameter. The volume of the stirrups or helical reinforcement shall be not less than 0.2% of the gross volume of the pile, with a spacing or pitch of not more than half the average least width, or diameter, of the pile. For a distance from each end of the pile of not less than two times the average least pile width, or diameter, the volume of the stirrups or helical reinforcement shall be not less than 0.4% of the volume of that part of the pile. For the spacing of the stirrups or helical reinforcement, the transition from the close spacing at the ends of the pile to the larger spacing shall be not less than two times the average least pile width.

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(d)

Mechanical joints Mechanical joints shall only be used with the approval of the relevant authority. Precast pile lengths mechanically joined shall be not less than 3 m and not more than 20 m long. The mechanical joints shall be designed so that they provide a permanent connection between the pile lengths. The strength of the joint shall be not less than that of the lengths of pile being joined. Durability of mechanical joints shall comply with Section 4.

(e)

Driving shoes Driving shoes may be either iron castings or made up from welded steel plate. Steel plate shall be not less than 10 mm thick. Welding shall be GP in accordance with AS 1554.1. For hard driving, the driving shoe may incorporate a rock point.

6.4.2.2 Prestressed concrete piles

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For prestressed concrete piles, the following shall apply: (a)

Concrete strength The concrete shall have a 28 days compressive strength of not less than 50 MPa.

(b)

Size and shape The provisions of Clause 6.4.2.1(a) shall apply. Piles with a diameter or average least width less than 450 mm shall be solid. Larger diameters or average least widths may be hollow.

(c)

Prestress and reinforcement Prestressing tendons shall be provided, and shall be spaced uniformly around the perimeter of the pile. The minimum residual compressive stress shall be 7 MPa. Non-prestressed longitudinal reinforcement shall be provided as required for driving, splicing and anchorage to pile caps. Helical reinforcement or stirrups shall be provided as set out in Clause 6.4.2.1(c) except that for hollow piles the volume of helical reinforcement or stirrups in the body of the pile shall be not less than 0.3% of the gross pile volume, and for solid piles not less than 0.2%.

(d)

Mechanical joints The provisions of Clause 6.4.2.1(d) shall apply.

6.4.2.3 Cast-in-place concrete piles For cast-in-place concrete piles, the following shall apply: (a)

Reinforcement Where the pile is reinforced, longitudinal reinforcement shall be placed equally spaced around the perimeter of the pile and shall extend the full depth of the pile. The clear spacing between longitudinal bars shall be not less than 75 mm, including bars at lapped splices. Stirrups or helical reinforcement shall be in accordance with AS 5100.5.

(b)

Casing Steel casings provided for ground support or inspection purposes shall have a minimum thickness of 8 mm. Welding of casings shall be in accordance with AS/NZS 1554.1.

6.4.2.4 Steel piles Steel piles and other steel bridge foundation support systems shall have a minimum thickness of 10 mm at the end of the design life after taking into account corrosion. Welding of steel piles shall be in accordance with AS/NZS 1554.1.

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6.5 MATERIALS AND CONSTRUCTION REQUIREMENTS 6.5.1 General Piles shall be constructed in accordance with AS 2159, except where specified otherwise in AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for construction of the pile, the requirements of the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the pile, the requirements of the relevant authority shall apply. 6.5.2 Spacing, edge distance and embedment of piles For friction piles, the spacing centre-to-centre shall be not less than 2.5 times the diameter or nominal size of the pile. For piles deriving their resistance mainly from end-bearing, the spacing centre-to-centre shall be not less than twice the size of the pile. For piles with rakes or enlarged bases, increased spacing may be required to suit the geometry and clearances.

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The distance from the outside of any pile in a pile group to the edge of a concrete pile cap shall be a minimum of 100 mm after taking into account construction tolerances. The embedment of the concrete of a concrete pile into a concrete pile cap shall be a minimum of 50 mm. Contiguous and secant piles do not need to comply with the spacing requirements of this Clause. 6.6 TESTING Static, dynamic and integrity testing of piles shall be in accordance with AS 2159, unless specified otherwise by the relevant authority.

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SECTI ON

7

ANCHORAGES

7.1 GENERAL This Section sets out requirements for post-tensioned soil and rock ground anchors used to restrain a structure by transmitting a tensile force to a loadbearing formation of soil or rock. NOTES: 1 The design principles of this Clause may also be applied to non-prestressed ties and anchors (e.g., deadman anchors, soil nails, sheet piles, raked piles). 2 Anchorages may be employed as temporary or permanent elements of a structure.

7.2 LOADS AND LOAD COMBINATIONS Anchorages shall be designed for the loads and other actions set out in Clause 3.2. The load combinations for strength, stability and serviceability shall be as specified in Clauses 3.3 and 3.4. 7.3 DESIGN REQUIREMENTS

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7.3.1 General Anchorage design shall take into account all foreseeable circumstances during the design life of the anchorage. The corrosion and creep of the permanent anchorages shall be considered. NOTE: Anchorage systems for which successful long-term experience has been documented with respect to performance and durability should be used.

7.3.2 Site investigation Site investigations shall include the areas where development of the anchorage forces is expected. 7.3.3 Design for strength For the geotechnical and structural strength design of anchorages, the provisions of Clause 2.3 shall apply. For ground anchors, the design geotechnical strength (Rd,g )and the design structural strength (Rd,s) shall be calculated as the appropriate ultimate strength (Ru ) multiplied by an importance category reduction factor (n ) given in Table 7.3.3(A) and the appropriate reduction factor (s) or (g ). The structural strength reduction factor (s) shall be obtained from AS 5100.5 or AS/NZS 5100.6, as appropriate. The geotechnical strength reduction factor ( g ) shall be selected in accordance with Clause 2.3.4, and Tables 7.3.3(B) and 7.3.3(C). To check anchorage strength limit states, three failure mechanisms shall be analysed as follows: (a)

The failure of the tendon or anchor head in terms of the material strength or failure of bonding at internal interfaces.

(b)

The failure of the anchorage at the tendon-grout or grout-ground interfaces.

(c)

The overall stability failure of the structure, including the anchorages.

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AS 5100.3:2017

TABLE 7.3.3(A) IMPORTANCE CATEGORY REDUCTION FACTOR ( n ) Importance category reduction factor ( n )

Anchor category 1

2

3

Temporary anchors where the service life is less than six months and failure would have few serious consequences and would not endanger public safety (for example, short-term pile test loading using anchors as a reaction system)

1.0

Temporary anchors with a service life of up to two years where, although the consequences of local failure are quite serious, there is no danger to public safety without adequate warning (for example, retaining wall tie backs)

0.93

Any permanent anchors and also temporary anchors where the consequences of failure are serious (for example, temporary anchors for main cables of a suspension bridge), or as a reaction for lifting structural members

0.7

TABLE 7.3.3(B)

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RANGE OF VALUES OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR ANCHORAGES Method of assessment of ultimate geotechnical strength

Range of values of g Permanent structures

Temporary structures

Analysis using the results of site-specific anchorage pull-out tests

0.55

0.60–0.70

Analysis using the results of anchorage pull-out tests in similar ground conditions

0.55

0.55–0.65

Analysis using geotechnical parameters based on appropriate advanced in situ tests

0.5–0.55

0.50–0.65

Analysis using geotechnical parameters from appropriate advanced laboratory tests

0.45–0.55

0.45–0.60

Analysis using cone penetration test (CPT)

0.40–0.50

0.40–0.50

Analysis using standard penetration test (SPT)

0.35–0.40

0.35–0.40

TABLE 7.3.3(C) ASSESSMENT OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR ANCHORAGES Lower end of range

Upper end of range

Limited site investigation

Comprehensive site investigation

Simple methods of calculation

More sophisticated design method

Limited construction control

Rigorous construction control

Severe consequences of failure

Less severe consequences of failure

Significant cyclic loading

Mainly static loading

Use of published correlations for design parameters

Use of site-specific correlations for design parameters

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7.3.4 Design for other relevant factors

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During the design of anchorages, the following additional factors shall be considered: (a)

Creep movement of soil.

(b)

Level of groundwater table and possibility of changes in that level during the design life of the structure.

(c)

Provision for drainage.

(d)

Depths of anchorages relative to global stability of the structure.

(e)

Rigidity of the structure being supported.

(f)

Possibility of movement of the structure.

(g)

Group effects.

(h)

In the case of anchorages in soil, the behaviour of the soil due to the anchor loads.

(i)

In the case of anchorages in rock, anisotropy, inhomogeneity, fracturing and discontinuities in the rock.

(j)

Method of installation.

(k)

Geometry of the anchorage.

(l)

Uplift resistance of soil or rock mass.

(m)

Tendon design.

(n)

Rock to grout bond and grout to tendon bond (grouted anchors).

(o)

Soil to tendon bond for soil nails or soil reinforcement.

(p)

Strength of mechanical anchorage for mechanically secured anchors.

(q)

Non-uniform stress distribution, particularly the potential for ‘unzipping’ failure for anchors with long bond lengths.

7.3.5 Design for serviceability For the serviceability design of anchorages, the provisions of Clause 2.5 shall apply. Consideration shall be given, as appropriate, to the following: (a)

Loss of anchor force by excessive displacement of the anchor head.

(b)

Loss of anchor force as a result of creep and relaxation.

(c)

Failure or excessive deformation of the structure due to anchor forces.

7.3.6 Design for durability Anchorages and all anchorage components shall be designed to meet the requirements of Clause 9. The design life shall be in accordance with AS 5100.1. Protection against corrosion shall be provided for all permanent anchorages as required for compliance with Section 4. Where materials other than concrete and steel are to be used for the construction of the anchorage, the requirements for durability in the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the anchorage, the requirements of the relevant authority shall apply.

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7.4 MATERIALS REQUIREMENTS Materials for anchorages shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for the anchorage, the requirements of the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used in the anchorage, the requirements of the relevant authority shall apply. 7.5 ANCHORAGE INSTALLATION PLAN An anchorage installation plan shall be prepared as part of the technical construction specification for the anchorage system to be used.

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An anchorage installation plan shall contain the following information, as appropriate: (a)

Anchorage type.

(b)

Number of anchorages.

(c)

Location and orientation of each anchorage and tolerances in position.

(d)

Anchorage length.

(e)

Installation sequence for the anchorages.

(f)

For grouted anchorages, the grout material specification, pressure, grouted volume, grouted length and grouting time.

(g)

Required serviceability load for each anchorage.

(h)

Method of corrosion protection.

(i)

Installation technique, such as drilling, placing, bonding and stressing.

(j)

Any other constraints on anchoring activities.

(k)

Protection of groundwater quality and treatment or disposal of pollutants.

For the construction of anchorages, the requirements of the relevant authority shall apply. 7.6 ANCHORAGE TESTING 7.6.1 General The method used for the installation of anchorages subjected to on-site assessment tests shall be fully documented and shall meet the requirements of the relevant authority. NOTE: A typical generic procedure for the on-site assessment tests of anchorages is described in Appendix A.

Between the time of installation of an anchor and the beginning of a load test, adequate time shall be allowed to ensure that the required quality of the bond at the tendon-grout interface or, where relevant, grout-encapsulation and grout-ground interface, is achieved. Ground anchors where wedges are to be reseated during monitoring, or for any other reason, shall not be stressed to more than 75% of the tendon strength. All measuring apparatus used for anchor testing shall be calibrated, and be appropriately sensitive and accurate. The following load tests on anchors shall be carried out on site: (a)

Proof tests in accordance with Clause 7.6.2.

(b)

Suitability tests in accordance with Clause 7.6.3.

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Acceptance tests in accordance with Clause 7.6.4.

The load-carrying capacity of a grouted anchor shall be evaluated from test results in accordance with Clause 7.6.5. 7.6.2 Proof tests Where required by the designer or as specified on the drawings, proof load tests shall be carried out in advance of the construction to assess the capability of the anchor system to achieve the required resistances under the site ground conditions. NOTE: The proof tests also provide criteria for the suitability tests and acceptance tests.

7.6.3 Suitability tests Suitability tests shall be carried out to verify the rock anchor design and installation and to establish reference test values for other anchors represented by the tested anchor. Test anchors shall be representative of the installed anchors.

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Unless specified otherwise by the relevant authority, the number of suitability tests per each distinct ground condition shall be— (a)

at least 1% of the total number to be installed for temporary anchors where failure is likely to have relatively minor consequences;

(b)

at least 2% of the total number to be installed in the case of permanent anchors or of temporary anchors where there are likely to be severe consequences of failure;

(c)

at least one for each anchor type.

NOTE: Relevant load testing carried out previously may be taken into account.

The test shall comprise at least six load cycles followed by lock-off. The test duration shall be sufficient to ensure that prestress or creep fluctuations stabilize within tolerable limits. The suitability of the test procedure shall be such that conclusions may be drawn about the anchor capacity, the creep limit load and the apparent free tendon length. Attention shall be paid to the number of loading steps, the duration of these steps and application of the load cycles. NOTE: Ground variability may be taken into account by considering the different zones of homogeneous conditions or a trend of ground conditions with position on the site. The data on the installation of the anchorages should then be checked, and any deviations from normal installation should be accounted for. Such variations should be covered in part by a correct selection of the anchor for the suitability tests.

The suitability test load shall be selected in accordance with Clause 7.3 but shall not exceed 0.8 of the tendon strength for strands and 0.75 for bars. 7.6.4 Acceptance tests Acceptance tests shall be carried out to demonstrate that each of the anchorages installed has the capacity to carry the calculated design load. All grouted anchorages shall be subjected to an acceptance test before they become operational, and prior to lock-off. Acceptance tests shall be performed using procedures and acceptance criteria derived from the results of the suitability tests with the aim of proving the ability of each anchorage to support the relevant limit state loads as approved by the relevant authority.

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AS 5100.3:2017

The acceptance test procedure shall provide confirmation of the apparent free tendon length and confirmation that the tendon relaxation after lock-off will be acceptable. As a minimum, each anchorage shall be loaded to x times the design serviceability load of the anchor, where x is equal to 1.5 for permanent anchorages, and x is equal to 1.3 for temporary anchorages, or as specified otherwise by the relevant authority. NOTE: The acceptance test may be used to pre-load the anchorage in order to minimize future tendon relaxation.

7.6.5 Characteristic anchorage resistance (Rak) When deriving the characteristic anchorage resistance (Rak) from the measured anchorage capacity (Ram) in one or more suitability tests, an allowance shall be made for the variability of the ground and the variability of the effect of anchorage installation. The systematic and random components of variations in the ground conditions shall be distinguished in the interpretation of the suitability tests. As a minimum, both conditions given in Table 7.6.5 shall be satisfied using the following equation:

Rak   c Ram

. . . 7.6.5(1)

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where c is the conversion factor. The measured anchorage capacity (Ram) obtained from the suitability tests shall be equal to the lowest of the calculated loads corresponding to the first two failure mechanisms referred in Clause 7.3.3 and the creep limit load. The anchorage resistance (Ra) shall be derived from the following equation:

Ra   n Rak

. . . 7.6.5(2)

where n is the importance category reduction factor, which shall be as given in Table 7.3.3(A). The anchorage resistance (Ra) shall satisfy the following condition:

Ra  Ed

. . . 7.6.5(3)

where Ed is the design action effect on the anchorage. TABLE 7.6.5 CONVERSION FACTORS ( c) Number of suitability tests

1

2

>2

c on mean R am

0.67

0.74

0.77

c on lowest R am

0.67

0.8

0.91

7.7 MONITORING Where verification of the long-term capacity of the anchorage is required, provision for monitoring or subsequent load testing of the anchorage, or both, shall be provided as part of the design.

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SECTI ON

8

RETAI NING WALLS ABUT MENT S

AND

8.1 SCOPE OF SECTION This Section specifies requirements for the design of retaining walls and abutments, unless specified otherwise by the relevant authority. NOTE: The design of reinforced soil walls and structures is not covered by this Standard.

8.2 LOADS AND LOAD COMBINATIONS Retaining walls and abutments shall be designed for loads and other actions set out in Clause 3.2. The load combinations for strength, stability and serviceability shall be as specified in Clauses 3.3.3 and 3.4. 8.3 DESIGN REQUIREMENTS

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8.3.1 Design for strength and stability For the geotechnical and structural design of retaining walls and abutments, the provisions of Clause 2.3.3 shall apply. In designing for stability, the provisions of Clause 2.4 shall apply. As a minimum, the following limit states shall be considered: (a)

Sliding within or at the base of the structure.

(b)

Rotation of the structure.

(c)

Rupture of a structural element such as a wall, anchor, wale or strut, or failure of the connection between such elements.

(d)

Global failure.

(e)

Bearing failure.

The design geotechnical strength (Rd,g) and design structural strength (Rd,s) shall be calculated as the appropriate ultimate strength (Ru) multiplied by the appropriate strength reduction factor (). The geotechnical strength reduction factor ( g) shall be selected in accordance with Clause 2.3.5, and Tables 8.3.1(A) and 8.3.1(B), taking into account the limit state considered, and shall be subject to the approval of the relevant authority. The structural strength reduction factor (s) shall be obtained from AS 5100.5 or AS/NZS 5100.6, as appropriate. For retaining walls and abutments subjected to differential water pressures, the possibility of failure by hydraulic instability (erosion or piping) shall be considered. For soil profiles containing fine-grained soils, both short-term and long-term conditions shall be considered. Where the stability of a retaining wall or abutment depends on the passive resistance of the ground in front of the structure or abutment, the ground level in front of the wall or abutment shall be lowered by an amount h (depth of soil below nominal ground level in front of retaining wall over which passive earth pressure is to be ignored). For a cantilever structure, h shall be taken as 10% of the height above the nominal ground level in front of the structure, with a minimum value of 0.5 m. For a supported wall, h shall be taken as 10% of the height beneath the lowest support, with a minimum value of 0.5 m.  Standards Australia

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AS 5100.3:2017

The selection of the design water level shall take into account locally available data on the hydraulic and hydrogeological conditions at the site. The possibility of adverse water pressure conditions, such as those due to the presence of perched or artesian water tables or those due to saturation under heavy rainfall, shall be considered. TABLE 8.3.1(A) RANGE OF VALUES OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR RETAINING WALLS AND ABUTMENTS Range of values of g

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Method of assessment of ultimate geotechnical strength Bearing failure

Overturning, sliding and global stability Permanent structures

Temporary structures

Analysis using geotechnical parameters based on appropriate advanced in situ tests

0.45–0.55

0.55

0.60–0.70

Analysis using geotechnical parameters from appropriate advanced laboratory tests

0.40–0.50

0.55

0.55–0.65

Analysis using cone penetration test (CPT)

0.35–0.45

0.50–0.55

0.50–0.60

Analysis using standard penetration test (SPT)

0.30–0.40

0.45–0.55

0.45–0.55

TABLE 8.3.1(B) ASSESSMENT OF GEOTECHNICAL REDUCTION FACTOR ( g ) FOR RETAINING WALLS AND ABUTMENTS Lower end of range

Upper end of range

Limited site investigation

Comprehensive site investigation

Simple methods of calculation

More sophisticated design method

Limited construction control

Rigorous construction control

Severe consequences of failure

Less severe consequences of failure

Significant cyclic loading

Mainly static loading

Use of published correlations for design parameters

Use of site-specific correlations for design parameters

8.3.2 Calculation of earth pressures Calculation of the design action effects arising from earth pressures shall take into account the following factors: (a)

Surcharges on and slope of the ground surface.

(b)

Inclination of the wall or structure face to the vertical.

(c)

Water table levels, variations in these levels and seepage forces in the ground.

(d)

Amount and direction of wall movement relative to the ground.

(e)

Shear strength and unit weight of the ground.

(f)

Rigidity of the wall and the supporting system.

(g)

Wall roughness.

(h)

Effects of any compaction during construction.

(i)

Influence of surcharge loadings adjacent to the wall or abutment.

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Earthquake loads. NOTES: 1 New bridge abutments should be designed using coefficient of earth pressure at rest (Ko) to limit long-term displacements, and consequent serviceability issues. 2 Traditional methods of calculating active earth pressures (e.g., Rankine’s method or Coulomb’s method) may be employed. 3 For passive earth pressure calculation, traditional methods such as Rankine’s method and Coulomb’s method are often unreliable. It is preferable to use a more rigorous method such as that described by Lee and Herington (1972), and Caquot and Kerisel (1948) (see Bibliography). 4 Reactive soils should be excluded from use behind bridge abutments.

8.3.3 Design for eccentric and inclined loads In assessing the ultimate geotechnical strength (Ru,g), allowance shall be made for the possibility of very high edge stresses and a reduced effective contact area between the retaining wall or abutment footing and the ground as a result of load eccentricity.

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8.3.4 Design for serviceability For the serviceability design of retaining walls and abutments, the provisions of Clause 2.5 shall apply. In estimating the settlement and horizontal displacements, account shall be taken of the stiffness of the ground and the structural elements, and of the sequence of construction. Allowable displacements for walls and abutments shall be established taking into account the tolerance to deformation of the supported structures and services. NOTES: 1 When no movement of the retaining structure relative to the ground takes place, the earth pressure may be calculated for the at-rest state of stress in the ground. This stress state will depend on the stress history of the ground. At-rest conditions can be expected to exist in the ground behind a retaining structure if the horizontal movement of the structure is less than about 0.05% of the unsupported height of the structure. 2 If a linear analysis is employed, the stiffnesses for the ground and structural elements should be appropriate for the level of deformation computed.

8.3.5 Design for durability Design for durability shall be in accordance with Clause 4. The design life shall be in accordance with AS 5100.1. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements for durability in the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used in the structure, the requirements of the relevant authority shall apply. 8.4 STRUCTURAL DESIGN AND DETAILING 8.4.1 General Structural design and detailing for retaining walls and abutments built of concrete and steel shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements of the relevant Standard for that material shall apply to the structural design and detailing of the structure, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the structure, the requirements of the relevant authority shall apply.  Standards Australia

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AS 5100.3:2017

Tensile stresses shall not be permitted in masonry and unreinforced concrete retaining walls and abutments. 8.4.2 Joints Full depth vertical contraction joints shall be provided in long concrete retaining walls and abutments to control indiscriminate shrinkage cracking. Where the structure is founded directly on rock, a reduced joint spacing shall be used. NOTE: Contraction joints are recommended at a spacing of 8 m to 10 m along substructure members on other than rock. Where the structure is founded on rock, a reduced spacing of 5 m is recommended.

Where expansion joints are provided, suitable compressible jointing material shall be provided in the expansion joints. NOTE: Expansion joints are recommended at a spacing of 30 m along substructure members.

Contraction or expansion joints shall also be provided where abrupt changes in structure section occurs. Expansion joints in counterfort walls shall be located between double counterforts or midway between counterforts. Where there is the possibility of water seepage through joints, either a water-stop within the joint or a flexible waterproof membrane behind the joint shall be used. Accessed by Brandon & Associates refreshed 170613 on 14 Feb 2019 (Document currency not guaranteed when printed)

Provision for shear transfer shall be made for all joints. 8.4.3 Shrinkage and temperature reinforcement All reinforced concrete retaining walls and abutments shall be reinforced for shrinkage and temperature effects to the requirements of AS 5100.5. 8.5 MATERIALS AND CONSTRUCTION REQUIREMENTS Materials and construction requirements for retaining walls and abutments built of concrete and steel shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements of the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the structure, the requirements of the relevant authority shall apply. 8.6 DRAINAGE Unless hydrostatic pressure is taken into account in design, effective drainage shall be provided behind retaining walls and abutments to permanently relieve water pressures. Where the safety and serviceability of the design depends on the successful performance of the drainage system, the consequences of failure of the drainage system shall be considered, and measures shall be taken to ensure continuing performance of the drainage system. Details of the drainage system shall be subject to the approval of the relevant authority. NOTE: The seepage quantities, pressures, and chemical content of water emerging from a drainage system should be considered, and appropriate measures taken to dispose of this water.

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SECTI ON

9

BURIED

STRUCTURES

9.1 GENERAL The requirements for the design of structures where soil and rock loads form a significant proportion of the total loads on the structure shall be as set out herein unless specified otherwise by the relevant authority. Precast reinforced concrete box culverts shall be designed in accordance with AS 1597.2, for the sizes specified in that Standard. For the design of sizes larger than those specified in AS 1597.2, the principles of the appropriate Standard shall apply. NOTE: The design of buried arch structures is a specialized field and should be carried out by experienced design engineers.

9.2 LOADS AND LOAD COMBINATIONS Buried structures shall be designed for the loads and other actions set out in Clause 3.2.

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The load combinations for strength, stability and serviceability shall be as specified in Clauses 3.3.3 and 3.4. The following additional loads and actions shall be considered when determining the design loads for buried structures: (a)

Variations in soil density, stiffness, or strength across the structure, or through the depth of the soil over and around the structure.

(b)

The effects of structure stiffness on the interaction between the ground and the structure.

(c)

Transverse or longitudinal loads due to fill slopes or retaining walls above the structure, or construction on a slope.

(d)

Loads in precast elements occurring during handling and erection.

(e)

Varying load and restraint conditions during backfilling operations.

(f)

Locked-in stresses due to compaction loads and deflection of the structure during backfilling.

(g)

Loads due to groundwater, taking into account variations in the level of groundwater.

(h)

Effects due to distortion of the structure.

The design shall take into account non-linear and non-elastic behaviour of the soil and the structure where these effects may be significant. Axial loads shall be considered. 9.3 DESIGN REQUIREMENTS 9.3.1 Design for strength and stability For the geotechnical and structural design of buried structures, the provisions of Clause 2.3.3 shall apply. In designing for stability of buried structures, the provisions of Clause 2.4 shall apply. The design geotechnical strength (Rd,g) and design structural strength (Rd,s) shall be calculated as the appropriate ultimate strength (Ru) multiplied by the appropriate strength reduction factor (). The structural strength reduction factor (s) shall be obtained from AS 5100.5 or AS/NZS 5100.6, as appropriate. The geotechnical strength reduction factor ( g) shall be selected in accordance with Clause 2.3.5, and Tables 9.3.1(A) and 9.3.1(B).

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Consideration shall be given to the possibility of failure due to loss of overall stability. The stability of the structure in all directions, for all possible modes of failure, shall be considered. NOTE: The longitudinal stability of segmental structures such as culverts passing under embankment slopes, or constructed on a steep longitudinal gradient, should be given particular attention.

Foundations of buried structures shall be designed in accordance with Clauses 5 and 6, where appropriate. TABLE 9.3.1(A) RANGE OF VALUES OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR BURIED STRUCTURES

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Method of assessment of ultimate geotechnical strength

Range of values of g

Analysis using geotechnical parameters based on appropriate advanced in situ tests

0.50–0.65

Analysis using geotechnical parameters from appropriate advanced laboratory tests

0.45–0.60

Analysis using cone penetration test (CPT)

0.40–0.50

Analysis using standard penetration test (SPT)

0.35–0.40

TABLE 9.3.1(B) ASSESSMENT OF GEOTECHNICAL STRENGTH REDUCTION FACTOR ( g ) FOR BURIED STRUCTURES Lower end of range

Upper end of range

Limited site investigation

Comprehensive site investigation

Simple methods of calculation

More sophisticated design method

Limited construction control

Rigorous construction control

Severe consequences of failure

Less severe consequences of failure

Significant cyclic loading

Mainly static loading

Use of published correlations for design parameters

Use of site-specific correlations for design parameters

9.3.2 Design for serviceability For the serviceability design of buried structures, the provisions of Clause 2.5 shall apply. 9.3.3 Design for durability Design for durability shall be in accordance with Section 4. The design life shall be in accordance with AS 5100.1. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements for durability in the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used in the structure, the requirements of the relevant authority shall apply.

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9.4 STRUCTURAL DESIGN AND DETAILING Structural design and detailing for buried structures built of concrete and steel shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Buried structures may be subject to high axial loads. Compression reinforcement for the design axial loads for concrete structures shall be designed in accordance with the requirements of AS 5100.5, where necessary, and shall meet the requirements of the relevant authority. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements of the relevant Standard for that material shall apply to the structural design and detailing of the structure, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the structure, the requirements of the relevant authority shall apply. 9.5 MATERIALS AND CONSTRUCTION REQUIREMENTS

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Materials and construction requirements for buried structures built of concrete and steel shall be in accordance with AS 5100.5 or AS/NZS 5100.6, as appropriate. Where materials other than concrete and steel are to be used for the construction of the structure, the requirements of the relevant Standard for that material shall apply, unless specified otherwise by the relevant authority. Where no Standard applies to the materials used for the construction of the structure, the requirements of the relevant authority shall apply.

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AS 5100.3:2017

APPENDIX A

ON-SITE ASSESSMENT TESTS OF ANCHORAGES (Informative) A1 SCOPE This Appendix provides a typical generic procedure for on-site assessment test of anchorages. A2 DEFINITIONS AND NOTATION A2.1 Definitions For the purpose of this Appendix, the definitions below apply. A2.1.1 Free length (Lfr)

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That length, in metres, of a tendon between the anchorage assembly and the bond length, or transition length, which does not transfer any tendon load to the surrounding ground, concrete or other material through which the anchor passes. A2.1.2 Effective free length (Lef) The apparent length, in metres, over which the tendon is assumed to extend elastically as determined by stressing tests. NOTE: The effective length is calculated from the load/elastic displacement data following testing, to indicate the length of tendon that is apparently fully decoupled from the surrounding grout.

A2.1.3 Jacking load (Tj) The jacking force, in kilonewtons, that produces the lock-off load, taking into account any anchorage friction and draw-in losses. A2.1.4 Lock-off load (To) The load, in kilonewtons, equal to the design working load plus an allowance for loss of prestress. A2.1.5 Test load (Tp) The maximum load, in kilonewtons, to which a tendon is subjected in the short term for proof, suitability and acceptance tests. A2.1.6 Minimum breaking load (Tu) The minimum breaking load, in kilonewtons, of the tendon. NOTE: The minimum breaking load is calculated from the minimum strength of the component material as nominated by the supplier and verified by test.

A2.1.7 Initial datum load (Ta) The initial load, in kilonewtons, selected for proof, suitability and acceptance tests. A2.1.8 Initial residual load (Tri) The load, in kilonewtons, in the tendon immediately after lock-off. NOTE: The initial residue load is usually measured by a lift-off test.

A2.1.9 Residual load (Tr) The load, in kilonewtons, remaining in the tendon at any time after lock-off, usually measured by a lift-off test. www.standards.org.au

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A2.1.10 Lift-off test The test to determine the residual load in the tendon. NOTE: Lift-off occurs when an applied load in excess of the residual load causes a very small but perceptible movement of the stressing head, nut or other locking device away from the anchor baseplate (usual range of movement 0.2–1.0 mm).

A2.1.11 Tendon bond length (Lb) The length of tendon bonded directly to the grout capable of transmitting the ultimate tensile capacity of the tendon. A2.2 Notation The following symbols are used in this Appendix for on-site assessment tests of anchorages:

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Symbol

Definition

At

cross-sectional area of a tendon, in millimetres square

Et

modulus of elasticity of steel tendon, in megapascals

Lb

tendon bond length, in millimetres

Lef

effective free length of tendons, in millimetres

Lfr

free length, in millimetres

Ta

initial datum load, in kilonewtons

Tj

jacking load, in kilonewtons

To

lock-off load, in kilonewtons

Tp

test load, in kilonewtons

Tr

residual load, in kilonewtons

Tri

initial residual load, in kilonewtons

Tu

minimum breaking load of tendon, in kilonewtons

Le

measured elastic extension of the tendon at each load stage, in millimetres

Lr

calculated elastic extension of tendon under test load (Tp), in millimetres

A3 LOAD TESTS AND ASSESSMENT A3.1 General The procedure for load tests and assessment in this Appendix should be adopted for all anchors that are specified or directed to be subject to load tests. A3.2 Load testing A3.2.1 General For each test, load the anchor in stages in accordance with the specified test procedure. In this Standard, three types of on-site load tests are specified (see Clause 7.6): (a)

Proof.

(b)

Suitability.

(c)

Acceptance.

Test the anchor at the frequency specified in Table A1, unless specified otherwise.

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AS 5100.3:2017

TABLE A1 MINIMUM TESTING FREQUENCY Paragraph

Type of test

Type of ground anchor (see Note)

Minimum frequency of testing each type of ground anchor and each ground condition

A3.2.3

Proof

Exploratory or investigation

As required by designer or as specified on the drawings

A3.2.4

Suitability

Low risk and temporary

 1% of installed anchors or 1, whichever is greater

A3.2.4

Suitability

High risk and temporary Normal risk and permanent

 2% of installed anchors or 2, whichever is greater

A3.2.4

Suitability

Critical and permanent

 2% of installed anchors or 3, whichever is greater

A3.2.5

Acceptance

All

All remaining anchors

NOTE: For classification of ground anchors, see Section 7.

A3.2.2 Loading and monitoring

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Apply and release loads smoothly to prevent shock or dynamic loading of the anchor. During all tests, monitor and record the applied load and tendon extension at each load increment. To assess the behaviour of the anchor at peak load, monitor performance by measurement of load loss while the extension is kept constant as verified by measurements (i.e. creep test). Monitor anchor performance at lock-off by carrying out accurate lift-off tests at specified periods after lock-off (i.e. load monitoring). Where proven accurate load cells are part of the jacking system, both these tests may be carried out at test load (Tp) and lock-off load (To) to verify anchor performance. A3.2.3 Proof tests Carry out proof tests in advance of the installation of working anchors to verify for the designer that the failure load or the bond capacity of an anchor at the grout/ground interface provides the required resistance in the working anchor. The resistances achieved relate to the ground conditions, anchor materials used and the construction methods adopted. Proof tests may be specified where anchors are to be used in ground conditions not yet tested by previous proof tests or where greater design loads are to be used than those adopted in similar ground conditions. At a site where variable ground conditions are expected, proof tests may be used to assess the performance of anchors founded in different strata. Anchors for proof tests are loaded more rigorously than working anchors, so it is generally necessary to increase the area of the tendon to accommodate the higher load requirements, or to test shorter bonded lengths to induce a grout/ground interface failure. Load the anchor to failure or to a maximum test load; the test load to not exceed 80% for strands or 75% for bars of the minimum breaking load of the tendon (Tu), whichever is lower. Throughout proof tests, investigate the characteristics of load loss at each load cycle peak (see Table A2). Failure is deemed to be reached when at constant extension the load loss due to creep exceeds 2% of the maximum test load over a 5 min period. www.standards.org.au

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TABLE A2 RECOMMENDED LOAD INCREMENTS AND MINIMUM PERIODS OF OBSERVATION FOR PROOF TESTS Load increments (% of T u ) Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Cycle 6

Cycles 7 and 8

Minimum period of observation, min

5

5

5

5

5

5

5

1

10

20

30

40

50

60

70 (65*)

1

15

25

35

45

55

65

75 (70*)

1

20

30

40

50

60

70

80 (75*)

15

15

20

30

40

40

50

50

1

10

10

15

20

20

30

30

1

5

5

5

5

5

5

5

1

* For bars

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NOTE: Plot load-displacements as the test proceeds. At an early stage, observe trends and, in particular, yield of the bond length as failure approaches.

Assess the anchorage resistance (Ra) in accordance with Clause 7.6.5. Proof tests may be extended as required to verify the actual performance of any component of the anchor, these being typically— (a)

bond capacity at the tendon to grout interface;

(b)

bond capacity of the duct to grout interface;

(c)

integrity of corrosion protection system during and after completion of testing; and

(d)

performance of new anchor systems (e.g. multiple anchor, removable anchor or carbon fibre tendon systems, etc.).

Do not use anchors subjected to proof tests as working anchors. A3.2.4 Suitability tests Prior to carrying out a suitability test, take into account the results of proof tests or of relevant prior published data that will form the basis of or validate the design of working ground anchors, the required resistance at each interface and the ability of the anchor to sustain load. Tendons, drilling, grouting and construction methods for suitability tests have to be identical to those proposed for the working anchors. Suitability test objectives need to demonstrate— (a)

acceptable load/extension behaviour of the anchor under cyclic loading and the magnitude of the elastic extension and permanent displacement of the tendon;

(b)

that tendon extensions, following corrections for head movement, etc., lie between 90% and 110% of the values calculated using design load, tendon area, tendon elastic modulus and design free anchor length [see Paragraph A3.2.6.2(c)];

(c)

that the calculated value of apparent tendon free length lies between 90% and 110% of the design free anchor length, calculated using the measured elastic extension values [see Paragraph A3.2.6.2(f)];

(d)

that in the event of non-conformity with design values, the repeatability of load/extension characteristics can be verified using extra test cycles [see Paragraph A3.2.6.2(g)]; and

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(e)

AS 5100.3:2017

that creep characteristics following acceptance testing [see Paragraph A3.2.6.2(e)] are acceptable.

Use the results of suitability tests to verify the performance of represented working anchors constructed in exactly the same way and under identical ground conditions at the frequency specified in Table A1. Where varying ground conditions are known or are encountered, install and carry out suitability tests on additional anchors. Suitability anchors, subject to satisfactory performance as assessed by conformance to the relevant acceptance criteria of Paragraph A3.2.6.2, may be used as working anchors. The test load (Tp) for suitability anchors have to be selected in accordance with Clause 7.3.3; the test load to not exceed 0.8 Tu for strands or 0.75 Tu for bars. Loading cycles and minimum periods of observation are given in Table A3. Load suitability anchors to test load (Tp) in a minimum of six load cycles. Where relevant proof tests have previously been carried out, load suitability anchors using one initial unmonitored cycle and three repeat cycles to test load (Tp). TABLE A3

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RECOMMENDED LOAD INCREMENTS AND MINIMUM PERIODS OF OBSERVATION FOR SUITABILITY TESTS Load levels (% of test load T p )

Minimum period of observation, min

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Cycle 6

10

10

10

10

10

10

1

—

25

40

55

70

85

1

25

40

55

70

85

100

15

—

25

40

55

70

85

1

10

10

10

10

10*

10

1

* Full unloading is permitted for installation of the permanent wedges

A3.2.5 Acceptance tests Carry out an acceptance test on any working anchor not subjected to a suitability test. For anchors up to 15 m long, carry out one unmonitored preliminary loading cycle to test load (Tp). Load in four equal increments from initial or datum load (Ta) to test load (Tp) and unload in four equal increments from (Tp) to (Ta). Table A4 provides observation and recording periods. Observe and record creep test results and relaxation to lock-off load (To) and apply the relevant acceptance criteria of Paragraph A3.2.6.2 to assess conformance.

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TABLE A4 RECOMMENDED LOAD INCREMENT AND MINIMUM PERIODS OF OBSERVATION FOR ACCEPTANCE TESTS Load levels [% test load (Tp )]

Minimum period of observation min

10

1

40

1

70

1

100

15

70

1

40

1

10

1

A3.2.6 Assessment and acceptance criteria A3.2.6.1 General

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Assess all ground anchors covered by this Standard at test load (Tp) and lock-off load (To). Assess anchor performance by carrying out suitability tests on suitability anchors before testing the working anchors using acceptance tests. Anchors have to conform to all the acceptance criteria of Paragraph A3.2.6.2. Only accept a working load for an anchor that conforms to all the acceptance criteria of Paragraph A3.2.6.2. A3.2.6.2 Assessment criteria and mode of application for all suitability anchors and all acceptance tests The procedure is as follows: (a)

Load the anchor in a single unmonitored load cycle up to test load (Tp) and return to initial or datum load (Ta). This pre-load cycle is intended to— (i)

accommodate wedge draw-in of tendon-gripping system;

(ii)

overcome initial friction forces;

(iii) achieve bedding of the bearing plate or cast-in anchorage;

(b)

(iv)

achieve displacement of the structure;

(v)

reduce the contribution of extraneous displacements;

(vi)

allow a more accurate determination of elastic extension during the monitored cycle.

Calculate the elastic extension (δLr) of the tendon under test load (Tp) from initial or datum load ( Ta), using data from the anchor assembly schedule, as follows:

Lr 

T

p



 Ta Lfr At E t

. . . A3.2.6.2(1)

where

 Standards Australia

At

= cross-sectional area of steel in the tendon, in millimetres square

Et

= modulus of elasticity of steel tendon, in megapascals

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AS 5100.3:2017

Lfr = free length of tendon between top of bond length and wedges at rear of jack, in millimetres

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δLr = calculated elastic extension of tendon under test load, in millimetres Ta

= initial or datum load, in kilonewtons

Tp

= test load, in kilonewtons

(c)

Calculate values of 90% and 110% elastic extension at test load (Tp) from initial or datum load (Ta) to provide criteria for assessing anchorage conformance; that is, measured elastic extensions δLe between 0.9δLr and 1.1δLr will be conforming.

(d)

Where the measured elastic extension is outside these limits, carry out as appropriate, while the stressing equipment is in place, two additional load cycles to verify load/extension repeatability [see Step (g)].

(e)

For suitability tests and acceptance tests, carry out a program of cyclic loading and unloading using the load increments and minimum periods of observation given in Table A3 and Table A4 respectively. After the peak load in each cycle is reached, take measurements of the load loss with the deformation held constant for a time interval of 5 min. This time may be subsequently increased to 15 min and then to 50 min to obtain compliance to a limiting value as given in Table A5.

(f)

Based on the load/extension results, calculate the effective tendon free length (Lef) at test load (Tp) using data from the anchor assembly schedule and the load test records and calculate the limits for acceptance as follows: 0.9Lfr  Lef  (Lfr + 0.5Lb)

. . . A3.2.6.2(2)

or 0.9Lfr  Lef  1.1 Lfr

. . . A3.2.6.2(3)

and

Lef 

Le At E t

T

p

 Ta

 10

6

. . . A3.2.6.2(4)

where

At

= cross-sectional area of steel in the tendon, in millimetres square

Et

= modulus of elasticity of the tendon, in megapascals

Lb

= tendon bond length, in millimetres

Lef = effective free length of the tendon between top of bond length and wedges at rear of jack, in millimetres Lfr = free length of tendon between top of bond length and wedges at rear of jack, in millimetres Ta

= initial datum load, in kilonewtons

Tp

= test load, in kilonewtons

δLe = measured elastic extension of the tendon at each load stage, in millimetres If the corrected elastic extension lies within these limits, the effective free length satisfies the acceptance criteria.

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(g)

52

If the anchor does not satisfy either of these limits, reload the anchor in two cycles to test load (Tp). Provided Lef  Lfr + 0.6Lb and the anchor has repeatable load/extension behaviour in the second cycle as demonstrated by the extension in the second cycle being within 5% of that in first cycle, this criterion is satisfied. If this criterion is not satisfied, extend the test with the approval of the relevant authority or replace or down rate the anchor.

(h)

The initial residual load (Tri) measured by lift-off test immediately after lock-off has to be not less than 110% and not greater than 115% of specified lock-off load (To). If the initial residual load (Tri) is less than 110% of the specified lock-off load (To), increase the jacking force (Tj) and repeat the test cycles.

The residual load (Tr) measured by lift-off test at 48 h after lock-off has to be not less than 96% of the initial residual load (Tri). Where the residual load (Tr) at 48 h after lock-off is less than 96% of the initial residual load (Tri), the test may be repeated for two further 48 h periods. If the residual load (Tr) at 96 h after lock-off is greater than 94% of Tri or at 144 h is greater than 93% of Tri, the residual load criterion is satisfied.

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If this criterion is still not satisfied, extend the test with the approval of the relevant authority or replace or down rate the anchor. TABLE A5 LIMITING VALUES OF LOAD LOSS WITH TIME

 Standards Australia

Observation period, min

Limiting load loss within observation period

0 to 5

Max. 2% of T p

5 to 15

Max. 1% of T p

15 to 50

Max. 1% of T p

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BIBLIOGRAPHY AS 4139

Fibre-reinforced concrete pipes and fittings

3725

Loads on buried concrete pipes

4312

Atmospheric corrosivity zones in Australia

AS/NZS 2041 Buried corrugated metal structures 2041.1 Part 1: Design methods 4058

Precast concrete pipes (pressure and non-pressure)

Lee, I.K. and Herington, J.R., A Theoretical Study of the Pressures Acting on a Rigid Wall by a Sloping Earth or Rock Fill, Geotechnique, 22(1), 1972, 1-26.

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Caquot, A. and Kerisel, J., Tables for the calculation of passive pressure, active pressure and bearing capacity on foundations, Gauthier-Villars, Paris, 1948.

www.standards.org.au

 Standards Australia

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AS 5100.3:2017 54

NOTES

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55

NOTES

AS 5100.3:2017

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AS 5100.3:2017 56

NOTES

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