1、Designation:C85707 Designation: C857 11Standard 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 th
2、e 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 practice describes the minimum live loads and dead loads to be applied when desig
3、ning monolithic or sectional precastconcrete utility structures. Concrete pipe, box culverts, and material covered in Specification C478 are excluded from this practice.NOTE 1For additional information see AASHTO Standard Specification for Highway Bridges, Seventeenth Edition.NOTE 2The purchaser is
4、cautioned that he must properly correlate the anticipated loading conditions and the field requirements with the design loadsused.1.2The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for informationonly.1.2 The values stated in inch-pound u
5、nits are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the res
6、ponsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C478 Specification for Precast Reinforced Concrete Manhole Sections2.2 AASHTO Standard:Specifi
7、cation 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 can affect the design of the structure.3.1.2 live loadswill consist of any moving loads that can affect the design of the structure and
8、 their associated impact andsurcharge 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 at or below ground level consists of the live loads including impactand dead loads
9、that can develop as a result of earth pressure, hydrostatic pressure, and construction materials such as used forroadways and walkways.4.1.1 Live LoadsThe vehicle and pedestrian load designations are given in Table 1. Live load wheel spacing is shown in Fig.1.4.1.2 Impact:4.1.2.1 The live loads A-16
10、, A-12, and A-8 should be increased as follows to sustain the effect of impact:4.1.2.2 Live Load Increase:1This practice is under the jurisdiction of ASTM Committee C27 on Precast Concrete Products and is the direct responsibility of Subcommittee C27.10 on UtilityStructures.Current edition approved
11、June 1, 2007. Published June 2007. Originally approved in 1978. Last previous edition approved in 2001 as C85795 (2001). DOI:10.1520/C0857-07.Current edition approved March 1, 2011. Published March 2011. Originally approved in 1978. Last previous edition approved in 2007 as C857 07. DOI:10.1520/C085
12、7-11.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from American Association of State Highway and
13、 Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possi
14、ble to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
15、t Conshohocken, PA 19428-2959, United States.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 ground level, 10 %TABLE 1 Vehicle and Pedestrian Load DesignationsDesignations Maximum Loads UsesA-16 (HS20-44)A16 00
16、0 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 correspondingAASHTO designations.BAnticipated designs other than those liste
17、d should be designated by purchaser.FIG. 1 Live Load SpacingC857 11236 in. (914 mm) or more below ground level, 0 %4.1.3 Dead LoadsDead loads will consist of the weight of the roof, roadbed, walkways, earth fill, access opening covers, andany other material that produces a static load.4.1.3.1 Recomm
18、ended unit weights of materials for design calculations 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 Distribut
19、ion of Wheel Loads Through Earth Fills:4.1.4.1 Wheel loads at ground level should be considered applied to a wheel load area as indicated in Fig. 2.4.1.4.2 Wheel loads should be distributed below ground level as a truncated pyramid, as shown in Fig. 3, in which the topsurface is the wheel load area
20、and the distributed load area is equal to the following:DLA 5 W 1 1.75 H! L 1 1.75 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, the total load shall be con
21、sidered as uniformly distributed over the areadefined by the outside limits of the individual areas as indicated in Fig. 4. When the dimensions of the com-posite distributed loadarea exceeds the roof area only that portion of the distributed load on the roof area shall be considered in the design.4.
22、1.4.4 The distribution of wheel loads through earth fill may be neglected when the depth of fill exceeds 8 ft (2.5 m).4.2 WallsThe design loads for the walls of any structure at or below ground level will consist of surcharge loads resulting fromlive loads, dead loads that can develop as a result of
23、 earth pressure, hydrostatic pressure, and construc-tion materials such as usedfor roadways and walkways. Load diagrams of live load surcharge and dead loads are shown in Fig. 5.4.2.1 Live Loads:4.2.1.1 When traffic can come within a horizontal distance from the structure equal to one half the heigh
24、t of the structure, a liveload surcharge pressure of not less than 0.5 % of the wheel loading of the traffic involved should be taken as the live load actingupon the wall of the structure.4.2.1.2 Surcharge pressures for various live loads transferred to equivalent horizontal fluid pressure are as fo
25、llows: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 8 000 lbf per wheel 3 0.005 = 40 lbf/ft2(1915 Pa) per wheelA-0.3 Refer to 4.2.2.1FIG. 2 Wheel Load AreaC857 1134.2.1.3 Surcharge pressures resulting from live l
26、oads may be neglected when the distance from ground level exceeds 8 ft (2.5m).4.2.2 Dead Loads:4.2.2.1 The dead loads will consist of an earth pressure above ground water level and hydrostatic pressure plus a modified earthpressure below ground water level. The earth pressure above ground water leve
27、l and the modified earth pressure below groundwater level will be converted to a horizontal pressure using Rankines Theory on active earth pressure. No structure will bedesigned for less than a 30 lb/ft2(1436 Pa) horizontal pressure.4.2.2.2 For the general case when structures are placed in areas wh
28、ere the soil surface does not slope the horizontal pressureacting at a point on the wall of the structure above ground water level will be:P 5 Ka3 W 3 H (2)where:P = horizontal pressure, lbf/ft2(Pa)Ka= coefficient of active earth pressure = (1 sin f)/(1 + sinf )f = angle of internal friction of the
29、soil, deg (rad),W = unit weight of soil, lb/ft3(kg/m3) andH = distance from ground level to the point on the wall under consideration, ft (m).4.2.2.3 In special cases, when structures are placed in areas where the soil surface is sloping, the horizontal pressure acting ata point on the structure abo
30、ve ground water level is as follows:P 5 cos d KaWsH (3)FIG. 3 Distributed Load AreaFIG. 4 Overlapping Load AreasC857 114where:P = horizontal pressure, lbf/ft2(Pa),Ka= coefficient of active earth pressure =cos dcos d2=cos2d2cos2fcos d1=cos2d2cos2f(4)f = angle of internal friction of the soil, deg (ra
31、d),d = angle between the sloping soil surface and the horizontal, deg (rad)Ws= unit weight of soil, lb/ft3(kg/m3), andH = distance from ground level to the point on the wall under consideration, ft (m).The horizontal pressure below ground water level resulting from the weight of soil above ground wa
32、ter level is equal to thehorizontal pressure at ground water level and will remain constant from ground water level to the base of structure.FIG. 5 Load Diagrams of Live Load Surcharge and Dead LoadsC857 1154.2.2.4 The horizontal pressure that can develop below ground water level will consist of a f
33、ull hydrostatic pressure plushorizontal pressure resulting from the weight of submerged soil. The hydrostatic pressure acting at a point on the wall of thestructure 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= dist
34、ance from ground water level to the point on the wall under consideration, ft (m).The horizontal pressure acting at a point on the wall of the structure below ground water level resulting from the weight ofsubmerged soil is:Ps5 Ws2 Ww! KaHw(6)where:P = horizontal pressure from submerged soil, lbf/ft
35、2(Pa)WsWw= unit weight of soil less the unit weight of water, lb/ft3(kg/m3),Ka= coefficient of active earth pressure = (1 sin f)/(1 + sin f),f = angle of internal friction of the soil, deg (rad), andHw= distance from ground water level to the point on the wall under consideration, ft (m).NOTE 3The c
36、oefficient of active earth pressure is used for the general case where the soil surface does not slope.4.3 Base:4.3.1 Live LoadsThe live loads transmitted to the base consist of the maximum value possible of live loads that can beimposed on the roof. This includes the total number of wheel loads tha
37、t can simultaneously be placed on the structure.4.3.2 Dead LoadsThe dead loads on the base consist of the dead loads imposed on the roof plus the weight of the structureexcluding the base, or the hydrostatic pressure acting on the base, whichever is greater.4.4 Accessories Loading:4.4.1 Cable Pullin
38、g DevicesCable pulling devices in all structures are designed for the working loads specified by the specificuser. These working loads can be compensated for in the design of the structure and are considered in addition to the design loads.4.4.2 Lifting DevicesInsertsLifting devicesinserts in all st
39、ructures are designed for a load equivalent to threefour times theweight of the structure, utilizing no more than three lifting points. The loads imposed at the lifting points are considered in thedesign of the structure.4.4.3 Equipment Mounting DevicesThe structure is designed to accommodate loads
40、induced by the equipment installed onthe mounting device, as required by the user. These loads are considered in the design of the structure.5. Significance and Use5.1 This practice is intended to standardize the minimum structural design loading for underground precast concrete utilitystructures.5.
41、2 The user shall verify the anticipated field conditions and requirements with design loads greater than those specified in thisstandard.6. Keywords6.1 minimum structural design criteria; precast concrete; underground utility enclosuresC857 116ASTM International takes no position respecting the vali
42、dity of any patent rights asserted 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 subj
43、ect to revision at any time 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 Headquar
44、ters. Your comments will receive 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 standar
45、d is copyrighted by ASTM International, 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C857 117
