Basement walls & underground tanks

[cozanostra]

Hi,

it seems that not many have attempted to apporach this issue but when designing a concrete basement wall or an underground concrete tank, the simplest approach i know is to use the PCA-published moment and shear coefficients or FEM it. Now the question is it all depends on on the fixity we assume. So far I examine both fixed and pinned conditions and pick the worst case , but i have a feeling that im making the design too conservative. Any thoughts on this?

Eg. lets say i have a 20ft long basement wall supported on piles below and at the ends by prependicular walls, as well as a conc floor at the bottom. There are quite a few fixity combinations we can make between all 3 sides. Is there a "prevailing" boundary condition for each side that we can pick beeing closer to reality?

 

[kslee1000]

The "reality" in basement wall & underground tank is "high uncertainty". To reach that, we will need real (?) soil properties, true/steady (?) water table, not to mention dynamic loadings & responses.

However, assume all been tought in college were good enough (static, linear...), the best approach to get around guessing the boundary condition is to make a close to real 3D model, and analyzed by computer program. This is a personal view, others might have better approach.