RISA Foundation Weak Axis Results Issue

[HristoM]

Hello,

I am concerned with some results I am getting from a Risa Foundation analysis. In particular, foundation member M6. The results are showing very large out of plane bending. From what I can gather, the result abnormality occurs at the edge of slab. I cannot gather why there is such a large out of plane loading. I do not understand what is happening or how to fix it. It almost looks like there are point loads located at edge of slab and acting in the same direction.

Could the soil region be causing this for any reason? It is in there to reduce the bearing capacity of the grade beams due to existing utilities below.

Attached is a screenshot of the beam results.

 

[JoshPlumSE]

It's impossible for me to tell why this is happening from just that picture. Obviously, those two slabs are moving laterally with respect to each other and this is causing the weak axis behavior in the grade beam.

I've seen cases where the torsional reaction at the base of a column will dramatically impact grade beams. This is often because the plate elements that make up the slab or mat foundations do not model in the "drilling" degree of freedom. It's possible that this is what you're seeing with this member.