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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 or partial depth of water pressure and no water pressure as two loading cases. Water weight is taken as 62.4 pcf. The input is the height of the water table above the centerline of the top slab for exterior water pressure, and the elevation head above the bottom of the top slab for the interior water pressure. So, for example, an interior pressure head input of 0-ft indicates a triangular pressure load resulting from the culvert being filled with water, but no additional pressure.
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Load Combinations
Load combinations are created based on code requirements. Generally, they are broadly grouped into service and strength categories.
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For LRFD, Eriksson Culvert checks four load combinations:
Maximum vertical force on the roof, and maximum inward force on the walls:
Minimum vertical force on the roof, and maximum inward force on the walls:
Minimum vertical force on the roof, and maximum outward force on the walls:
Maximum vertical force on the roof, and minimum outward force on the walls:
For CHBDC, five load combinations are checked:
Maximum vertical load on the roof and minimum horizontal inward on the walls:
Maximum vertical on the roof and maximum horizontal inward on the walls:
Minimum vertical on the roof and maximum horizontal inward on the walls:
Maximum vertical on the roof and maximum horizontal inward on the walls:
Minimum vertical on the roof and maximum horizontal inward on the walls:
