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AS 1597.2—1996



Australian Standard Precast reinforced concrete box culverts



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



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



This Australian Standard was prepared by Committee CE/26, Precast Reinforced Concrete Box Culverts. It was approved on behalf of the Council of Standards Australia on 5 December 1995 and published on 5 April 1996.



The following interests are represented on Committee CE/26: Association of Consulting Engineers, Australia Australian Chamber of Commerce and Industry Australian Geomechanics Society AUSTROADS Cement and Concrete Association of Australia Concrete Pipe Association of Australasia Institute of Municipal Engineering, Australia Institution of Engineers, Australia National Precast Concrete Association Railways of Australia Swinburne Institute of Technology University of Adelaide



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



University of Sydney



Review of Australian Standards. To keep abreast of progress in industry, Australi an Standards are subject to periodic review and are kept up to date by the issue of amendments or new editions as necessary. It is important therefore that Standards users ensure that they are in possession of the latest editi on, and any amendments thereto. Full details of all Australian Standards and related publications wil l be found in the Standards Australia Catalogue of Publi cations; this information is supplemented each month by the magazine ‘The Australian Standard’, which subscribing members receive, and which gives details of new publications, new editions and amendments, and of withdrawn Standards. Suggestions for improvements to Australian Standards, addressed to the head office of Standards Australia, are welcomed. Noti fication of any inaccuracy or ambiguity found in an Australian Standard should be made wit hout delay in order that the matter may be investigated and appropriate action taken.



This Standard was issued in draft form for comment as DR 94049.



AS 1597.2—1996



Australian Standard Precast reinforced concrete box culverts



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



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



PUBLISHED BY STANDARDS AUSTRALIA (STANDARDS ASSOCIATION OF AUSTRALIA) 1 THE CRESCENT, HOMEBUSH, NSW 2140 ISBN 0 7337 0267 8



AS 1597.2 — 1996



2



PREFACE This Standard was prepared by the Standards Australia Committee CE/26 on Precast Reinforced Concrete Box Culverts. In the course of preparation of this Standard, the Committee found that there was support for specifying design by prototype testing as well as for specifying limit states design using load factors. The Committee agreed that both criteria be specified as alternative but not coincidental as a basis for design and acceptance of the culverts and culvert units. The objective of this Standard is to set out minimum requirements for the design, testing, manufacture and installation of precast reinforced concrete rectangular box culverts of span 1500 mm or greater. AS 1597.1— 1974, Precast reinforced concrete box culverts, Part 1: Small culverts not exceeding 1200 mm width and 900 mm depth , covers box culverts up to 1200 mm span and 900 mm height. It is intended to revise AS 1597.1 and to extend the range of that Standard to include box culverts up to 1200 mm span and 1200 mm height. The term ‘culvert cell’ is commonly used to refer to a complete conduit made up of a number of units placed end-to-end. For the purposes of this Standard, the term ‘culvert’ is used to refer to a single cell or a multiple cell structure, and associated link slabs and base slabs.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



The terms ‘normative’ and ‘informative’ have been used in this Standard to define the application of the appendix to which they apply. A ‘normative’ appendix is an integral part of a Standard, whereas an ‘informative’ appendix is only for information and guidance.



 Copyri ght



STANDARDS AUSTRALIA



Users of Standards are reminded that copyri ght subsists in all Standards Austr alia publi cati ons and software. Except where the Copyri ght Act all ows and except where provided for below no publications or software produced by Standards Australi a may be reproduced, stored in a retr ieval system in any form or transmitt ed by any means without prior permission in writ ing from Standards Australi a. Permission may be condit ional on an appropri ate royalty payment. Requests for permission and informati on on commercial software royalt ies should be directed to the head offi ce of Standards Austr alia. Standards Australi a wil l permit up to 10 percent of the technical content pages of a Standard to be copied for use exclusively in-house by purchasers of the Standard without payment of a royalty or advice to Standards Austr alia. Standards Austr alia wil l also permit the inclusion of it s copyri ght material in computer soft ware programs for no royalty payment provided such programs are used exclusively in-house by the creators of the programs. Care should be taken to ensure that materi al used is fr om the curr ent edit ion of the Standard and that it is updated whenever the Standard is amended or revised. The number and date of the Standard should therefore be clearly identif ied. The use of materi al in print form or in computer software programs to be used commercially, with or without payment, or in commercial contracts is subject to the payment of a royalty. This policy may be vari ed by Standards Austr alia at any ti me.



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AS 1597.2 — 1996



CONTENTS Page



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



SECTION 1 SCOPE AND GENERAL 1.1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 APPLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 REFERENCED DOCUMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.5 NOTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.6 USE OF ALTERNATIVE MATERIALS OR METHODS . . . . . . . . . . . . . . . . 11 1.7 TYPES OF CULVERTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.8 CLASSIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 SECTION 2 MATERIALS, MANUFACTURE AND DIMENSIONING 2.1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 FORMWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 REINFORCEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 CONCRETE MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 SPECIFICATION AND MANUFACTURE OF CONCRETE . . . . . . . . . . . . . 2.6 HANDLING, PLACING AND FINISHING OF CONCRETE . . . . . . . . . . . . . 2.7 CURING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 JOINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.10 COVER TO REINFORCEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.11 MEASUREMENT OF DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.12 TOLERANCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13 PROVISION FOR LIFTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.14 WORKMANSHIP AND FINISH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.15 DEFECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16 MARKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.17 FINISHING AND REPAIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .



14 14 14 14 14 15 15 16 16 16 18 19 19 19 20 21 21



SECTION 3 DESIGN REQUIREMENTS AND PROCEDURES 3.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 DESIGN LOADS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 LOAD EFFECT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 THEORETICAL STRENGTH AND SERVICEABILITY CALCULATIONS . . 3.5 REINFORCEMENT DETAILING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .



22 23 28 29 30



SECTION 4 LOAD TESTING FOR DESIGN 4.1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 GENERAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 TEST SPECIMENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 TEST LOADS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 PROTOTYPE PROOF LOAD TESTS FOR SERVICEABILITY . . . . . . . . . . . 4.6 PROTOTYPE PROOF LOAD TESTS FOR ULTIMATE STRENGTH . . . . . . . 4.7 FAILURE LOAD TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .



32 32 32 34 35 39 40



AS 1597.2 — 1996



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Page



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SECTION 5 ROUTINE SAMPLING AND TESTING 5.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 REQUIRED TESTS . . . . . . . . . . . . . . . . . . . . . 5.3 SAMPLING FOR LOAD TESTING . . . . . . . . . 5.4 COMPLIANCE . . . . . . . . . . . . . . . . . . . . . . . . 5.5 ACCEPTANCE . . . . . . . . . . . . . . . . . . . . . . . .



.. .. .. .. ..



. . . . .



.. .. .. .. ..



.. .. .. ... . ... ... .. ......... . ... .. ... . .. .. .. ..



.... ... . .... ... . ... .



... .. . ... ... ...



45 45 46 46 46



SECTION 6 INSTALLATION 6.1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 EXCAVATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 FOUNDATION PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 PLACING PRECAST UNITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 COMPACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 BACKFILLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7 CONSTRUCTION LOADS ON CULVERTS . . . . . . . . . . . . . . . . . . . . . . . .



47 47 47 47 48 48 49



APPENDICES A PURCHASING GUIDELINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B MEANS FOR DEMONSTRATING COMPLIANCE WITH THIS STAND ARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C LOW PRESSURE STEAM CURING OF CONCRETE UNITS . . . . . . . . . . . D METHODS FOR COVER TESTING OF UNITS . . . . . . . . . . . . . . . . . . . . E MEASUREMENT OF CRACK WIDTH . . . . . . . . . . . . . . . . . . . . . . . . . . F GRAVITY FORCES AND DENSITIES OF MATERIALS FOR CULVERT DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G FLOW CHARTS FOR PROTOTYPE TESTING . . . . . . . . . . . . . . . . . . . . . H METHOD FOR CRACK LOAD TESTING (ROUTINE TESTING) OF CULVERT UNITS LINK OR BASE SLABS . . . . . . . . . . . . . . . . . . . . I TABLES OF SERVICEABILITY TEST LOADS FOR STAND ARD CULVERT UNITS AND LINK SLABS . . . . . . . . . . . . . . . . . . . . . . . . . . . J TABLES OF BASIC TEST LOADS FOR STAND ARD CULVERT UNITS AND LINK SLABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K SAMPLING SCHEME FOR ROUTINE TESTING . . . . . . . . . . . . . . . . . . .



First publi shed as AS 1597.2— 1996.



. 50 . . . .



51 53 54 56



. 57 . 58 . 64 . 68 . 70 . 84



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AS 1597.2 — 1996



STANDARDS AUSTRALIA Australian Standard 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) S E C T I O N



1



S CO P E



A N D



G E NE R A L



1.1 SCOPE This Standard sets out minimum requirements for the design, testing, manufacture and installation of precast reinforced concrete rectangular box culverts for conveying water not under pressure, and for carrying roadway and railway loadings permitted by Australian road and railway authorities. Design requirements are based on the methods of limit state design, using theoretical strength and serviceability calculations, or prototype testing. This Standard is applicable to rectangular precast culvert units having a maximum length of 3600 mm, a maximum height of 4200 mm and a span from 1500 mm to 4200 mm and having a height of fill over the top of the culvert unit not exceeding 10 m. NOTES: 1 Guidelines to purchasers on requirements that may need to be agreed upon at the time of calling for tenders or quotations are detailed in Appendix A. 2 Methods for demonstrating compliance with this Standard are given in Appendix B.



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3 For precast reinforced box culverts of internal dimensions exceeding 4200 mm span or height, additional design considerations may be necessary. Additional design considerations are required for special culverts, e.g. skewed ends, culvert units with large holes, culverts subject to loading other than standard roadways and railways loadings.



1.2 APPLICATION All large precast reinforced concrete rectangular box culverts designed, manufactured, tested and installed in accordance with this Standard shall comply with the relevant requirements of Sections 1 to 6, with the alternative requirements as applicable. 1.3 REFERENCED DOCUMENTS The following documents are referred to in this Standard: AS 1012 1012.1 1012.8 1012.9



Methods of testing concrete Part 1: Sampling of fresh concrete Part 8: Method for making and curing concrete compression, indirect tensile and flexure test specimens, in the laboratory or in the field Part 9: Method for the determination of the compressive strength of concrete specimens



1199



Sampling procedures and tables for inspection by attributes



1289 1289.5 1289.5.1.1



Methods of testing soils for engineering purposes Part 5: Soil compaction and density tests Determination of the dry density/moisture content relation of a soil using standard compactive effort



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AS 1597.2 — 1996



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AS 1289.5.3.2 1289.5.4.1 1289.C6.1 1289.E3.5 1289.E5.1



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



1289.E6.1



Determination of the field dry density of a soil — Sand replacement method using a sand pouring can, with or without a volume displacer Compaction control test — Dry density ratio, moisture variation and moisture ratio Part C: Soil classification tests — Determination of the particle size distribution of a soil —Standard method of analysis by sieving Part E: Soil compaction and density tests — Determination of the field dry density of a soil— Water replacement method Part E: Soil compaction and density tests— Determination of minimum and maximum dry density of a cohesionless material Part E: Soil compaction and density tests — Compaction control test— Density index method for a cohesionless material



1302



Steel reinforcing bars for concrete



1303



Steel reinforcing wire for concrete



1304



Welded wire reinforcing fabric for concrete



1379



The specification and manufacture of concrete



1399



Guide to AS 1199—Sampling procedures and tables for inspection by attributes



1478



Chemical admixtures for concrete



1726



Geotechnical site investigations



2758 2758.1



Aggregates and rock for engineering purposes Part 1: Concrete aggregates



3582 3582.1 3582.2 3582.3



Supplementary cementitious materials for use with portland cement Part 1: Fly ash Part 2: Slag— Ground granulated iron blast-furnace Part 3: Silica fume



3600



Concrete structures



3972



Portland and blended cements



AS/NZS ISO 8402



Quality management and quality assurance —Vocabulary



ISO 9000 Quality management and quality assurance standards ISO 9000.1 Part 1: Guidelines for selection and use ISO 9004 Quality management and quality system elements ISO 9004.1 Part 1: Guidelines SAA HB18 HB18.28



Guidelines for third party certification and accreditation Guide 28 — General rules for a model third-party certification scheme for products



AUSTROADS 1992 AUSTROADS Bridge Design Code ANZRC 1.4



Railway Bridge Design Manual



DEFINITIONS For the purpose of this Standard, the definitions below apply.



1.4.1 1.4.1.1



Administrative Approved —approved by the regulatory authority or its nominated representative.



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AS 1597.2 — 1996



1.4.1.2 Informative —not an integral requirement of this Standard and provided for information only. 1.4.1.3 Manufacturer —person(s) or corporate body responsible for the manufacture of the precast reinforced concrete box culverts. 1.4.1.4



Normative—an integral and mandatory requirement of this Standard.



1.4.1.5 Purchaser—person(s), corporate body or regulatory authority for whom the manufacturer has contracted to manufacture the precast reinforced concrete box culverts. 1.4.1.6 Regulatory authority — an authority which is empowered by statute to exercise jurisdiction over the construction of a culvert in the relevant location or region. 1.4.1.7 Specified—stated in writing in any document (including orders, drawings or specifications, or both) which forms a part, or the whole of the contract between the purchaser and the manufacturer. 1.4.2



Technical



1.4.2.1 Batch — a group of culvert units, link or base slabs of the same class complying with a particular design and produced under uniform conditions during a given production period, by the same process. 1.4.2.2 Bed zone—the area between the foundation and the underside of the culvert (see Figure 1.1). 1.4.2.3 Concentrated sampling — sampling of prototype units concentrated in time and location of manufacture. 1.4.2.4 Cover—distance between the outside of the reinforcing steel and the nearest permanent surface of the member excluding any surface finish. 1.4.2.5 Critical loading — loading with increasing critical load(s) until the ultimate load capacity is reached (following proportional loading to a specified level). 1.4.2.6 Critical load(s) —the load(s) with the greatest load factor(s) in accordance with the relevant design load combination.



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1.4.2.7 Culvert—a single cell or a multiple cell structure, and associated link slabs and base slabs. 1.4.2.8 Culvert cell—a complete conduit made up of a number of units placed end-to-end. 1.4.2.9 Culvert unit—a single unit, whether integral or a combination of U-shaped sections with a slab. 1.4.2.10 Dispersed sampling — sampling of prototype units taken evenly from at least five batches, either manufactured at five different locations or drawn evenly from one location at intervals of not less than two months. 1.4.2.11



Failure load — a load applied to determine the ultimate load capacity.



1.4.2.12



Fill—one or more of the following:



(a)



Backfill or embankment fill—material placed over the overlay zone or the side zone for the purpose of refilling a trench or creating an embankment (see Figure 1.1).



(b)



Ordinary fill—material obtained from excavation of the trench or elsewhere and containing no more than 20% by mass of aggregates with a size between 75 mm and 150 mm and none larger than 150 mm.



(c)



Selected fill—material obtained from excavation of the trench or elsewhere with a particle size not greater than 75 mm, and which conforms with the following soil classes, as defined in AS 1726:



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AS 1597.2 — 1996



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(i)



SC . . . . . . . . . clayed sands with fines of low plasticity.



(ii)



SP . . . . . . . . . poorly graded sands.



(iii)



SW . . . . . . . . well-graded sand.



(iv)



GC . . . . . . . . clayey gravels with fines of low plasticity.



(v)



GW . . . . . . . . well-graded sand and gravel mixtures with little or no plastic fines.



(vi)



GP . . . . . . . . poorly graded sand and gravel mixtures with little or no plastic fines.



1.4.2.13 Foundation —naturally occurring or replaced material beneath the bed zone (see Figure 1.1).



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1.4.2.14 Height of fill—height of fill over the culvert, or the vertical distance between the surface of the fill or pavement to the location concerned.



FIGURE 1.1



FILL AND CULVERT SUPPORT TERMS



1.4.2.15 Load Class — culvert strength classification system designated by the height of fill over the culvert, in metres, followed by the design live load description, hyphenated. 1.4.2.16 Mean strength enhancement factor —the factor determined from prototype strength parameters to account for differences between the mean prototype strengths and the mean strengths of units produced in routine production. COPYRIGHT



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AS 1597.2 — 1996



1.4.2.17 Monolithic — a culvert shall be defined as being monolithic if at least two corner joints of the cell are fully rigid connections. 1.4.2.18 Overlay zone—the area extending directly above the top of the culvert, which has a depth of not less than 150 mm (see Figure 1.1). 1.4.2.19 Proof load — a load applied to a predetermined level to demonstrate adequate performance. 1.4.2.20 Proportional loading —the loading of prototype units increased uniformly up to failure whilst maintaining the proportionality of loads in accordance with the relevant design load combination. 1.4.2.21 Regular culvert —an inverted ‘U’-shaped culvert with symmetrical cross-section and horizontal crown. 1.4.2.22 Side zones—the areas bounded by the outside of the culvert leg, the top of the bed zone, the level of the top of the culvert and for a lateral extent as shown in Figure 1.1. 1.4.2.23 Size Class—culvert size classification system designated by one hundredth the nominal span of the culvert unit in millimetres and one hundredth the nominal height of the culvert unit in millimetres. 1.4.2.24 Standard culvert —a regular culvert of size class given in Table 2.3(A) and (B) and load class given in Clause 1.8.3. 1.5 NOTATION Every symbol used in this Standard is listed below. Symbols which occur in more than one clause are defined below and used in the various clauses without further reference. Symbols which occur only in one clause are defined in that clause as well as being listed and defined below.



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Unless a contrary intention appears, the symbols used in the Standard shall have the meanings ascribed to them below, with respect to the structure or condition to which a clause is applied. Ag



=



gross concrete area of the section in flexure



As



=



the cross-sectional area of reinforcement



b



=



the width of a cross-section



BLF



=



the basic proof load factor



dem



=



the measured effective depth of tension reinforcement



den



=



the specified nominal effective depth



dv



=



effective depth of reinforcement for shear



D



=



the measured thickness



Dm



=



the measured thickness at a cross-section



Dn



=



the specified nominal thickness



ew



=



effective width for consideration of moment and shear effects under live load



Fi



=



characteristic unit load effect magnitude for the i th failure



fc′



=



the characteristic compressive cylinder strength of concrete at 28 d



fcm



=



the mean value of the relevant concrete cylinders compressive strengths measured at the time of prototype testing



fcm,b



=



mean value of concrete cylinder compressive strengths measured during routine manufacturing tests in relation to a particular batch of units



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AS 1597.2 — 1996



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fsy



=



specified minimum yield strength of reinforcement in accordance with AS 3600



fym



=



the mean value of the measured steel reinforcement yield stress



H



=



height of fill over culvert or height of fill at the location concerned



H 1, H 2, H3



=



horizontal basic test loads for prototype testing



Hr



=



vertical distance from top of rail to the location concerned



hz



=



total height of the fill taken from the ground finished surface to the base of the culvert



I



=



dynamic load allowance factor



ID



=



the density index



K1



=



fym / (1.2 fsy )



K2



=



(D m / Dn ), or (d em / d en), whichever is the greater



K3



=



(f cm / fc′ )0.5, or alternatively



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(f cm / fcm,b )0.5 in relation to design strength for a particular batch kL



=



coefficient of earth pressure for live load



ko



=



coefficient of earth pressure at rest



k oc



=



over consolidated coefficient of earth pressure



Ku



=



the neutral axis parameter, being the ratio, at ultimate strength and under any combination of bending and compression, of the depth to the neutral axis from the extreme compressive fibre



L



=



span of culvert unit, link or base slab



LF



=



proof load factor



Lb



=



one metre plus the depth of ballast and fill under the sleepers but no greater than the axle spacing



Li



=



characteristic load magnitude for the i th specimen in a sample of size n, or alternatively strength ratio for the ith failure in a sample size n



Ls



=



length of sleeper



mL



=



the sample mean peak load



mSF



=



mean strength enhancement factor



n



=



the sample size



PI



=



plasticity index



Rd



=



the design load capacity



Rn



=



nominal ultimate strength



R ni



=



nominal ultimate strength corresponding to F i



RD



=



the dry density ratio



RF



=



the minimum value of the reinforcement ratio ρ D /ρi



SF



=



strength enhancement factor



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AS 1597.2 — 1996



SL



=



dispersal length of strip load, measured parallel to the direction of the span of the culvert



U1



=



maximum positive moment, crown



U2



=



maximum negative moment, crown



U3



=



maximum positive moment, knee



U4



=



maximum negative moment, knee



U5



=



maximum positive moment, leg



U6



=



maximum negative moment, leg



U7



=



maximum shear, crown



U8



=



maximum shear, leg



VL



=



coefficient of variation



V uc



=



ultimate shear strength



V 1, V2 , V3



=



vertical basic test loads for prototype testing



W



=



gravity force per unit volume of fill material



W CH



=



construction load induced horizontal earth pressure



W CV



=



construction load induced vertical earth pressure



W DC



=



dead load of unit



W FH



=



horizontal earth pressure due to fill



W FV



=



vertical earth pressure due to fill



W LH



=



live load induced horizontal earth pressure



W LL



=



railway axle load



W LV



=



live load induced vertical earth pressure



W PH



=



HLP320 load induced horizontal earth pressure



W PV



=



HLP320 load induced vertical earth pressure



W RH



=



railway live load induced horizontal earth pressure



W RV



=



railway live load induced vertical earth pressure



ρ



=



a flexural steel ratio



ρD



=



the flexural reinforcement ratio for the specified design



ρi



=



the flexural reinforcement ratio for the prototype test specimen



θ



=



angle of internal friction of soil



φ



=



strength reduction factor



φ est



=



estimate of the test capacity reduction factor



φT



=



test capacity reduction factor



νb



=



characteristic ultimate shear stress at the cross-section



1.6



USE OF ALTERNATIVE MATERIALS OR METHODS



1.6.1 General This Standard shall not be interpreted so as to prevent the use of materials or methods of design or construction not specifically referred to herein, provided that such materials or methods can be shown to meet the intention of this Standard. NOTE: Alternative materials or methods should be approved by the regulatory authority. COPYRIGHT



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1.6.2 Existing structures Where the strength or serviceability of an existing structure is to be evaluated, the general principles of this Standard may be applied. The actual properties of the materials in the structure shall be used. 1.7 TYPES OF CULVERTS The types of culverts covered by this Standard are specified in Table 1.1. TABLE



1.1



TYPES OF CULVERTS Type of culvert



Description



U-shape (Invert & lid)



A monolithic U-shaped section forming the invert and the two walls, and a separate top slab.



Inverted U-shape (Crown unit & base)



A monolithic inverted U-shaped section forming the deck slab and the two walls, and a separate base slab



One piece



An integral hollow rectangle forming the top slab, the two walls and the base slab



Link slab (Crown & base with link)



Schematic illustration



A single slab supported on adjacent units or structures



NO TES: 1 U-shape and inverted U-shape are sometimes supplied without the lid slab or base slab, respectively. The information should be supplied by the purchaser (see Appendix A).



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



2 See also Figure 3.1 for culvert configuration.



1.8



CLASSIFICATION



1.8.1 General Culvert units, link and base slabs shall be classified on the basis of the criteria for size and load given in Clauses 1.8.2 and 1.8.3, respectively. NOTE: A Size Class 1815 and Load Class 2-A unit is referenced as Class 1815/2-A.



1.8.2 Size Class Culvert units shall be classified by the numerical value of one hundredth the nominal span of the unit followed by the numerical value of one hundredth the nominal height, in millimetres. Standard Size Class for culvert units, link and base slabs are given in Tables 2.3(A) and 2.3(B). NOTES: 1



A nominal 1800 mm span and nominal 1500 mm height culvert unit is referenced as Size Class 1815.



2



A nominal 1800 mm span link slab is referenced as Size Class 1800.



1.8.3



Load Class



1.8.3.1 General Culvert units, link and base slabs shall be classified by the height of fill over the culvert, in metres, generally followed by the design live load description, hyphenated. COPYRIGHT



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AS 1597.2 — 1996



Roadway and railway culvert, link and base slab units may be classified up to Class 10— (A, for roadway, or R, for railway, as appropriate; for example, 1515/6-A, 3636/5R). Railway culvert, link and base slab units designed for other than M270 loading are designated by the load description, i.e. 5 m vertically from the top of rail to the top of the unit and design load M220 designated Class 5— RM220. 1.8.3.2 Load Class for roadway For standard culvert units, link slabs and base slabs under roadway live loading, the Load Class is designated as follows: (a)



Class 2-A Subjected to fill material vertically over the culvert, from zero up to and including 2.0 m and AUSTROADS vehicle live loadings.



(b)



Class 3-A Subjected to fill material vertically over the culvert, greater than 2.0 m, up to and including 3.0 m and AUSTROADS vehicle live loadings.



(c)



Class 4-A Subjected to fill material vertically over the culvert greater than 3.0 m, up to and including 4 m.



(d)



Class 5-A Subjected to fill material vertically over the culvert greater than 4.0 m, up to and including 5 m.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



1.8.3.3 Load Class for railway Standard culvert units, link slabs and base slabs units subjected to railway M270 live loading shall be designated as Class R. Basic test loads for railway culverts have not been included in the given tables since fatigue considerations may be required.



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S E C T I O N



2 M AT E R I A L S , M A N U F AC T U R E A N D D IM E NS I O N I N G



2.1 SCOPE This Section specifies the materials to be used, method of manufacture and dimensional requirements to be observed in the manufacture of culverts designed in accordance with either Section 3 or Section 4. 2.2 FORMWORK Forms shall be designed and constructed to provide the shapes, dimensions and surface finish in the end product. The forms shall be mortar-tight, braced and tied together so that they maintain position and shape during placing and compaction of concrete. 2.3



REINFORCEMENT



2.3.1 General Reinforcement shall comply with AS 1302, AS 1303, AS 1304 and AS 3600, as applicable, except as required below. 2.3.2 Welding Fixing welds may be used for grid assembly and shall not substantially reduce the cross-section of the reinforcing steel nor adversely affect its strength. Welding shall be kept to a minimum necessary to locate reinforcement during erection and placement of concrete. Reinforcing wire to AS 1303 may be machine resistance welded. 2.4 2.4.1



CONCRETE MATERIALS Cement



Cement shall be materials complying with AS 3972.



2.4.2 Supplementary cementitious materials Supplementary cementitious materials shall comply with the applicable part of AS 3582.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



2.4.3 Aggregates Aggregates shall comply with AS 2758.1. Any additional requirements that may, according to that Standard, need to be separately specified for a particular usage or application are as follows: (a)



Maximum water absorption— for fine aggregates . . . . . . . . . . . . . . . . . 1.5%; and for coarse aggregates . . . . . . . . . . . . . . . 2.5%.



(b)



Durability— minimum wet strength . . . . . . . . . . . . . 100 kN; and maximum wet/dry strength variation . . . . . 25%.



Lightweight aggregates and non-ferrous metallurgical slag aggregates shall not be used in concrete for culvert units. 2.4.4



Water



Water shall comply with the requirements of AS 1379.



2.4.5 Admixtures Chemical admixtures shall comply with AS 1478. Chemical admixtures shall not contain nitrates, significant chlorides or other strongly ionized salts unless it can be shown that they do not adversely affect durability. 2.4.6 Restriction on chemical content The materials shall not contain acid-soluble chloride or sulfate salts in excess of the values given in Table 2.1. Other strongly ionized salts, such as nitrates, shall not be added to concrete unless it can be shown that they do not adversely affect durability. 2.5



SPECIFICATION AND MANUFAC TURE OF CONCRETE



2.5.1



Strength grade



Minimum strength grade shall be N40.



2.5.2



Manufacture Manufacture of concrete shall comply with AS 1379. COPYRIGHT



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TABLE



AS 1597.2 — 1996



2.1



MAXIMUM VALUES OF ACID-SOLUBLE CHLORIDE AND SULFATE ION CONTENT IN CONCRETE AS CAST Maximum acid-soluble chloride ion content (kg/m 3)



Maximum acid-soluble sulfate ion content percent (by mass of cement)



Concrete cured at ambient temperature



0.8



5.0



Steam-cured concrete



0.8



4.0



Condition



2.6 HANDLING, PLACING AND FINISHING OF CONCRETE The handling, placing and finishing of concrete shall comply with the requirements of AS 3600. 2.7



CURING



2.7.1 General Concrete shall be cured, using one or a combination of the methods described in Clauses 2.7.2 to 2.7.4. The concrete shall be protected from moisture loss until the commencement of the curing and shall continue until the concrete reaches the strength set out in Table 2.2. The concrete strength for checking the adequacy of curing shall be determined by test specimens cured with and in the same manner as the concrete unit. The concrete unit shall not be completely stripped from all forms or handled off the base forms until the compressive strength reaches 15 MPa. Curing shall not be interrupted for more than 30 min until the strength specified in Table 2.2 is reached. TABLE



2.2



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



CURING FOR CONCRETE Exposure classification (Refer to AS 3600)



Required concrete compressive strength at completion of curing MPa



A1, A2, B1



20



B2 C



25 32



NO TE: For exposure classification U, curing should be agreed upon between the purchaser and manufacturer.



2.7.2 Moist curing Concrete shall be kept continuously moist and the concrete maintained at a temperature above 5°C. 2.7.3 Membrane curing Curing compounds may be used in lieu of moist curing, if authorized by the purchaser. Curing compounds shall be applied to all exposed concrete surfaces to manufacturer’s specifications. The concrete shall be maintained at a temperature above 5°C. 2.7.4 Accelerated curing Accelerated curing shall be carried out by low pressure steam curing in accordance with Appendix C. Other methods may be used with the prior approval of the purchaser.



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AS 1597.2 — 1996



2.8 JOINTS specified. 2.9



16



The end joint between units shall be a butt joint unless otherwise



DIMENSIONS



2.9.1 Internal dimensions Preferred internal dimensions for culvert units, link and base slabs are listed in Tables 2.3(A) and 2.3(B) and shown in Figure 2.1. 2.9.2 Length The preferred nominal length of culvert units, link and base slabs shall be either 1200 mm or 2400 mm.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



FIGURE 2.1



CULVERT AND LINK SLAB TERMS



2.10 COVER TO REINFORCEMENT Required cover for manufacture in rigid forms and intense compaction shall be as per Table 2.4.



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TABLE



AS 1597.2 — 1996



2.3(A)



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



PREFERRED INTERNAL DIMENSIONS — CULVERT UNITS Size class



Nominal span mm



Nominal height mm



1 509



1 500



900



1 512



1 500



1 200



1 515



1 500



1 500



1 812



1 800



1 200



1 815



1 800



1 500



1 818



1 800



1 800



2 412



2 400



1 200



2 415



2 400



1 500



2 418



2 400



1 800



2 424



2 400



2 400



3 012



3 000



1 200



3 018



3 000



1 800



3 024



3 000



2 400



3 030



3 000



3 000



3 612



3 600



1 200



3 618



3 600



1 800



3 624



3 600



2 400



3 630



3 600



3 000



3 636



3 600



3 600



4 218



4 200



1 800



4 224



4 200



2 400



4 230



4 200



3 000



4 236



4 200



3 600



4 242



4 200



4 200



NO TES: 1



The Size Class is designated by one hundredth the nominal span of the culvert unit in millimetres and one hundredth the nominal height of the culvert unit in millimetres (1800 span by 1500 height is Size Class 1815).



2



Other size culverts, including larger sizes, can be made to a specific order.



3



Actual size should be checked with manufacturers.



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TABLE



2.3(B)



PREFERRED DIMENSIONS — LINK AND BASE SLABS Size Class



Nominal span mm



1 500 1 800



1 500 1 800



2 400



2 400



3 000



3 000



3 600



3 600



4 200



4 200



NO TES: 1



The Size Class is designated by the nominal span of the link slab in millimetres (1800 span is Size Class 1800).



2



Other size link slabs, including larger sizes, can be made to specific order.



3



Actual size should manufacturers.



TABLE



be



checked



with



2.4



REQUIRED COVER



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



Exposure classification (see AS 3600)



Required cover, mm Characteristic strength (f c′) 40 MPa



50 MPa



60 MPa



A1, A2, B1



25



25



25



B2



40



30



25



C



—



45



30



NO TES: 1 Nibs and spacers for reinforcement are excluded from all the above cover requirements. 2 Table 2.4 is based on AUSTROA DS Bridge design code for 100 years life span and for no negative tolerance. 3 Other types of manufacture should refer to AU STRO AD S Bridge design code for guidance. 4 For installation in non-aggressive ground environment a minimum exposure classification B1 is recommended.



2.11



MEASUREMENT OF DIMENSIONS



2.11.1 General The dimensions of a culvert unit, link slab and base slab shall be determined in accordance with Clauses 2.11.2 to 2.11.5 at the place of manufacture. 2.11.2 Size dimensions The internal size dimensions of span and height of culvert units and span of link slabs or base slabs shall be determined by taking measurements at 200 mm from each end and at the midpoint of the length of the unit. The size dimension for span and height of culvert units and link slabs or base slabs shall be taken as the mean of the three values. COPYRIGHT



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AS 1597.2 — 1996



2.11.3 Thickness The thickness of the culvert unit crown, link slab or base slab shall be determined by taking measurements at the end and midpoint of the span at locations 200 mm from each end and at the midpoint of the length of the unit. The thickness shall be taken as the mean of the nine values. The thickness of culvert unit legs shall be measured 200 mm up from the base of the legs and at the junction of the inside corner haunch or crown and the top of the legs, and 200 mm from each end and midpoint of the length. The leg thickness at each horizontal plane shall be taken as the mean of the three values. 2.11.4 Cover Appendix D.



The concrete cover to reinforcement shall be measured as described in



2.11.5 Length The length of a culvert unit, link slab or base slab shall be determined by taking measurements at the ends and at the midpoint of the span. The length dimension shall be the mean of the three values. 2.12



TOLERANCES



2.12.1 General The tolerance on a measured dimension shall be the difference between the manufacturer’s specified dimension and the value determined in accordance with Clause 2.11. The tolerance on the basic shape shall be applied to the measurement at the location. 2.12.2



Dimension tolerances



2.12.2.1 Size dimensions The size dimension of span and height of culvert units and span of a link slab or base slab shall not differ from the manufacturer’s stated dimension by more than ±10 mm. 2.12.2.2 Thickness The thickness of the culvert unit, link slab or base slab shall not differ from the manufacturer’s stated dimension by more than +8 mm or -5 mm. 2.12.2.3 Cover The actual concrete cover to reinforcement shall not differ from the specified cover by more than +10 mm or -0 mm.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



2.12.2.4 Length The length of the culvert unit, link slab or base slab shall not differ from the manufacturer’s stated dimension by more than ±15 mm. 2.12.3



Basic shape tolerances



2.12.3.1 Ends When tested by means of a tri-square, the end faces of the culvert unit, link slab or base slab at any location shall be square within ±4 mm when measured across the unit section thickness. 2.12.3.2 Verticality With the base of the culvert unit horizontal, the vertical side faces of the culvert unit legs as stated by the manufacturer and the culvert unit vertical end faces shall not deviate from the vertical at any location by more than ±20 mm for the entire overall height dimension of the culvert unit. 2.12.3.3 Squareness The plan diagonals of the culvert unit crown, link slab or base slab and the side elevation diagonals of each culvert unit leg shall not differ by more than ±20 mm. 2.13 PROVISION FOR LIFTING Provision shall be made for lifting and handling the culvert unit, link or base slab. The lifting points provided and incorporated into the unit shall be designed in accordance with Clause 3.2.5. 2.14 WORKMANSHIP AND FINISH The concrete shall be dense and substantially free from chipped edges, laitance, surface roughness, fractures, cracks, dents and bulges.



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2.15



20



DEFECTS



2.15.1 General Defects in culvert units, link and base slabs shall be classified by type, in accordance with Clause 2.15.2, and the acceptability or otherwise of units containing a particular type of defect shall be determined in accordance with Clause 2.15.3. Surface craze cracks (usually of irregular pattern) and hairline cracks (cracks just visible to the naked eye) not extending through the culvert thickness shall not be classed as defects. 2.15.2



Types



Defects are classified as the following types:



(a)



Type 1—clearly visible cracks not extending through the culvert thickness and whose width, as determined in accordance with Appendix E, is not greater than 0.15 mm.



(b)



Type 2—cracks not extending through the culvert thickness and whose width, as determined in accordance with Appendix E, is greater than 0.15 mm and less than 0.3 mm.



(c)



Type 3—cracks extending through the culvert thickness or cracks whose width, as determined in accordance with Appendix E, is greater than 0.3 mm.



(d)



Type 4—dents, bulges, chips and spalls of a depth or height not more than one half of the cover and extending in any direction not more than 100 mm from its centroid. Surface blowholes shall not exceed 10 mm in depth and 20 mm in diameter. NOTE: Where dents, bulges, chips and spalls extend to greater than 100 mm, they should be subject to negotiation between the purchaser and the manufacturer.



(e)



Type 5—dents, bulges, chips and spalls as for Type 4 but of a depth or height between one-half and three-quarters of the cover. Surface blowholes larger than Type 4 and bony patches of depth not more than the cover and extending in any direction not more than 150 mm from its centroid. NOTE: Any defects larger than the above should be subject to negotiation between the purchaser and manufacturer.



Visible inclusions of foreign matter, with a total surface area less than 0.1% of the culvert surface area, either inside or outside. No individual inclusion shall be greater than 750 mm2 in area. Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



(f)



Type 6—inclusion of foreign matter, in particular material of organic origin greater than Type 5.



2.15.3 Acceptability The acceptability or otherwise of culvert units, link and base slabs with defects, arising from manufacture or handling, shall be determined in accordance with Table 2.5. TABLE



2.5



ACCEPTABILITY OF DEFECTS Defect type



Acceptability



1



Acceptable



2



Acceptable after repair



3



Acceptable after repair and serviceability load testing



4



Acceptable



5



Acceptable after repair



6



Not acceptable



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AS 1597.2 — 1996



2.16 MARKING The following markings shall be clearly stencilled with indelible ink or embossed into the concrete on the interior of each culvert unit near the top on the underside of a link slab and on the top surface of a base slab: (a)



Date and place of manufacture.



(b)



Manufacturer’s name or registered trade mark.



(c)



The Size Class and Load Class (when specified) of the unit.



(d)



The maximum mass of the unit, in kilograms rounded up to the nearest 100 kg.



NOTE: Manufacturers making a statement of compliance with this Australian Standard on a product, packaging or promotional material related to that product are advised to ensure that such compliance is capable of being verified.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



2.17 FINISHING AND REPAIRS Finishing and repairs to culvert units, link or base slabs shall be carried out using materials having a tensile and bond strength not less than that of the concrete in the unit.



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22



S E C T I O N



3.1



3



D ES I G N R E Q U I R E M EN TS P R O C ED U R E S



A N D



GENERAL



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



3.1.1 Scope This Section specifies design requirements and procedures for precast reinforced concrete box culverts, including base and link slabs. Relevant culvert configurations include — (a)



single cell (see Figure 3.1(a));



(b)



multi-cell with units placed side-by-side (see Figure 3.1(b)); and



(c)



culvert units in a link slab arrangement (see Figure 3.1(c)).



FIGURE 3.1 TYPICAL CULVERT CONFIGURATIONS (SHOWING INVERTED U CULVERT UNITS)



3.1.2 General design requirements Culverts shall be designed to satisfy requirements for stability, strength, serviceability, durability and other relevant design requirements in accordance with the procedures given in this section, and taking account of the installed configuration. Installed configurations shall be such that connections between bearing surfaces (between culverts, base slabs and link slabs) shall act as pinned connections, without sliding.



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AS 1597.2 — 1996



Design for strength or serviceability shall be based on the design loads and design load combinations specified in Clause 3.2 and a choice between — (a)



load-effect analysis and theoretical strength and serviceability calculations in accordance with Clauses 3.3 and 3.4;



(b)



load testing in accordance with Section 4; or



(c)



a combination of Items (a) and (b).



The design strengths shall be not less than the design load effects for each relevant load combination for ultimate strength limit states. Serviceability acceptance criteria shall be satisfied for the relevant load combinations for serviceability limit states. Flexural crack widths should not exceed the values defined in Table 3.1 for service loads. TABLE



3.1



RECOMMENDED MAXIMUM CRACK WIDTHS AT SERVICE LOADS Recommended maximum crack widths Cover (mm) Service load applied



Service load removed



35



0.50



0.30



Fatigue shall be considered where relevant and, if significant, shall be taken into account in the design of the structure. NOTE: Generally, railway culvert units and link slabs should be considered for fatigue effects.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



3.2



DESIGN LOADS



3.2.1



Dead loads



3.2.1.1 General Values of dead loads due to the culvert unit weight (W DC) and the vertical earth pressure (W FV) shall be estimated and used in design. NOTE: In the absence of specific information, the gravity forces and densities given in Appendix F may be used for estimating dead load.



3.2.1.2



Vertical earth pressure



Vertical earth pressure shall be calculated as follows:



W FV = WH



. . . 3(1)



where W FV = vertical earth pressure due to fill, in kilonewtons per square metre (kN/m 2) W



= gravity force per unit volume of fill material, in kilonewtons per cubic metre (kN/m 3)



H



= height of fill over culvert, in metres (m)



3.2.1.3 Horizontal earth pressure due to compacted fill In the absence of information specific to a site, the horizontal earth pressure for a compacted fill which is free draining may be calculated as follows: W FH = k ocWH



. . . 3(2)



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AS 1597.2 — 1996



24



where W FH = horizontal earth pressure due to fill, in kilopascals (kPa) k oc



= over consolidated coefficient of earth pressure = k o [2 + (1.0 − H)/h z]



W



= gravity force per unit volume of fill material, in kilonewtons per cubic metre (kN/m 3)



H



= height of fill at the location concerned, in metres (m)



and where ko



= coefficient of earth pressure at rest = (1 − sinθ)



hz



= total height of the fill taken from the ground finished surface to the base of the culvert



θ



= angle of internal friction of soil



NOTE: For free draining granular fill material, W may be taken as 20 kN/m 3 and k o may be taken as 0.5 for both serviceability and ultimate limit state.



3.2.2



Traffic loads for culverts under roadways



3.2.2.1 General Culverts under roadways shall be designed to resist vertical and horizontal forces due to standard traffic loads, heavy load platform and construction traffic loads. Soil pressures due to traffic loads shall be amplified by the dynamic load allowance factor given in Clause 3.2.2.5. 3.2.2.2 Standard traffic loads Standard traffic loads shall be defined by the wheel loadings and spacings of the W7 wheel and T44 truck loadings specified in the AUSTROADS Bridge Design Code. Standard traffic loads shall be applied to the culvert at its final fill height or for the applicable range of fill heights, when required.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



3.2.2.3 Construction traffic loads Unless otherwise specified, construction traffic loads and their effects W CV and W CH shall be defined by the wheel loadings and spacings of the W7 or T44 truck loadings, specified in the AUSTROADS Bridge Design Code (as for standard traffic loads). Construction traffic loads shall be applied to the culvert at a fill height of 400 mm, or the final fill height if that is less than 400 mm. 3.2.2.4 Heavy load platform The heavy load platform (HLP) shall be the HLP320 loading specified in the AUSTROADS Bridge Design Code and shall be applied to culverts at its final fill height. 3.2.2.5



Dynamic load allowance



3.2.2.5.1 Application The standard traffic load, HLP load and construction traffic load shall be increased to account for the interaction of moving vehicles and the culvert. The dynamic load allowance applies to both the serviceability and ultimate limit states. 3.2.2.5.2 Dynamic load allowance factor calculated as follows:



The dynamic load allowance factor I shall be



(a) For standard traffic loads: I =



. . . 3(3)



(b) For HLP load, construction traffic loads and all values of H: I = 1.1



. . . 3(4)



where I = dynamic load allowance factor H = height of fill at the location concerned, in metres (m)



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3.2.2.6



AS 1597.2 — 1996



Vertical traffic loading



3.2.2.6.1 General For roadways, live loads shall be dispersed through the fill from the imprint of the load to a rectangular area. The sides of the rectangle shall be determined by increasing the imprint size by 0.5 H to a depth of 0.2 m and then by 1.2 times the increase in depth from 0.2 m. Where surcharges from two or more loads overlap, the total load may be considered to be evenly dispersed over the total surcharged area. Standard traffic live loads may be deemed to comply with the above dispersal for depths greater than 400 mm fill by using the requirements of Clause 3.2.2.6.2. 3.2.2.6.2 Vertical loads due to standard traffic loadings The vertical loads due to W7/T44 traffic loading for fill not less than 400 mm may be modelled as an equivalent strip load as described below. The equivalent strip load is a single movable uniform strip load of width ‘SL’ which is orientated so that ‘SL’ dimension is parallel to the direction of the span of the culvert, with the strip movement in the span direction. The vertical earth pressure under the strip load shall be calculated as follows: . . . 3(5)



W LV = where W LV = live load induced vertical earth pressure, in kilopascals (kPa) SL



= dispersal length of strip load, measured parallel to the direction of the span of the culvert, in metres (m) = H + 1.4 or = 2H + 0.4, whichever is less



and where H



= height of fill over the culvert, in metres (m)



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



3.2.2.7 Horizontal traffic loading The horizontal traffic loadings may be determined using the following equations for the horizontal soil pressures acting on a culvert leg (dependent on depth H). (a)



Peak horizontal soil pressures for standard traffic load is given by the equation: W LH =



for H ≥ 0.4



W LH = 136 kLH



for H < 0.4



. . . 3(6)



or where W LH = roadway live load induced horizontal earth pressure, in kilopascals (kPa) kL



= coefficient of earth pressure for live load, taken to be equal to 0.5



H



= height of fill at the location concerned, in metres (m)



The peak pressures are developed along a vertical line directly below the centre of the standard traffic wheel loads, and the pressures linearly reduce to zero at 600 mm from the vertical centre-line. (b)



Uniform horizontal soil pressures for Heavy Load Platform (HLP320) is given by the equation: W PH = WLH + 4



for H ≥ 0.4



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. . . 3(7)



AS 1597.2 — 1996



26



or W PH = (136 k L + 10)H



for H < 0.4,



where W PH = HLP load induced horizontal earth pressure, in kilopascals (kPa) (c)



An alternative to Items (a) and (b) above is given by the equation: W LH = kL W LV or W PH = kL W PV where W LV or WPV are calculated by load dispersal through the fill in accordance with Clause 3.2.2.6.1.



3.2.3



Live loads for culverts under railways



3.2.3.1 General For railway loading, the lateral dispersal through the ballast and fill from the underside of the sleeper shall be at the linear rate of 0.5 times the height from the underside of the sleeper. 3.2.3.2 Vertical load Unless otherwise specified by the relevant regulatory authority, railway load for each track shall be the ‘M270’ track loading where the M270 loading is the loading configuration of the Metric Cooper M250 railway loading defined in the ANZRC Railway Bridge Design Manual increased by the ratio 270/250. The railway live load induced vertical earth pressure is given by the equation: . . . 3(8)



W RV = where



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



(L s + H r − 0.3) ≤ 4.0 for multiple tracks W RV



= railway live load induced vertical earth pressure, in kilopascals (kPa)



W LL



= railway axle load, in kilonewtons (kN)



Ls



= length of sleeper, in metres (m)



Hr



= vertical distance from top of rail to the location concerned, in metres (m)



Lb



= one metre plus the depth of ballast and fill under the sleepers (but not greater than the axle spacing), in metres (m)



The vertical live load induced earth pressure obtained shall be adjusted by the dynamic load allowance factor as determined in accordance with Clause 3.2.3.4. 3.2.3.3 Horizontal load The live load induced horizontal earth pressure acting uniformly along the culvert length shall be calculated from the following equation, except that for Hr ≤ 0.7m, W RH shall be as calculated for Hr = 0.7m and then reduced linearly to zero at Hr = 0.3m. W RH shall be adjusted by the dynamic load allowance factor given in Clause 3.2.3.4 for the height of fill at the location being considered. For induced earth pressure due to railway loading: W RH = k LWRV



. . . 3(9)



where kL



= coefficient of earth pressure for railway load, taken to be equal to 0.5



W RH = railway live load induced horizontal earth pressure, in kilopascals (kPa) W RV = railway live load induced vertical earth pressure, in kilopascals (kPa)



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3.2.3.4



AS 1597.2 — 1996



Dynamic load allowance



3.2.3.4.1 Application The railway live load shall be increased to account for the interaction of the moving load and the culvert. The dynamic load allowance applies to both the serviceability and ultimate limit states. 3.2.3.4.2 Dynamic load allowance factor calculated as follows: I



= 1.64 - 0.20(H r - 0.3) ≥ 1.0



I



= dynamic load allowance factor



The dynamic load allowance factor I shall be . . . 3(10)



where Hr = vertical distance from top of rail to the location concerned, in metres 3.2.4



Load combinations



3.2.4.1 Load combinations for stability and ultimate strength limit states Unless otherwise specified by the purchaser, culverts shall be designed to resist the loads applicable for the final and intermediate stages of construction and for the culvert cell configuration, with the load factors set out in Tables 3.2 and 3.3. TABLE



3.2



FACTORS FOR VERTICAL LOADS Load



Load factor



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WDC



1.0



WFV



1.4 or 0.9



WLV



2.0 or 0.0



WCV



1.5 or 0.0



WPV



1.5 or 0.0



WRV



1.6 or 0.0



TABLE



3.3



FACTORS FOR HORIZONTAL LOADS Asymmetric loading Load



Symmetric loading on both sides of culvert



WFH



On one side of culvert



On opposite side of culvert



0.7 or 1.4



1.4



0.7



W LH



2.0 or 0.0



—



—



WCH



1.5 or 0.0



—



—



WPH



1.5 or 0.0



—



—



WRH



1.6 or 0.0



—



—



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AS 1597.2 — 1996



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In determining the critical load combinations it should be taken that — (a)



the asymmetrically factored earth pressure due to fill is not applied concurrently with any other horizontal earth pressure loading;



(b)



vertical earth pressure due to live load can be applied with or without concurrent horizontal earth pressure due to live load; and



(c)



horizontal earth pressure due to live load can be applied with or without concurrent vertical earth pressure due to live load.



3.2.4.2 Load combinations for serviceability limit states For the purpose of assessing specified serviceability limit states, the culvert shall be checked for relevant load combinations and cell configurations, with the load factors set out in Table 3.4. TABLE



3.4



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LOAD FACTORS Load



Load factor



WDC WCV WFV



1.0 1.0 or 0.0 1.0



WLV WPV WRV



1.0 or 0.0 1.0 or 0.0 1.0 or 0.0



WCH WFH W LH



1.0 or 0.0 1.0 1.0 or 0.0



WPH WRH



1.0 or 0.0 1.0 or 0.0



3.2.5 Handling and transport loads Culvert units and bracing systems (where necessary) shall be designed for a horizontal braking or handling acceleration of 0.5 g (gravitational acceleration) on each leg. This shall be applied in the direction of the span of the unit. Culvert units, link and basic slabs shall be designed for lifting in accordance with the specified lifting points provided. Lifting point inserts and attachments shall be designed for ultimate forces of not less than four times the maximum calculated static lifting force applied during transport and handling. 3.3



LOAD EFFECT ANALYSIS



3.3.1 General Load effect analysis of culverts shall be based on accepted principles and assumptions as detailed in the AUSTROADS Bridge Design Code, ANZRC Railway Bridge Design Manual and AS 3600 as appropriate. 3.3.2 Restrained sidesway Where appropriate, for a culvert installed to meet the requirements of Section 6, sidesway of the culvert may be considered to be restrained by bearing against the soil.



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AS 1597.2 — 1996



3.3.3 Effective width of culvert for W7/T44 wheel load For a W7/T44 wheel load applied directly to the top surface of a culvert, the effects shall be considered as being distributed within the top, bottom and legs of the unit over a distance perpendicular to the span direction of the culvert unit given by the following equations: e w = 0.86 + 0.03L for serviceability load combinations (or e w may be calculated by more rigorous analysis)



. . . 3(11)



e w = 1.22 but not greater than the unit length, for ultimate load combinations



. . . 3(12)



where e w = effective width for consideration of moment and shear effects under live load, in metres (m) L = span of the culvert unit, link or base slab in metres (m) (see Figure 2.1) 3.4



THEORETICAL STRENGTH AND SERVICEABILITY CALCULATIONS



3.4.1



Strength



3.4.1.1 General The theoretical design strength φR u shall be determined in accordance with AS 3600 unless otherwise specified herein. 3.4.1.2 Strength reduction factor For culverts manufactured with a manufacturing quality assurance system, enhanced strength reduction factors, determined in accordance with Section 4, may be used to determine the design ultimate strengths for flexure and shear based on the calculated nominal ultimate strengths. 3.4.1.3 Shear strength The ultimate shear strength of any section may be calculated from the equation below. The corresponding critical cross-section for shear shall be taken as shown in Figure 3.2: V uc = v bbd v



. . . 3(13)



where V uc = ultimate shear strength, in newtons (N) Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



vb



= characteristic ultimate shear stress at the cross-section, in megapascals (MPa) =



b



= width of section in millimetres (mm)



dv



= effective depth taken as the distance from the extreme compression fibre of the concrete to the centroid of the flexural tensile reinforcement, in millimetres (mm) = characteristic compressive cylinder strength of the concrete at 28 days, in megapascals (MPa)



Where a slab is haunched, the critical section for shear shall be considered in both the haunch and the slab as shown in Figure 3.2. 3.4.2 Serviceability Serviceability parameters shall be calculated in accordance with AS 3600, where appropriate. 3.4.3 Fatigue For fatigue, the maximum calculated stress range in reinforcing steel, using the load combinations given in Clause 3.2.4, shall not exceed 195 MPa in straight bars, nor 90 MPa at bends and at welds in bars, but excluding fixing welds. NOTE: The stress limits for reinforcing steel will generally also limit concrete compression stresses in units to acceptable limits to avoid fatigue failure in the compression concrete.



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AS 1597.2 — 1996



3.5



30



REINFORCEMENT DETAILING



3.5.1 General Unless otherwise given in this Section, detailing of reinforcement including spacing, anchorage, splicing, hooks, extensions of reinforcement at supports and the termination of reinforcement between supports shall comply with the requirements of the AUSTROADS Bridge Design Code, the ANZRC Railway Bridge Design Manual or AS 3600, as appropriate. 3.5.2 Minimum flexural reinforcement The area of the flexural reinforcement in the span direction shall be not less than 0.002 A g. 3.5.3 Distribution reinforcement Distribution reinforcement in culvert unit crown and link slabs is reinforcement placed at the level, or immediately adjacent to the flexural reinforcement and perpendicular to it. The distribution reinforcement shall be placed as follows: (a)



For zero fill over and live loadings Distribution reinforcement in the bottom face of crown or link slab shall be 15% of the calculated flexural reinforcement per metre necessary at the midspan with a minimum at any location in the culvert unit crown and legs or link slab and base slab, as for Clause 3.5.3(b).



(b)



Minimum reinforcement Distribution reinforcement shall be provided in the crown and legs of the culvert unit, link slab and base slab and shall be a minimum of 150 mm2 per metre measured along the main flexural reinforcement, with a maximum bar spacing of 300 mm.



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3.5.4 Crack control The centre-to-centre spacing of bars required for strength in bending shall not exceed the lesser of 1.5 D or 300 mm. For the purpose of this Clause, bars with a diameter less than half the diameter of the largest bar in the cross-section shall be ignored.



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FIGURE 3.2 CRITICAL SHEAR SECTIONS COPYRIGHT



AS 1597.2 — 1996



AS 1597.2 — 1996



32



S E C T I O N



4



L O AD



T E S TI N G F O R



D E S I G N



4.1 SCOPE This Section sets out special requirements for design based on load testing. Requirements are included for prototype proof load tests for serviceability and strength, prototype failure load tests for empirical assessments of design strengths, and failure load tests to calibrate strength prediction models. 4.2



GENERAL REQUIREMENTS



4.2.1 General Designs based on load testing shall satisfy all requirements specified in Sections to 1 to 3 except for those requirements in Clause 3.4 which are alternative requirements to those satisfied in accordance with the special requirements for load testing. NOTE: Appendix G sets out flow charts to assist in the interpretation of Clauses 4.6 and 4.7.



4.2.2 Prototype proof load tests for serviceability Prototype proof load tests for serviceability shall be carried out in accordance with Clause 4.5. 4.2.3 Prototype proof load tests for strength Prototype proof load tests for strength shall be carried out in accordance with Clause 4.6. 4.2.4 Prototype failure load tests for empirical assessments of design strengths Prototype failure load tests for empirical assessments of design strengths shall be carried out in accordance with Clause 4.7.1. 4.2.5 Failure load tests for calibration of a strength prediction model Failure load tests for calibration of a strength prediction model shall be carried out in accordance with Clause 4.7.2. 4.3



TEST SPECIMENS



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4.3.1 General Test specimens shall be manufactured in accordance with normal procedures for routine production, and they shall be representative of normal variations of dimensions and material properties. The reinforcement of each specimen shall not exceed the specified nominal amount, and the placement of the reinforcement shall satisfy normal manufacturing tolerances. 4.3.2 Prototype test specimens Prototype test specimens for a particular prototype design shall be nominally identical, except that the specified amount (but not the extent) of flexural reinforcement may be varied. If prototype test specimens are not identically reinforced, the test results shall be assessed in accordance with Clause 4.6.2.2 for proof loading or Clause 4.7.1.2.2 for failure loading. At least 5 test specimens are required for design based on failure load tests. 4.3.3 Test specimens to calibrate a theoretical strength prediction model At least five test specimens are required to calibrate a theoretical strength prediction model. They shall be representative of the range of culvert units, link and base slabs for which the model is to be calibrated. 4.3.4



Properties of test specimens



4.3.4.1 General specimens:



Tests shall be carried out to assess the following properties of the test



(a)



Yield strength of reinforcement.



(b)



Concrete strength.



(c)



Dimensions.



(d)



Cover to reinforcement.



(e)



Defects. COPYRIGHT



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AS 1597.2 — 1996



4.3.4.2 Yield strength of reinforcement One sample of each bar size and type of reinforcement used for the manufacture of each test specimen shall be tested for yield strength in accordance with AS 1302, AS 1303 or AS 1304, as appropriate. 4.3.4.3 Concrete strength A minimum of eight concrete compression cylinders shall be made and tested in accordance with AS 1012.1, AS 1012.8 and AS 1012.9 from the concrete pour during the manufacture of each culvert unit, link or base slab test specimen. Among the eight or more concrete compression cylinders made, a minimum of six cylinders shall be cured with the test specimen and the remaining two or more cylinders shall be standard cured for testing at 28 days in accordance with AS 1012.9. At the time of stripping of the test specimen from the moulding forms, two of the six or more cylinders cured with the specimen shall be tested for strength and the remaining four or more cylinders shall be held for testing to determine fcm at the time when the test specimen is load tested. 4.3.4.4 Dimensions Each culvert unit, link or base slab test specimen, shall be measured to check dimensional accuracy in relation to the dimensional tolerances specified in Clause 2.12, and to assess relevant strength parameters as required in accordance with Clause 4.3.4. 4.3.4.5 Cover to reinforcement Each culvert unit, link or base slab test specimen shall be inspected for reinforcement cover by the method specified in Appendix D. Cover shall be measured to an accuracy of ±1 mm. 4.3.4.6 Defects Each culvert unit, link or base slab test specimen shall be inspected for defects in accordance with Clause 2.15. Defects of Types 2, 3 and 5 shall be repaired prior to load testing. Test specimens with Type 3 or Type 6 defects should not be used for prototype tests or tests to calibrate a theoretical strength prediction model.



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4.3.5



Strength enhancement factors



4.3.5.1 General Strength enhancement factors shall be determined from measured values of relevant strength enhancement parameters related to the steel reinforcement yield stresses, the concrete strengths, the culvert unit, link or base slab depth (thicknesses) and the effective depths of the reinforcement. The strength enhancement factors for a test specimen shall be based on the weighted average values of the strength enhancement parameters noted below, measured in relation to the critical section(s) for the relevant strength limit states. Strength enhancement factors for strength limit states of flexure and shear shall be determined as follows: SF = K 1 × K 2 , for strength limit states of flexure



. . . 4(1)



SF = K 2 × K 3 , for strength limit states of shear



. . . 4(2)



where K 1 = f ym/(1.2fsy ) K 2 = (Dm/D n ) or K 2 = (dem /den ), whichever is the greater K 3 = (fcm /fc′)0.5 or alternatively K 3 = (fcm /fcm,b )0.5 in relation to the design strength of a particular batch of units. and where (dem /den )



= weighted average value of (d em/den ) at critical sections where dem is the measured effective depth of tension reinforcement and den is the specified nominal effective depth



(Dm/D n)



= weighted average value of (Dm/Dn ) at critical sections where Dm is the measured depth (thickness) and D n is the specified nominal depth COPYRIGHT



AS 1597.2 — 1996



34



fym



= weighted average value of measured steel reinforcement yield stresses



fsy



= specified minimum yield strength of the reinforcement in accordance with AS 3600



fcm



= mean value of the relevant concrete cylinder compressive strengths measured at the time of prototype testing



fcm,b



= mean value of concrete cylinder compressive strengths measured during routine manufacturing tests in relation to a particular batch of units



fc′



= specified characteristic concrete cylinder compressive strength at 28 days



For each prototype test specimen, strength enhancement factors shall be determined for all relevant strength limit states and related test load conditions. 4.3.5.2 Mean strength enhancement factors for failure load tests For each group of specimens used for failure load tests, mean strength enhancement factors shall be determined for each load test condition and each relevant strength limit state, based on the strength enhancement factors SF for all prototype test specimens in the group. The mean strength enhancement factor m SF for a strength limit state related to a particular load test condition shall be determined as follows: mSF =



. . . 4(3)



where SF i = relevant strength enhancement factor for the ith failure in a sample of size n and where n



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



4.4



= total number of relevant failures for that load condition



TEST LOADS



4.4.1 General Test loads shall be applied to simulate the range of design load effects associated with load combinations specified in Clause 4.5.1, Clause 4.6.1, Clause 4.7.1 or Clause 4.7.2, based on the design loads specified in Clause 3.2.4. The test loads shall be applied in sequences representative of anticipated design loads, using proportional loading in accordance with Clause 4.4.2 or critical loading (for failure load tests only), in accordance with Clause 4.4.3, as appropriate. The test loads shall simulate the effects of variable load positions. For each test load combination, a characteristic load shall be selected to characterize the magnitude of the loads. For critical loading, the characteristic load shall be a critical load. The maximum rate of loading shall not exceed 1% of the maximum applied load per second. The loads shall be applied, measured and recorded to an accuracy of ±3%. 4.4.2 Proportional loading Loads shall be applied so as to maintain proportionality of loads in accordance with the relevant design load combination.



the



4.4.3 Critical loading Loads shall be increased using proportional loading up to a level corresponding to the specified design loading, multiplied by SF/φ est where SF is the relevant strength enhancement factor (Clause 4.3.4) and φ est is an estimate of the test capacity reduction factor φ T in accordance with Clause 4.7.3. The critical loads shall then be increased until the maximum load carrying capacity is attained. If there is more than one critical load (with a common load factor), then the critical loads shall be increased in proportion. COPYRIGHT



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AS 1597.2 — 1996



If the vertical live load is the critical load, an increasing vertical load (V2 for a standard culvert) shall be applied at the centre of the crown to produce a failure. If a flexural failure is obtained, then the test loads shall be removed and an increasing vertical load (V 1 for a standard culvert) shall be applied at the critical shear section to obtain a shear failure near the opening haunch. 4.4.4 Test loads for regular culverts including standard culverts For a regular culvert, horizontal test loads H1 , H2 and H 3, and vertical test loads V 1, V 2 and V3 shall be applied, as required, in the positions shown in Figures 4.1(A) and 4.1(B) or Figure 4.2, as appropriate. The horizontal test loads shall be applied as uniformly distributed loads acting on strips 200 mm wide, extending along the full length of the culvert unit. The vertical test loads representing fill loads may be applied as uniformly distributed loads acting on strips 200 mm wide, extending along the full length of the culvert unit, link or base slab. Simulated wheel loads shall be applied as uniformly distributed loads acting on strips 200 mm wide and the length of the loaded strip associated with each wheel load shall not exceed the length of the culvert unit or link slab, or the length of the wheel load where there is less than 400 mm fill over the top of the unit or slab. Simulated traffic loads shall be positioned with a wheel load at an edge. 4.4.5 Test apparatus The test apparatus for regular (and standard) units shall be capable of applying the required test loads as indicated in Figures 4.1(A) and 4.1(B) for culvert units or Figure 4.2 for link and base slabs in accordance with the relevant requirements in Appendix H. 4.5



PROTOTYPE PROOF LOAD TESTS FOR SERVICEABILITY



4.5.1 General Serviceability test loads shall simulate the effects of the serviceability design load combinations specified in Clause 3.2.4.2. Serviceability test loads shall include loads to simulate expected flexural actions, with and without vertical loads on the culvert crown and with or without sway, as appropriate.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



For standard culverts and link slabs, serviceability test loads are given in Appendix I. 4.5.2 Serviceability indicators Quantitative serviceability indicators should be measured at the serviceability test load, so that statistics of the relevant indicators can be estimated. 4.5.3 Crack width Crack widths in regular (and standard) units under serviceability test loads should be measured by the method given in Appendix E using the procedure set out in Appendix H. The measured crack width in any prototype test unit under serviceability test crack load and after removal of the load should not exceed the appropriate value given in Table 5.1.



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AS 1597.2 — 1996



36



DIMENSIONS IN MILLIMETRES



FIGURE 4.1(A) SCHEMATIC ARRANGEMENT OF PROTOTYPE ‘REGULAR’ CULVERT UNITS— LOAD TESTING COPYRIGHT



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AS 1597.2 — 1996



DIMENSIONS IN MILLIMETRES



FIGURE 4.1(B) SCHEMATIC ARRANGEMENT OF PROTOTYPE ‘STANDARD’ CULVERT UNITS — LOAD TESTING



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AS 1597.2 — 1996



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DIMENSIONS IN MILLIMETRES



FIGURE 4.2 SCHEMATIC ARRANGEMENT OF PROTOTYPE ‘REGULAR’ AND ‘STANDARD’ ‘LINK’ OR BASE SLABS — LOAD TESTING



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4.6



AS 1597.2 — 1996



PROTOTYPE PROOF LOAD TESTS FOR ULTIMATE STRENGTH



4.6.1 Prototype proof loads for ultimate strength Prototype proof load combinations for ultimate strengths shall simulate the effects of specified design load combinations for ultimate strength limit states (specified in Clause 3.2.4.1) multiplied by proof load factors LF such that — LF = SF × BLF, if SF > 1, or LF = BLF, otherwise,



. . . 4(4) . . . 4(5)



where LF = proof load factor SF = the relevant strength enhancement factor (Clause 4.3.4) BLF = the appropriate basic proof load factor specified in Table 4.1 (related to sample size) TABLE



4.1



BASIC PROOF LOAD FACTORS



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



Number of nominally identical prototype units tested



Basic proof load factor (BLF) Shear



Flexure



1



2.48



1.83



2



2.12



1.65



3



1.94



1.55



4



1.82



1.48



5



1.73



1.44



6



1.66



1.40



8



1.56



1.34



10



1.48



1.29



20



1.27



1.17



50



1.03



1.02



100



0.88



0.92



The basic proof load factor for flexure given in Table 4.1 is valid for flexural steel ratios ρ = (A s/bd en) not greater than the maximum values specified in Table 4.2. TABLE



4.2



MAXIMUM FLEXURAL STEEL CONTENT (%) f sy



Concrete Strength fc′ (MPa) 40



50



60



400



2.6



3.0



3.2



500



2.1



2.4



2.6



NO TE: These flexure steel ratios are based on a K u value of 0.4.



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AS 1597.2 — 1996



40



Where the flexural steel percentage exceeds the maximum value specified in Table 4.2, the basic proof load factor for shear given in Table 4.1 shall also be used for flexure. For standard culverts, basic test loads equivalent to the specified design load combinations are given in Appendix J, and prototype proof loads for ultimate strength can be obtained by applying the appropriate proof load factors LF (based on the basic proof load factors for flexure, for loading types U1-U6 and the basic proof load factors for shear, for loading types U7-U8). 4.6.2



Ultimate strength acceptance criteria based on prototype proof load tests



4.6.2.1 General For a particular prototype design with a specified amount of reinforcement, the ultimate strength design requirements of this Standard shall be deemed to be satisfied for design loads corresponding to the lowest values (for all the prototype test specimens) of the peak test loads divided by the appropriate proof load factors LF determined in Clause 4.6.1. 4.6.2.2 Specimens with non-identical reinforcement In order to assess a specified prototype design based on prototype proof load tests on prototype test specimens with non-identical reinforcement, the peak test loads shall be taken to be the equivalent peak test loads for the specified design, adjusted in accordance with the specified reinforcement. For each prototype test specimen i and each test load condition, a reinforcement factor RF shall be defined as the minimum value of the reinforcement ratio ρ D/ρ i at any critical section for that load condition, where ρ D represents a flexural reinforcement ratio for the specified design and ρ i represents the corresponding reinforcement ratio for the prototype test specimen i. The equivalent peak test loads for the specified design shall be taken to be the actual peak test loads for the prototype test specimen i multiplied by the corresponding reinforcement factors RF. Equivalent peak test loads associated with reinforcement factors RF greater than 1 shall be accepted as valid, if and only if, they do not increase the design strengths. Actual peak test loads (taking RF equal to 1) may be used in lieu of the equivalent peak test loads associated with reinforcement factors RF greater than 1.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



4.7



FAILURE LOAD TESTS



4.7.1



Prototype failure load tests for empirical assessments of design strengths



4.7.1.1 General Prototype failure load tests for empirical assessments of design strengths (without theoretical strength calculations) shall be carried out on a minimum of five prototype test specimens for each relevant load combination or observed mode of failure. More than one failure and more than one mode of failure may be obtained from each test specimen, based on failures at different critical sections. Details of the failure modes and failure loads shall be recorded so that the relevant load capacities can be assessed. Loads shall be applied to produce failures, using proportional or critical loading based on relevant design load combinations specified in Clause 3.2.4.1. 4.7.1.2



Failure load statistics



4.7.1.2.1 General Failure loads shall be taken to be the measured peak loads associated with ultimate limit states of structural behaviour. For each failure (related to a failure index i) a characteristic failure load magnitude L i shall be determined (in relation to a characteristic unit load-combination vector, if appropriate). For proportional loading at failure, for each failure load combination and relevant mode of failure, a sample mean peak load mL and coefficient of variation V L shall be determined from the characteristic failure load magnitudes Li (with a minimum sample size of five for each failure mode). COPYRIGHT



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AS 1597.2 — 1996



For critical loading at failure, the coefficient of variation V L shall be determined from the characteristic failure load magnitudes L i as above, but the sample mean peak load m L shall be taken to be the mean of the peak values of the characteristic load, evaluated at the limits of proportional loading: mL =



. . . 4(6)



where Li = characteristic load magnitude for the ith failure in a sample of size n V L = σ L/m L and where σL = 4.7.1.2.2 Specimens with non-identical reinforcement For prototype failure load tests on specimens with non-identical reinforcement, the failure loads and limits of proportional loadings shall be taken to be the equivalent failure loads for a specified design, adjusted in accordance with the specified reinforcement. For each prototype test specimen i and each test load condition, a reinforcement factor RF shall be defined as the minimum value of the reinforcement ratio ρ D/ρ i at any critical section for that load condition, where ρ D represents a flexural reinforcement ratio for the specified design and ρ i represents the corresponding reinforcement ratio for the prototype test specimen i. The equivalent loads for the specified design shall be taken to be the actual loads for the prototype test specimen i multiplied by the corresponding reinforcement factors RF.



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



Equivalent loads associated with reinforcement factors RF greater than 1 shall be accepted as valid if and only if they do not increase the design strengths. Actual loads (taking RF equal to 1) may be used in lieu of the equivalent loads associated with reinforcement factors RF greater than 1. 4.7.1.3 Design load capacity The design load capacity R d for each load combination and failure mode shall be given by the product of the test capacity reduction factor φ T in accordance with Clause 4.7.3 and the sample mean peak load magnitude (mL), divided by the relevant mean strength enhancement factor m SF for the sample determined in accordance with Clause 4.3.4.2 as shown in the following equation: R d = φ T × m L/mSF



. . . 4(7)



If more than one failure mode has been observed, then the design load capacity R d shall be the smallest of the design load capacities for the various failure modes. The design load capacity Rd may be used as the basis for design acceptance (in lieu of theoretical design strength calculations) for the specified prototype design. 4.7.2



Failure load tests for calibration of a strength prediction model



4.7.2.1 General Failure load tests to calibrate a strength prediction model shall be carried out on a minimum of five test specimens with relevant failures produced under test load conditions corresponding to anticipated design load combinations. More than one failure and more than one mode of failure may be obtained from each test specimen, based on failures at different critical sections. Details of the failure modes and failure loads shall be recorded so that the relevant load effects can be assessed.



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Test loads shall be applied to produce failures, using proportional or critical loading based on the anticipated design load combinations appropriate to the application of the strength prediction model. 4.7.2.2 Selection of strength prediction models Strength prediction models shall be selected from those permitted in accordance with Section 3 for strength assessments by calculation. 4.7.2.3 Determination of failure load effects Failure load effects relevant to a selected strength prediction model shall be determined with an accuracy of ±5% at the critical sections (in accordance with the strength prediction model), based on appropriate measurements of applied loads and reactions (if necessary). 4.7.2.4 Strength statistics Failure load effects relevant to a strength prediction model shall be determined at critical sections (in accordance with the strength prediction model). For each relevant failure, a characteristic failure load effect magnitude F i (for the ith failure) shall be determined (in relation to a characteristic unit load-effect vector, if appropriate). The strength prediction model shall be used to determine the nominal ultimate strength R ni corresponding to each value of F i (in relation to a characteristic unit load effect vector, if appropriate). The strength ratio Li shall be determined, relating the actual strength F i to the nominal ultimate strength Rni as follows: Li = F i/R ni



. . . 4(8)



mL =



. . . 4(9)



where Li = strength ratio for the ith failure in a sample of size n VL = σ L / m L



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



and where σL = 4.7.2.5 Design strength The design strength R d for a calibrated strength prediction model shall be given by the nominal ultimate strength R n multiplied by a calibrated design capacity reduction factor φ d as follows: Rd = φd R n



. . . 4(10)



where φ d = φ T (mL/mSF ) and where φT



= the relevant test capacity reduction factor determined from the statistics of the strength ratio L in accordance with Clause 4.7.3



mL = the mean strength ratio mSF = the relevant mean strength enhancement Clause 4.3.4.2)



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factor (in accordance



with



43



AS 1597.2 — 1996



The design load capacity R d may be used as the basis for design acceptance (in lieu of theoretical design strength calculations in accordance with Section 3) for the design of culverts with strength parameters within the range associated with the test results used to calibrate the strength prediction formula. 4.7.3 Test capacity reduction factor A test capacity reduction factor φT (related to the sample mean m L) shall be determined from Figure 4.3 or Figure 4.4, accounting for concentrated or dispersed sampling, the sample size n and the coefficient of variation V L of the test results.



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Dispersed sampling denotes sampling that is dispersed with respect to manufacturing locations (involving samples drawn evenly from at least five locations) or time of manufacture (involving samples drawn evenly from at least five batches of prototypes manufactured from separate batches of materials and manufactured at intervals of not less than two months). Concentrated sampling denotes sampling that cannot be classified as dispersed due to a concentration in time and location of manufacture.



FIGURE 4.3



TEST CAPACITY REDUCTION FACTOR FOR CONCENTRATED SAMPLING



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AS 1597.2 — 1996



TEST CAPACITY REDUCTION FACTOR FOR DISPERSED SAMPLING



Accessed by UNIVERSITY OF SOUTHERN QUEENSLAND on 18 Mar 2009



FIGURE 4.4



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S E C T I O N



5



R O U T I N E S A MP L I N G T E S T I N G



AS 1597.2 — 1996



A N D



5.1 GENERAL Routine sampling and testing shall be carried out in accordance with this Section to ensure that culvert units, link and base slabs produced to a particular design comply with the specific requirements of this Standard. Each culvert unit, link or base slab shall be inspected for visual defects (see Clause 2.15). 5.2



REQUIRED TESTS



5.2.1 General During the period of manufacture of a batch of culvert units, link or base slabs to a particular design, representative samples shall be randomly selected from the concrete used and the samples tested for strength in accordance with Clause 5.2.2. Culvert units, link and base slabs designed to meet the requirements of Clause 3.4.2 shall not be subjected to routine crack serviceability test load. A random sample of culvert units, link or base slabs shall also be taken from the batch and subjected to the following tests: (a)



Dimensional accuracy (see Clause 5.2.3).



(b)



Cover to reinforcement (see Clause 5.2.3).



(c)



Crack serviceability test load (see Clause 5.2.4).



NOTE: Reinforcement supplied in accordance with AS 1302, AS 1303 or AS 1304, as appropriate need not be subjected to routine sampling and testing.



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5.2.2 Concrete strength A minimum of two concrete compression cylinders shall be taken at not greater than 10 h of continuous manufacture of a culvert unit, link or base slab batch and tested for strength. The concrete compression cylinders shall be made in accordance with AS 1012.1 and AS 1012.8 and subsequently tested in accordance with AS 1012.9. Curing of concrete compression cylinders shall be carried out in accordance with AS 1012.8. Concrete compression cylinders shall be cured initially with the product. As soon as is practicable after a period of 18 h from moulding, the test cylinders shall be placed under standard moist-curing conditions. The time between moulding and entry into standard moist-curing condition shall not exceed 36 h. 5.2.3 Dimensional accuracy, and cover to reinforcement A random sample of one unit taken from a batch of not more than 50 culvert units, link or base slabs produced to a particular design for Load Class and Size Class shall be inspected for dimensional accuracy and cover to reinforcement by the methods specified in Clause 2.11. 5.2.4 Crack serviceability test load A random sample of culvert units, link or base slabs shall be taken from a batch of culvert units, link or base slabs manufactured to a particular design and load tested in accordance with Appendix H. Each sample shall be subjected to the appropriate test crack load for its corresponding Size Class and Load Class and shall not develop a crack size greater than the relevant test crack given in Table 5.1 and measured in accordance with Appendix E. For standard units, the test crack load values are given in Appendix I. Upon removal of the test load, no crack in the culvert unit, link or base slab shall be greater in size than that given in Table 5.1.



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AS 1597.2 — 1996



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TABLE



5.1



THICKNESS OF FEELER GAUGE FOR CRACK WIDTH DETERMINATION Thickness of feeler gauge (mm)



Specified cover (mm)



Culvert loaded



Culvert unloaded



25



0.25



0.15



>25 ≤35



0.35



0.20



>35



0.50



0.30



5.3 SAMPLING FOR LOAD TESTING The sampling plans and procedures for the assessment of each quality parameter shall comply with the requirements of AS 1199 for a double sampling plan and an acceptable quality level (AQL) not greater than 6.5%. These requirements shall be deemed to be satisfied if the sampling procedures given in Appendix K are carried out. 5.4 COMPLIANCE Each sample unit in a batch of culvert units, link or base slabs of a particular Size Class and Load Class shall comply with the requirements for — (a)



concrete strength, if each of the concrete compression cylinders in Clause 5.2.1 meet the requirements for specified concrete strength ( fc′) or mean compressive strength in accordance with Clause 4.3.3.2, as appropriate;



(b)



dimensional accuracy, and cover to reinforcement, if the sample unit in Clause 5.2.2 meets the specified requirements; and



(c)



for prototype design culvert units, link and base slabs only, crack serviceability test load, if each of the sample units in Clause 5.2.3 meets the specified requirements.



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If one or more of the tests for concrete strength, dimensional accuracy, cover to reinforcements and crack serviceability test load (for prototype design only) in the sample group is less than the specified requirements, the batch shall be deemed to be nonconforming. 5.5



ACCEPTANCE If a batch of culvert units, link or base slabs is deemed to—



(a)



comply with all design requirements, in accordance with Clause 5.4, the batch shall be accepted without further testing; or



(b)



if nonconforming, the purchaser may — (i)



reject the batch;



(ii)



accept the batch after further testing as agreed upon between the purchaser and the manufacturer; or



(iii)



accept the batch as being of lower quality than the specified quality, and any acceptance being without prejudice because of noncompliance with the specified requirements.



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6



AS 1597.2 — 1996



I N S T AL L AT I O N



6.1 SCOPE This Section sets out the requirements for installation of precast culverts, including excavation, foundation preparation, placing of units, compaction and backfilling. Installation is described for all types of culverts shown in Table 1.1 and includes situations where the base slab is either in situ concrete or precast concrete. 6.2 EXCAVATION Excavation width should provide a minimum gap of 150 mm between culvert walls and trench walls (or any wall support system). Depth of excavation will depend on type of base slab (in situ concrete or precast concrete) and foundation conditions encountered. The foundation should be carefully trimmed to the required depth and gradient making allowance for thickness of bed zone material, if required. Local hard or soft areas of the trench bottom which could cause uneven settlement, should be excavated and replaced with compacted selected fill. Alternatively, foundations may be further excavated until a firm foundation of uniform bearing value is obtained. 6.3 FOUNDATION PREPARATION In situ concrete base slabs should be cast either on rock foundations or on soil foundations which can support service loads. Selected fill given in Clause 1.4.2.12(c) may comply. Precast base slabs, U-shaped culvert units and one piece culvert units should be supported on a bed zone of selected fill of depth not less than 150 mm. This selected fill shall have a particle size distribution, determined in accordance with AS 1289.C6.1, preferably falling within the limits given in Table 6.1 with the fraction passing the 0.075 mm sieve being material of low plasticity, as defined in AS 1726. Bed zone material, shall be compacted to a dry density ratio of 90% or a density index of 60% in accordance with the requirements specified in Clause 6.5. TABLE



6.1



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GRADING LIMITS FOR SELECTED FILL IN BED ZONE Sieve size mm



Mass passing %



19.0



100



2.36



100 to 50



0.60



90 to 20



0.30



60 to 10



0.15



25 to 0



0.075*



10 to 0



* Material passing a 0.075 mm sieve should have low plasticity with a PI ≤10.



6.4 PLACING PRECAST UNITS Precast concrete units shall be placed on a base slab only after concrete test specimens cast and cured with the base slab pour have attained a minimum compressive strength of 20 MPa. Base slabs, whether in situ or precast concrete, shall have rebates or upstands of sufficient structural integrity to enable transfer of horizontal loads and to locate the inverted U-shaped culvert units. COPYRIGHT



AS 1597.2 — 1996



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Before placing the top slab on a U-shaped culvert unit, an inverted U-shaped culvert on a base slab or a link slab supported on adjacent inverted U-shaped culvert units, the surface bearing area of the support shall be cleaned of dust and grit and covered with a layer of stiff cement mortar mix. The precast unit shall be placed in position before the mortar has set to ensure uniform bearing between surfaces. NOTE: The layer should be not less than 5 mm thick after the precast unit has been placed in position.



After placing the inverted U-shaped culverts any gap between the inside bottom of the culvert leg and the side of the base recess or upstand shall be filled with sand and cement mortar. Sand-cement mortar, or equivalent, shall also be applied to — (a)



dowel holes in a link slab, where provided; and



(b)



in the gap between the walls of adjacent culvert units in multiple installations for a minimum depth equal to the crown thickness.



All grouting in the gap between adjacent units in multiple installations shall be hard set and be at least 4 h old prior to the commencement of side backfill. All mortar used during installation shall have a maximum 3:1 ratio of sand and cement by volume. Ends of the individual units, which make up a culvert, shall be aligned so that they act as a unit under load. 6.5 COMPACTION Special attention shall be given during installation of culverts to compaction of the material under and around culverts to ensure that the assumed support is achieved.



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Where a percentage is specified, it shall be measured by one of the following parameters as applicable: (a)



Cohesive soils The dry density ratio (R D) is determined in accordance with AS 1289.5.4.1 based on the field dry density in accordance with AS 1289.5.3.2 and the maximum dry density in accordance with AS 1289.5.1.1.



(b)



Cohesionless soils The density index (I D ) is determined in accordance with AS 1289.E6.1, based on the maximum and minimum dry densities in accordance with AS 1289.E5.1 and the field dry density in accordance with AS 1289.5.3.2 or AS 1289.E3.5.



6.6 BACKFILLING Side zone material shall be selected fill having a particle size distribution, determined in accordance with AS 1289.C6.1, falling within the limits given in Table 6.2 or alternatively, cement slurry fill with a compressive strength (f c′) in the range 3 MPa to 5 MPa may be used. Materials which are marginally outside these grading limits may be used in combination with other materials if construction techniques are used which improve ease and stability of compaction. In embankment installation conditions, this side zone material shall extend out to a width equal to one-third the height of the culvert (see Figure 1.1). Side zone material shall be placed up to the level of the top of the culvert, whilst maintaining a maximum difference of 600 mm between compacted material levels on each side of the culvert. Side zone material shall be compacted to a dry density ratio of 90% or a density index of 60% in accordance with the requirements specified in Clause 6.5. Overlay zone material shall be compacted ordinary fill or compacted fill of finer grading.



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TABLE



AS 1597.2 — 1996



6.2



GRADING LIMITS FOR SELECTED FILL IN SIDE ZONES



*



Sieve size mm



Mass passing %



75.0 9.5 2.36 0.60 0.075*



100 100 to 50 100 to 30 50 to 15 25 to 0



Material passing 0.075 mm sieve should have low plasticity with a PI ≤15.



6.7 CONSTRUCTION LOADS ON CULVERTS In accordance with Clause 3.2.2.2, construction traffic shall be limited to vehicles with axle loadings no heavier than vehicles normally permitted on public roads except where — (a)



the culvert is designed for a specific heavy construction vehicle (i.e. scraper); or



(b)



the height of fill over the culvert exceeds the minimum depth of cover as specified in Table 6.3.



In the case of vibrating rollers, the gross load, including static load and dynamic load, shall be taken as the axle load for determining the required depth of cover over the culvert as given in Table 6.3. The first 400 mm of fill over the culvert should be placed with a pneumatic tyred grader with axle loads less than 10 tonne. TABLE



6.3



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MINIMUM HEIGHTS OF FILL FOR CONSTRUCTION VEHICLE AXLE LOADS Axle load (including 10% impact allowance) (see Note) kN



Design fill height m



140



250



500



640



0 to 2



0.4 m



1.4 m



2.0 m



—



>2 to