ASTM C857-19

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Designation: C857 − 16 C857 − 19
Standard Practice for
Minimum Structural Design Loading for Underground
Precast Concrete Utility Structures
This standard is issued under the fixed designation C857; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice describes the minimum live loads and dead loads to be applied when designing monolithic or sectional precast
concrete utility structures. Concrete pipe, box culverts, and material covered in Specification C478 are excluded from this practice.
NOTE 1—For additional information see AASHTO Standard Specification for Highway Bridges, Seventeenth Edition.
NOTE 2—The purchaser is cautioned that he must properly correlate the anticipated loading conditions and the field requirements with the design loads
used.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions 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 responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C478 Specification for Circular Precast Reinforced Concrete Manhole Sections
2.2 AASHTO Standard:
Specification for Highway Bridges, Seventeenth Edition
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 dead loads—will consist of any other load that can affect the design of the structure.
3.1.2 lateral earth loads—the lateral pressure due to the effective weight of adjacent earth backfill.
3.1.3 lifting insert—device embedded or otherwise attached to the structure, designed and manufactured to support a measured,
sustained, concentrated load.
3.1.4 live loads—will consist of any moving loads that can affect the design of the structure and their associated impact and
surcharge loads.
3.1.5 utility structure—a structure that is used by electric, gas, communication, or similar industries.
4. Design Loads
4.1 Roof—The design loads for the roof of any structure at or below ground level consists of the live loads including impact
and dead loads that can develop as a result of earth pressure, hydrostatic pressure, and construction materials such as used for
roadways and walkways.
This practice is under the jurisdiction of ASTM Committee C27 on Precast Concrete Products and is the direct responsibility of Subcommittee C27.10 on Utility
Structures.
Current edition approved Sept. 1, 2016July 1, 2019. Published September 2016July 2019. Originally approved in 1978. Last previous edition approved in 20142016 as
C857 – 14.C857 – 16. DOI: 10.1520/C0857-16.10.1520/C0857-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American Association of State Highway and Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
http://www.transportation.org.
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C857 − 19
4.1.1 Live Loads—The 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, A-12, and A-8 shall be increased 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 ground level, 10 %
36 in. (914 mm) or more below ground level, 0 %
4.1.3 Dead Loads—Dead loads will consist of the weight of the 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 design calculations are as follows:
3 3
Concrete, plain, and reinforced 150 lb/ft (2043 kg/m )
3 3
Cast iron 450 lb/ft (7208 kg/m )
3 3
Steel 490 lb/ft (7850 kg/m )
3 3
Aluminum 175 lb/ft (2804 kg/m )
3 3
Earth fill (dry) 110 lb/ft (1762 kg/m )
3 3
Macadam 140 lb/ft (2243 kg/m )
4.1.4 Distribution of Wheel Loads Through Earth Fills:
4.1.4.1 Wheel loads at ground level shall be considered applied to a wheel load area as indicated in Fig. 2.
4.1.4.2 Wheel loads shall be distributed below ground level as a truncated pyramid, as shown in Fig. 3, in which the top surface
is the wheel load area and the distributed load area is equal to the following:
DLA 5 W11.75 H L11.75 H (1)
~ ! ~ !
where:
2 2
DLA = distributed load area, ft (m )
W = wheel load width, ft (m),
L = wheel load length, ft (m), and
H = depth of fill, ft (m).
4.1.4.3 When several distributed load areas overlap, the total load shall be considered as uniformly distributed over the area
defined by the outside limits of the individual areas as indicated in Fig. 4. When the dimensions of the com-posite distributed load
area exceeds the roof area only that portion of the distributed load on the roof area shall be considered in the design.
4.1.4.4 The distribution of wheel loads through earth fill are neglected when the depth of fill exceeds 8 ft (2.5 m).
4.2 Walls—The design loads for the walls of any structure at or below ground level will consist of surcharge loads resulting from
live loads, lateral earth loads that can develop as a result of earth pressure, hydrostatic pressure, and construction materials such
as used for roadways and walkways. Load diagrams of live load surcharge and lateral earth 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 height of the structure, a live
load surcharge pressure of not less than 0.5 % of the wheel loading of the traffic involved shall be taken as the live load acting
upon the wall of the structure.
4.2.1.2 Surcharge pressures for various live loads transferred to equivalent horizontal fluid pressure are as follows:
A-16 16 000 lbf wheel load × 0.005 = 80 lbf/ft (3830 Pa)
A-12 12 000 lbf wheel load × 0.005 = 60 lbf/ft (2873 Pa)
A-8 8 000 lbf wheel load × 0.005 = 40 lbf/ft (1915 Pa)
A-8 8000 lbf wheel load × 0.005 = 40 lbf/ft (1915 Pa)
A-0.3 Refer to 4.2.2.1
4.2.1.3 Surcharge pressures resulting from live loads are neglected when the distance from ground level exceeds 8 ft (2.5 m)
...