Concrete slab calculation gives error

Hi there,

I am posting this question upon request after e-mail contact. It has since been resolved for me.

I’m working on a concrete slab on pile-foundation, and I keep getting this error message.

The “Notification” list doesn’t give me any information to understand the problem. It only says “Suspected ill-conditioning or pivot is negative”.

This was eventually resolved for me. The plate thickness was too low, causing the upper and bottom layers of the calculation model to ‘collapse’, if I understand correctly.

I uploaded the file for educational purposes.
Tankpit A.xfem (390.8 KB)

Hi Arjen,

Thanks for your post.

You are fully right. If your plate thickness is too low, the concrete shell collapses and no reinforcement can be designed. The solution is to increase the plate thickness or to choose a higher concrete grade.

Kind regards
Rob Baaij