1、Designation: C1786 17Standard Specification forSegmental Precast Reinforced Concrete Box Sections forCulverts, Storm Drains, and Sewers Designed According toAASHTO LRFD1This standard is issued under the fixed designation C1786; the number immediately following the designation indicates the year ofor
2、iginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers precast reinforced concretebox sect
3、ions comprised of separate segments that once prop-erly field assembled make the final structure. These structuresare intended to be used for the construction of culverts and forthe conveyance of storm water, industrial wastes and sewage.NOTE 1This specification is primarily a manufacturing and purc
4、has-ing specification. However, box culverts manufactured to this standard areintended to meet the design requirements of the AASHTO LRFD BridgeDesign Specifications, and as such, design guidance is included inAppendix X1.NOTE 2The successful performance of this product depends upon theproper select
5、ion of the box section, bedding, backfill, and care that theinstallation conforms to the construction specifications. The purchaser ofthe precast reinforced concrete box sections specified herein is cautionedthat proper correlation of the loading conditions and the field requirementswith the box sec
6、tion specified, and provision for inspection at theconstruction site, are required.1.2 The values stated in inch-pound units are to be regardedas standard. No other units of measurement are included in thisstandard.1.3 This international standard was developed in accor-dance with internationally rec
7、ognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A615/A615M Specific
8、ation for Deformed and Plain Carbon-Steel Bars for Concrete ReinforcementA706/A706M Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete ReinforcementA1064/A1064M Specification for Carbon-Steel Wire andWelded Wire Reinforcement, Plain and Deformed, forConcreteC33/C33M Specification
9、 for Concrete AggregatesC150/C150M Specification for Portland CementC260/C260M Specification for Air-Entraining Admixturesfor ConcreteC309 Specification for Liquid Membrane-Forming Com-pounds for Curing ConcreteC494/C494M Specification for Chemical Admixtures forConcreteC497 Test Methods for Concret
10、e Pipe, Manhole Sections, orTileC595/C595M Specification for Blended Hydraulic CementsC618 Specification for Coal Fly Ash and Raw or CalcinedNatural Pozzolan for Use in ConcreteC822 Terminology Relating to Concrete Pipe and RelatedProductsC989/C989M Specification for Slag Cement for Use inConcrete a
11、nd MortarsC1017/C1017M Specification for Chemical Admixtures forUse in Producing Flowing ConcreteC1116/C1116M Specification for Fiber-Reinforced ConcreteC1602/C1602M Specification for Mixing Water Used in theProduction of Hydraulic Cement Concrete2.2 AASHTO Standards:3AASHTO LRFD Bridge Design Speci
12、ficationsAASHTO LRFD Bridge Construction Specifications2.3 ACI Standards:4ACI 318 Building Code Requirements for Structural Con-crete3. Terminology3.1 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee C13 onConcrete Pipe and is the direct re
13、sponsibility of Subcommittee C13.07 onAcceptance Specifications and Precast Concrete Box Sections.Current edition approved Oct. 1, 2017. Published October 2017. Originallyapproved in 2014. Las previous edition approved in 2016 as C1786 16. DOI:10.1520/C178617.2For referenced ASTM standards, visit th
14、e ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Ca
15、pitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.4Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.concrete.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Uni
16、ted StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barrier
17、s to Trade (TBT) Committee.13.1.1 box sectionthe completed box culvert unit with allsegments adjoined (see Fig. 1 for configuration options).3.1.2 box segmentthe individual piece (top slab, bottomslab, or three-sided structure) that gets adjoined to other piecesto complete the final box section3.2 D
18、efinitionsFor definitions of terms relating to concretebox culvert sections not found above, see Terminology C822.4. Basis of Acceptance4.1 Acceptability of the box sections produced in accor-dance with this standard shall be determined by the results ofthe concrete compressive strength tests descri
19、bed in Section10, by the material requirements described in Section 5, and byinspection of the finished box sections by the owner or theirdesignee.NOTE 3The box culvert structure itself is not complete until it is fullyassembled in the field. Field assembly is not included in this specification.Howe
20、ver, a final field inspection is recommended before the box culvertis considered fit for duty.5. Material5.1 Reinforced ConcreteThe reinforced concrete shallconsist of cementitious materials, mineral aggregates, admix-tures if used, and water, in which steel has been embedded insuch a manner that th
21、e steel and concrete act together.5.2 Cementitious Materials:5.2.1 CementCement shall conform to the requirementsfor portland cement of Specification C150/C150M or shall beportland blast-furnace slag cement, portland-limestone cement,or portland-pozzolan cement conforming to the requirementsof Speci
22、fication C595/C595M, except that the pozzolan con-stituent in the Type IP portland-pozzolan cement shall be flyash.5.2.2 Fly AshFly ash shall conform to the requirements ofSpecification C618, Class F or Class C.5.2.3 Slag CementSlag cement shall conform to the re-quirements of Grade 100 or 120 of Sp
23、ecification C989/C989M.5.2.4 Allowable Combinations of Cementitious MaterialsThe combination of cementitious materials used in concreteshall be one of the following:5.2.4.1 Portland cement only,5.2.4.2 Portland blast-furnace slag cement only,5.2.4.3 Portland-pozzolan cement only,5.2.4.4 Portland-lim
24、estone cement only,5.2.4.5 A combination of portland cement or portland-limestone cement and fly ash,5.2.4.6 A combination of portland cement or portland-limestone cement and slag cement, or5.2.4.7 A combination of portland cement or portland-limestone cement, slag cement, and fly ash, or5.2.4.8 A c
25、ombination of portland-pozzolan cement and flyash.5.3 AggregatesAggregates shall conform to SpecificationC33/C33M, except that the requirements for gradation shall notapply.5.4 AdmixturesThe following admixtures and blends areallowable:5.4.1 Air-entraining admixture conforming to SpecificationC260/C
26、260M;5.4.2 Chemical admixture conforming to SpecificationC494/C494M;5.4.3 Chemical admixture for use in producing flowingconcrete conforming to Specification C1017/C1017M.5.4.4 Chemical admixture or blend approved by the owner.5.5 Steel ReinforcementReinforcement shall consist ofwelded wire reinforc
27、ement conforming to SpecificationA1064/A1064M or billet-steel bars conforming to Specifica-tion A615/A615M, Grade 60 or A706/A706M, Grade 60. Thebox culvert segments shall be manufactured with reinforce-ment meeting the yield strengths designated in the design of thebox culvert, but the yield streng
28、th shall not be less than 60 ksi.5.6 FibersSynthetic and non-synthetic fibers shall beallowed to be used, at the manufacturers option, in concreteboxes as a nonstructural manufacturing material. Syntheticfibers (Type II and Type III) and non-synthetic fiber (Type I)designed and manufactured specific
29、ally for use in concrete andconforming to the requirements of Specification C1116/C1116M shall be accepted.5.7 WaterWater used in the production of concrete shallbe potable or non-potable water that meets the requirements ofSpecification C1602/C1602M.6. Design6.1 Each segment of the box shall meet t
30、he requirements ofthe AASHTO LRFD Bridge Design Specifications. Guidanceis given in Appendix X1.6.2 The manufacturer shall maintain on file a copy of asealed “stamped” design by a professional engineer in accor-dance with the AASHTO LRFD Bridge Design Specificationsand this standard for each structu
31、re manufactured.6.3 The minimum compressive strength of concrete seg-ments produced to this standard shall be 4000 psi, unlessotherwise designated by the engineer.6.4 The manufacturer shall produce box culvert segmentsmeeting the design requirements designated in the design of thesegmental precast b
32、ox structure. As a minimum, the boxculvert segments shall meet the reinforcement layout, concretecover, and all other manufacturing details required by thisstandard.6.5 The manufacturer may request approval by the pur-chaser for modified designs which differ from the requirementsin this standard. Wh
33、en such modified designs are approved, itshall be so indicated on the manufactured box with thedesignation “C1786Modified.”NOTE 4(Advisory)Construction procedures, such as heavy equip-ment movement or stockpiling of material over or adjacent to a boxstructure can induce higher loads than those used
34、for the structures finaldesign. These construction and surcharge loads are allowable as long asthe final steel areas in the box are equal to or larger than those required forthe construction phase. The design engineer shall take into considerationthe potential for higher loads induced by constructio
35、n procedures indetermining the final design of the box structure.C1786 172FIG. 1 Segment Configuration OptionsC1786 1737. Reinforcement7.1 Placement of ReinforcementReinforcement shall beassembled utilizing any combination of single or multiplelayers of welded wire reinforcement, not to exceed three
36、 layers,or utilizing single or double layers of deformed billet steel bars.The cover of concrete over the circumferential reinforcementshall be 1 in. except for when the box culvert has less than 2 ftof earth cover, then the concrete cover over the top slabreinforcement shall be 2 inches (see Figs.
37、2 and 3). Concretecover shall be subject to the provisions of Section 11. Thewelded wire reinforcement shall be composed of circumferen-tial and longitudinal wires meeting the spacing requirements of7.2 and shall contain sufficient longitudinal wires extendingthrough the box section to maintain the
38、shape and position ofreinforcement. Longitudinal distribution reinforcement shall bewelded-wire reinforcement or deformed billet-steel bars andshall meet the spacing requirements of 7.2. The ends of thelongitudinal distribution reinforcement shall not be more than2 in. from the ends of the box secti
39、on. The exposure of the endsof longitudinals, stirrups, and spacers used to position thereinforcement shall not be a cause for rejection.7.2 Laps, Welds, and SpacingWhen deformed billet steelbars are utilized for the primary reinforcing, the requirementsin the AASHTO LRFD Bridge Design Specification
40、s, Section5.11 for splices and development of reinforcement shall befollowed. When wire reinforcement is utilized, the require-ments of this section shall be followed. Splices in the circum-ferential reinforcement shall be made by lapping. The overlapmeasured between the outermost longitudinal wires
41、 of eachreinforcement sheet shall not be less than the space containingtwo longitudinal wires of each mesh plus 2 in., but not less than10 inches. No splicing is permitted in individual slab segments.The outside circumferential reinforcement in the top or bottomslab of a three-sided segment shall be
42、 continuous with, orlapped with the outside circumferential reinforcement in thesides. If welds are made to welded wire circumferentialreinforcement, they shall be made only to selected circumfer-ential wires that are not less than 18 in. apart along thelongitudinal axis of the three-sided section.
43、When spacers arewelded to circumferential wires, they shall be welded only tothese selected circumferential wires. There shall be no weldingto other circumferential wires. No welds shall be made to theinside circumferential wires in the middle third of the top span.No welds shall be made to the outs
44、ide circumferential wires inthe top span within one fourth of the span from the corners orin any location in either leg. Welding of deformed billet steelbar circumferential reinforcement is prohibited in all cases.When distribution reinforcement is fastened to a cage bywelding, it shall be welded on
45、ly to longitudinal wires or barsand only near the ends of the three-sided section. The spacingcenter to center of the circumferential reinforcement shall notbe less than 2 in. nor more than 4 in. for welded wirereinforcement, or less than 2 in. nor more than 8 in. fordeformed billet steel bars. The
46、spacing center to center of thelongitudinal reinforcement shall not be more than 8 in. forwelded wire reinforcement or more than 12 in. for deformedbillet steel bars. If welds are made to Grade 60 reinforcing bars,weldable bars conforming to Specification A706/A706M shallbe used.NOTE 5(Advisory)The
47、AASHTO LRFD Bridge Design Specifica-tions should be consulted for weld requirements and development lengthsnot directly addressed in this standard.7.3 Minimum ReinforcementBox culvert sections withless than 2 ft of earth or pavement cover shall containdistribution reinforcement in the bottom of the
48、top slab inaccordance with Article 9.7.3.2 of the AASHTO LRFD BridgeDesign Specifications, but shall be no less than 0.002*Ag inaccordance with Article 12.11.4.3.FIG. 2 Top Slab Reinforcement Placement(Joint configuration is for illustration purposes only, and other configurations are acceptable.)C1
49、786 1748. Joints8.1 The ends of the box segments shall be of such designthat each segment can be fitted together to form a complete boxsection unit. The ends of the box section units shall be soformed that the sections can be laid together to make acontinuous line of box sections compatible with the permis-sible variations given in Section 11.8.2 Longitudinal joints shall be designed to carry the ap-plied vertical forces, and so formed so that they can beassembled to transmit forces and provide joint tightnessconsistent with the requirements for tran
