ASTM C857-95(2001)
(Practice)Standard Practice for Minimum Structural Design Loading for Underground Precast Concrete Utility Structures
Standard Practice for Minimum Structural Design Loading for Underground Precast Concrete Utility Structures
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 C 478 are excluded from this practice.
Note 1—For additional information see AASHTO Standard Specification for Highway Bridges, Fifteenth 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 the standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:C857–95 (Reapproved 2001)
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 live loads—will consist of any moving loads that can
affect the design of the structure and their associated impact
1.1 Thispracticedescribestheminimumliveloadsanddead
and surcharge loads.
loads to be applied when designing monolithic or sectional
3.1.3 utility structure—a structure that is used by electric,
precast concrete utility structures. Concrete pipe, box culverts,
gas, communication, or similar industries.
and material covered in Specification C478 are excluded from
this practice.
4. Design Loads
NOTE 1—For additional information seeAASHTO Standard Specifica-
4.1 Roof—The design loads for the roof of any structure at
tion for Highway Bridges, Fifteenth Edition.
or below ground level consists of the live loads including
NOTE 2—Thepurchaseriscautionedthathemustproperlycorrelatethe
impact and dead loads that can develop as a result of earth
anticipated loading conditions and the field requirements with the design
pressure, hydrostatic pressure, and construction materials such
loads used.
as used for roadways and walkways.
1.2 The values stated in inch-pound units are to be regarded
4.1.1 Live Loads—The vehicle and pedestrian load desig-
as the standard. The values given in parentheses are for
nations are given inTable 1. Live load wheel spacing is shown
information only.
in Fig. 1.
1.3 This standard does not purport to address all of the
4.1.2 Impact:
safety concerns, if any, associated with its use. It is the
4.1.2.1 The live loads A-16, A-12, and A-8 should be
responsibility of the user of this standard to establish appro-
increased as follows to sustain the effect of impact:
priate safety and health practices and determine the applica-
4.1.2.2 Live Load Increase:
bility of regulatory limitations prior to use.
0 to 12 in. (0 to 305 mm) below ground level, 30%
2. Referenced Documents
13 to 24 in. (330 to 610 mm) below ground level, 20%
2.1 ASTM Standards:
25 to 35 in. (635 to 889 mm) below ground level, 10%
C478 Specification for Precast Reinforced Concrete Man-
36 in. (914 mm) or more below ground level, 0%
hole Sections
4.1.3 DeadLoads—Deadloadswillconsistoftheweightof
2.2 AASHTO Standard:
the roof, roadbed, walkways, earth fill, access opening covers,
Specification for Highway Bridges, Fifteenth Edition
and any other material that produces a static load.
4.1.3.1 Recommended unit weights of materials for design
3. Terminology
calculations are as follows:
3.1 Definitions of Terms Specific to This Standard:
3 3
Concrete, plain, and reinforced 150 lb/ft (2043 kg/m )
3.1.1 dead loads—will consist of any other load that can
3 3
Cast iron 450 lb/ft (7208 kg/m )
3 3
affect the design of the structure.
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 )
This practice is under the jurisdiction of ASTM Committee C27 on Precast
Concrete Products and is the direct responsibility of Subcommittee C27.10on
4.1.4 Distribution of Wheel Loads Through Earth Fills:
Utility Structures.
4.1.4.1 Wheel loads at ground level should be considered
Current edition approved Nov. 10, 1995. Published February 1996. Originally
applied to a wheel load area as indicated in Fig. 2.
published as C857–78. Last previous edition C857–87(1994).
Annual Book of ASTM Standards, Vol 04.05.
Available from American Association of State Highway and Transportation
Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C857
TABLE 1 Vehicle and Pedestrian Load Designations
horizontal pressure using Rankine’s Theory on active earth
Designations Maximum Loads Uses pressure. No structure will be designed for less than a 30
A
lb/ft (1436 Pa) horizontal pressure.
A-16 (HS20-44) 16 000 lbf (71 172 N)/wheel heavy traffic
A
A-12 (HS15-44) 12 000 lbf (53 376 N)/wheel medium traffic
4.2.2.2 For the general case when structures are placed in
A
A-8 (H10-44) 8 000 lbf (35 586 N)/wheel light traffic
areas where the soil surface does not slope the horizontal
2 B
A-0.3 300 lbf/ft (14.4 kPa) walkways
pressure acting at a point on the wall of the structure above
A
ThedesignationsinparenthesesarethecorrespondingAASHTOdesignations.
B
ground water level will be:
Anticipateddesignsotherthanthoselistedshouldbedesignatedbypurchaser.
P 5K 3W 3H (2)
a
4.1.4.2 Wheel loads should be distributed below ground
where:
level as a truncated pyramid, as shown in Fig. 3, in which the
P = horizontal pressure, lbf/ft (Pa)
top surface is the wheel load area and the distributed load area
K = coefficient of active earth pressure = (1 − sin f)/(1
a
is equal to the following:
+ sinf )
DLA 5 ~W 11.75H! ~L 11.75H! (1)
f = angle of internal friction of the soil, deg (rad),
3 3
W = unit weight of soil, lb/ft (kg/m ) and
where:
H = distance from ground level to the point on the wall
2 2
DLA = distributed load area, ft (m )
under consideration, ft (m).
W = wheel load width, ft (m),
4.2.2.3 In special cases, when structures are placed in areas
L = wheel load length, ft (m), and
wherethesoilsurfaceissloping,thehorizontalpressureacting
H = depth of fill, ft (m).
at a point on the structure above ground water level is as
4.1.4.3 When several distributed load areas overlap, the
follows:
total load shall be considered as uniformly distributed over the
area defined by the outside limits of the individual areas as P 5cos dK W H (3)
a s
indicated in Fig. 4. When the dimensions of the com-posite
where:
distributed load area exceeds the roof area only that portion of
P = horizontal pressure, lbf/ft (Pa),
the distributed load on the roof area shall be considered in the
K = coefficient of active earth pressure =
a
design.
2 2
4.1.4.4 The distribution of wheel loads through earth fill cosd2 cos d2cos f
=
cos
...
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