1、Designation:C85716Standard Practice forMinimum Structural Design Loading for UndergroundPrecast Concrete Utility Structures1This standard is issued under the fixed designation C857;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the
2、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 practice describes the minimum live loads and deadloads to be applied when designing monolithic or sectionalpr
3、ecast concrete utility structures.Concrete pipe,box culverts,and material covered in Specification C478 are excluded fromthis practice.NOTE1For additional information see AASHTO Standard Specifica-tion for Highway Bridges,Seventeenth Edition.NOTE2The purchaser is cautioned that he must properly corr
4、elate theanticipated loading conditions and the field requirements with the designloads used.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered st
5、andard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Reference
6、d Documents2.1 ASTM Standards:2C478 Specification for Circular Precast Reinforced ConcreteManhole Sections2.2 AASHTO Standard:Specification for Highway Bridges,Seventeenth Edition33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 dead loadswill consist of any other load that cana
7、ffect the design of the structure.3.1.2 lateral earth loadsthe lateral pressure due to theeffective weight of adjacent earth backfill.3.1.3 lifting insertdevice embedded or otherwise attachedto the structure,designed and manufactured to support ameasured,sustained,concentrated load.3.1.4 live loadsw
8、ill consist of any moving loads that canaffect the design of the structure and their associated impactand surcharge loads.3.1.5 utility structurea structure that is used by electric,gas,communication,or similar industries.4.Design Loads4.1 RoofThe design loads for the roof of any structure ator belo
9、w ground level consists of the live loads includingimpact and dead loads that can develop as a result of earthpressure,hydrostatic pressure,and construction materials suchas used for roadways and walkways.4.1.1 Live LoadsThe vehicle and pedestrian load designa-tions are given in Table 1.Live load wh
10、eel spacing is shown inFig.1.4.1.2 Impact:4.1.2.1 The live loads A-16,A-12,and A-8 shall be in-creased as follows to sustain the effect of impact:4.1.2.2 Live Load Increase:0 to 12 in.(0 to 305 mm)below ground level,30%13 to 24 in.(330 to 610 mm)below ground level,20%25 to 35 in.(635 to 889 mm)below
11、 ground level,10%36 in.(914 mm)or more below ground level,0%4.1.3 Dead LoadsDead loads will consist of the weight ofthe roof,roadbed,walkways,earth fill,access opening covers,and any other material that produces a static load.4.1.3.1 Recommended unit weights of materials for designcalculations are a
12、s follows:Concrete,plain,and reinforced150 lb/ft3(2043 kg/m3)Cast iron450 lb/ft3(7208 kg/m3)Steel490 lb/ft3(7850 kg/m3)Aluminum175 lb/ft3(2804 kg/m3)Earth fill(dry)110 lb/ft3(1762 kg/m3)Macadam140 lb/ft3(2243 kg/m3)4.1.4 Distribution of Wheel Loads Through Earth Fills:1This practice is under the jur
13、isdiction of ASTM Committee C27 on PrecastConcrete Products and is the direct responsibility of Subcommittee C27.10 onUtility Structures.Current edition approved Sept.1,2016.Published September 2016.Originallyapproved in 1978.Last previous edition approved in 2014 as C857 14.DOI:10.1520/C0857-16.2Fo
14、r referenced ASTM standards,visit the 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 Transportat
15、ionOfficials(AASHTO),444 N.Capitol St.,NW,Suite 249,Washington,DC 20001,http:/www.transportation.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.1.4.1 Wheel loads at ground level shall be consideredapplied to a wheel load area as in
16、dicated in Fig.2.4.1.4.2 Wheel loads shall be distributed below ground levelas a truncated pyramid,as shown in Fig.3,in which the topsurface is the wheel load area and the distributed load area isequal to the following:DLA5W11.75 H!L11.75 H!(1)where:DLA=distributed load area,ft2(m2)W=wheel load width,ft(m),L=wheel load length,ft(m),andH=depth of fill,ft(m).4.1.4.3 When several distributed load areas overlap,thetotal load shall be considered as uniformly distributed over thearea defined by the ou
