When Caesar informs the user that the "Stiffness Matrix has been detected as being almost numerically singular", what does it mean?
(residuals cannot converge?)

My model contains:
- 2 anchors (one at each end)
- no CNodes
- no structural stuff

I am reluctant to change the "Decomposition_Singularity_Tolerance" yet. Is there a quick way to locate any "rigid body motion"?

Thanks

There is no "quick way" to locate what is causing the rigid body motion.

Do you by chance have expansion joints in the model? If so, are all the necessary stiffnesses defined and realistic? Also, be careful putting expansion joints in series without intermediate restraints, as this will define a linkage - which allows rigid body motion.

If this isn't the problem, send us your job and we'll take a look at it.

The model does not have expansion joints.
I've just sent you the model file.

Thanks