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The program will not only investigate the maximum lateral earth pressure but will also investigate the minimum lateral earth pressure acting on the outside walls. This is an AASHTO loading condition to check for maximum positive moments in the top and bottom slabs. For STND and LRFD
For the Standard specification, the
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software uses an equivalent fluid pressure method to calculate the horizontal soil pressure
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.
For the LRFD specifications, users have the option of selecting how the horizontal soil pressure is calculated,
Equivalent fluid pressure
Active earth pressure
At-rest earth pressure
For the AREMA specifications, the software uses the soil weight multiplied by the minimum and maximum lateral pressure coefficients.
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For the CHBDC specifications, the program uses the unit weight of the soil in conjunction with the Horizontal Arching Factors from Table 7.11, again depending on the installation type.
Internal Water Pressure
Water pressure inside the culvert barrel can reverse the wall moments and add to slab positive moments and may be checked. The program is able to use full height or partial depth of water pressure and no water pressure as two loading cases. Internal water pressure Water weight is taken as 62.4 pcf.
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Load Load Combinations
Load combinations are created based on code requirements. Generally, they are broadly grouped into service and strength categories.
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Strength combinations are checked for shear and flexural strength.
For STND and AREMA, we only have one load combination to check:
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In the above equation, DL includes concrete, soil and water dead loads.
For LRFD, we check three Eriksson Culvert checks four load combinations:
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Maximum vertical
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force on the roof, and maximum
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inward force on the walls
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DCmax + DWmax + EVmax + EHmin + (LL+IM)max + WAmax
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:
Minimum vertical force on the roof, and maximum inward
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force on the walls
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DCmin + DWmin + EVmin + EHmax + LSmax
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:
Minimum vertical force on the roof, and maximum
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outward force on the walls:
Maximum vertical force on the roof,
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DCmax + DWmax + EVmax + EHmax + LSmax + (LL+IM)max
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and minimum outward force on the walls:
For CHBDC, we check five load combinations are checked: For maximum
Maximum vertical load on the roof and minimum horizontal inward on the walls
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DCmax + DWmax + EVmax + (LL+IM)max + EHmin + WAmax
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:
Maximum vertical on the roof and maximum horizontal inward on the walls
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DCmax + DWmax + EVmax + (LL+IM)max + EHmax + WAmin
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:
Minimum vertical on the roof and maximum horizontal inward on the walls
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DCmin + DWmin + EVmin + EHmax + WAmin
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:
Maximum vertical on the roof and maximum horizontal inward on the walls
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DCmax + DWmax + EVmax + LSmax + EHmax + WAmin
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:
Minimum vertical on the roof and maximum horizontal inward on the walls
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:
