H20 loads at shallow burial.

[obrockmeier]

Hello.

I am using FEA to evaluate a thermoplastic chamber buried 18 inches below the surface (no pavement) to withstand an H20 load. The loads predicted by LRFD bridge design std seem very high and result in cost-preventative designs. Any comments on how to model (loads and constraints)thermoplastic chambers for shallow burial (less than 2ft) would be much appreciated.

 

[miecz]

I think your stuck with AASHTO wheel loads, including impact, unless you can bollard around your structure to prevent trucks from crossing. For these cases, I make a 3D finite element model, and include any openings in the top slab. If you have no openings, I suppose you can do a two-way slab design, but wastewater treatment chambers I work with usually have an access hatch. The wheel load can be distributed to a 10"x20" element, but that doesn't help much.

 

[dicksewerrat]

2 feet is usually too shallow for platic pipes. But you could change materials.