I am relatively new to ATENA, so forgive me if this is a fairly easy fix. I have looked through this forum and have not found anything that has fixed my issue though.

I am trying to model a 2d flexural test on a concrete beam composed of 3d printed concrete in the middle third of the beam surrounded by two traditionally cast segments on each end of the beam. I am having issues meshing the vertical interfaces between the concrete types (there are two interfaces). When I run my load tasks, I get an error that says "solver error: zero pivot, numerical factorization or iterative refinement problem, (possibly in equation: -3, node: 17, dof 2) in phase 23. Source line: 125."

What are the possible causes of this error?

Also, when trying to define my mesh in the preprocessor, sometimes when previewing the mesh, a warning occurs that says "T3D error while storing quad element 363 from group 100001 with property 0 located at interface id 1. Source line: 386." I assume this means one of the nodes or elements does not have material properties assigned, but I know I assigned both interfaces a material.

Thank you in advance to anyone who can help with these issues.