In the output file, I see the following Note. **NOTE- Tension/Compression converged after 5 iterations, Case= 3 . What does it mean?
If the model contains any of the following data, it could trigger that Note.
a) MEMBER TENSION b) MEMBER COMPRESSION c) SPRING TENSION d) SPRING COMPRESSION e) PLATE MAT with the COMPRESSION optionf) ELASTIC MAT with the COMPRESSION option
In all these cases, the program has to use an iterative method to find out which member or support spring should be switched off and which ones need to be treated as active. For example if a member designated as a compression member or a spring designated as a compression spring, is found to develop tension force after an analysis iteration, these would have to be switched off and the analysis re-run with the remaining members or springs. If the components of the structure that are active at the start of an iteration are the same as those at the conclusion of the iteration, convergence is said to have been attained.
The message is reported as a Note because it enables us to understand how many iterations it took to attain convergence for a load case. It is not indicative of anything wrong.While stabilizing load cases like gravity alone can be solved usually in just one iteration, when they are combined with destabilizing load cases like seismic or wind, more than one iteration may be needed.