1、Designation: C 857 07Standard Practice forMinimum Structural Design Loading for UndergroundPrecast Concrete Utility Structures1This standard is issued under the fixed designation C 857; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 o
3、r sectionalprecast concrete utility structures. Concrete pipe, box culverts,and material covered in Specification C 478 are excluded fromthis practice.NOTE 1For additional information see AASHTO Standard Specifica-tion for Highway Bridges, Seventeenth Edition.NOTE 2The purchaser is cautioned that he
4、 must properly correlate theanticipated loading conditions and the field requirements with the designloads used.1.2 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 This standard does not purport to address all of th
5、esafety 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. Referenced Documents2.1 ASTM Standards:2C 478 Specification for Pre
6、cast Reinforced Concrete Man-hole 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 canaffect the design of the structure.3.1.2 live loadswill consist
7、 of any moving loads that canaffect the design of the structure and their associated impactand surcharge loads.3.1.3 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 below ground
8、 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 desig-nations are given in Table 1. Live load wheel s
9、pacing is shownin Fig. 1.4.1.2 Impact:4.1.2.1 The live loads A-16, A-12, and A-8 should beincreased 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
10、) below 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 designc
11、alculations are as follows:Concrete, plain, and reinforced 150 lb/ft3(2043 kg/m3)Cast iron 450 lb/ft3(7208 kg/m3)Steel 490 lb/ft3(7850 kg/m3)Aluminum 175 lb/ft3(2804 kg/m3)Earth fill (dry) 110 lb/ft3(1762 kg/m3)Macadam 140 lb/ft3(2243 kg/m3)4.1.4 Distribution of Wheel Loads Through Earth Fills:4.1.4
12、.1 Wheel loads at ground level should be consideredapplied to a wheel load area as indicated in Fig. 2.4.1.4.2 Wheel loads should be distributed below groundlevel as a truncated pyramid, as shown in Fig. 3, in which thetop surface is the wheel load area and the distributed load areais equal to the f
13、ollowing:1This practice is under the jurisdiction of ASTM Committee C27 on PrecastConcrete Products and is the direct responsibility of Subcommittee C27.10 onUtility Structures.Current edition approved June 1, 2007. Published June 2007. Originallyapproved in 1978. Last previous edition approved in 2
14、001 as C 857 95 (2001).2For 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 o
15、f State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.DLA 5 W 1 1.75 H! L 1 1.75 H! (1)where:DLA = distributed load area, ft2(m2)
16、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 outside limits of the individual areas asindicated in Fig. 4. When the
17、dimensions of the com-positedistributed load area exceeds the roof area only that portion ofthe distributed load on the roof area shall be considered in thedesign.4.1.4.4 The distribution of wheel loads through earth fillmay be neglected when the depth of fill exceeds 8 ft (2.5 m).4.2 WallsThe desig
18、n loads for the walls of any structure ator below ground level will consist of surcharge loads resultingfrom live loads, dead loads that can develop as a result of earthpressure, hydrostatic pressure, and construc-tion materials suchas used for roadways and walkways. Load diagrams of liveload surcha
19、rge and dead loads are shown in Fig. 5.4.2.1 Live Loads:4.2.1.1 When traffic can come within a horizontal distancefrom the structure equal to one half the height of the structure,a live load surcharge pressure of not less than 0.5 % of thewheel loading of the traffic involved should be taken as the
20、liveload acting upon the wall of the structure.4.2.1.2 Surcharge pressures for various live loads trans-ferred to equivalent horizontal fluid pressure are as follows:A-16 16 000 lbf per wheel 3 0.005 = 80 lbf/ft2(3830 Pa) per wheelA-12 12 000 lbf per wheel 3 0.005 = 60 lbf/ft2(2873 Pa) per wheelA-8
21、8 000 lbf per wheel 3 0.005 = 40 lbf/ft2(1915 Pa) per wheelA-0.3 Refer to 4.2.2.14.2.1.3 Surcharge pressures resulting from live loads maybe neglected when the distance from ground level exceeds 8 ft(2.5 m).4.2.2 Dead Loads:4.2.2.1 The dead loads will consist of an earth pressureabove ground water l
22、evel and hydrostatic pressure plus amodified earth pressure below ground water level. The earthpressure above ground water level and the modified earthpressure below ground water level will be converted to ahorizontal pressure using Rankines Theory on active earthpressure. No structure will be desig
23、ned for less than a 30lb/ft2(1436 Pa) horizontal pressure.4.2.2.2 For the general case when structures are placed inareas where the soil surface does not slope the horizontalpressure acting at a point on the wall of the structure aboveground water level will be:P 5 Ka3 W 3 H (2)where:P = horizontal
24、pressure, lbf/ft2(Pa)Ka= coefficient of active earth pressure = (1 sin f)/(1+ sinf )f = angle of internal friction of the soil, deg (rad),W = unit weight of soil, lb/ft3(kg/m3) andH = distance from ground level to the point on the wallunder consideration, ft (m).4.2.2.3 In special cases, when struct
25、ures are placed in areaswhere the soil surface is sloping, the horizontal pressure actingat a point on the structure above ground water level is asfollows:P 5 cos d KaWsH (3)where:P = horizontal pressure, lbf/ft2(Pa),Ka= coefficient of active earth pressure =cos dcos d2=cos2d2cos2fcos d1=cos2d2cos2f
26、(4)f = angle of internal friction of the soil, deg (rad),d = angle between the sloping soil surface and the hori-zontal, deg (rad)Ws= unit weight of soil, lb/ft3(kg/m3), andH = distance from ground level to the point on the wallunder consideration, ft (m).The horizontal pressure below ground water l
27、evel resultingfrom the weight of soil above ground water level is equal to thehorizontal pressure at ground water level and will remainconstant from ground water level to the base of structure.4.2.2.4 The horizontal pressure that can develop belowground water level will consist of a full hydrostatic
28、 pressureplus horizontal pressure resulting from the weight of sub-merged soil. The hydrostatic pressure acting at a point on thewall of the structure below ground water level is:Pw5 WwHw(5)where:Pw= hydrostatic pressure, lbf/ft2(Pa),Ww= unit weight of water, lb/ft3(kg/m3), andHw= distance from grou
29、nd water level to the point onthe wall under consideration, ft (m).The horizontal pressure acting at a point on the wall of thestructure below ground water level resulting from the weight ofsubmerged soil is:Ps5 Ws2 Ww! KaHw(6)where:P = horizontal pressure from submerged soil, lbf/ft2(Pa)WsWw= unit
30、weight of soil less the unit weight of water,lb/ft3(kg/m3),Ka= coefficient of active earth pressure = (1 sinf)/(1 + sin f),f = angle of internal friction of the soil, deg (rad),andHw= distance from ground water level to the pointon the wall under consideration, ft (m).TABLE 1 Vehicle and Pedestrian
31、Load DesignationsDesignations Maximum Loads UsesA-16 (HS20-44)A16 000 lbf (71 172 N)/wheel heavy trafficA-12 (HS15-44)A12 000 lbf (53 376 N)/wheel medium trafficA-8 (H10-44)A8 000 lbf (35 586 N)/wheel light trafficA-0.3 300 lbf/ft2(14.4 kPa) walkwaysBAThe designations in parentheses are the correspo
32、ndingAASHTO designations.BAnticipated designs other than those listed should be designated by purchaser.C857072NOTE 3The coefficient of active earth pressure is used for the generalcase where the soil surface does not slope.4.3 Base:4.3.1 Live LoadsThe live loads transmitted to the baseconsist of th
33、e maximum value possible of live loads that can beimposed on the roof. This includes the total number of wheelloads that can simultaneously be placed on the structure.4.3.2 Dead LoadsThe dead loads on the base consist ofthe dead loads imposed on the roof plus the weight of thestructure excluding the
34、 base, or the hydrostatic pressure actingon the base, whichever is greater.4.4 Accessories Loading:4.4.1 Cable Pulling DevicesCable pulling devices in allstructures are designed for the working loads specified by thespecific user. These working loads can be compensated for inthe design of the struct
35、ure and are considered in addition to thedesign loads.4.4.2 Lifting DevicesLifting devices in all structures aredesigned for a load equivalent to three times the weight of thestructure, utilizing no more than three lifting points. The loadsimposed at the lifting points are considered in the design o
36、f thestructure.FIG. 1 Live Load SpacingC8570734.4.3 Equipment Mounting DevicesThe structure is de-signed to accommodate loads induced by the equipmentinstalled on the mounting device, as required by the user. Theseloads are considered in the design of the structure.5. Significance and Use5.1 This pr
37、actice is intended to standardize the minimumstructural design loading for underground precast concreteutility structures.5.2 The user shall verify the anticipated field conditions andrequirements with design loads greater than those specified inthis standard.6. Keywords6.1 minimum structural design
38、 criteria; precast concrete;underground utility enclosuresFIG. 2 Wheel Load AreaFIG. 3 Distributed Load AreaC857074FIG. 4 Overlapping Load AreasC857075FIG. 5 Load Diagrams of Live Load Surcharge and Dead LoadsC857076ASTM International takes no position respecting the validity of any patent rights as
39、serted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time
40、by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will rec
41、eive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Int
42、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C857077
