RAM Elements, Version 13.4 - Nonlinear Analysis with Temperature Load

Question

I am currently working on a concrete frame model using RAM Elements. I have been able to get the non-linear analysis to run on the model; however, when I add a temperature load, the non-linear analysis crashes. Can anyone provide me with any pointers on this?

Seth Guthrie · Answer

It's working OK for me with 13.04.01.208. Is your model non-linear due to the presence of tension-only members, compression-only springs or just from using P-Delta? Are the thermal loads applied to linear members, shells or both? Better yet, send over your current file for review.

Seth Guthrie · Answer

I got your file, but it does not seem to include the custom sections and materials from your file so I can't rerun it. What I can tell is that after meshing the model has about 500 nodes and 5000 shells. It has 35 load cases, but more importantly 293 load combinations. When you switch to P-Delta analysis it's necessary to analyze each load combinations (and load case) and iterate on each until deflections converge. So if it takes 3 iterations to get convergence in a P-Delta analysis and you run all load combinations it would take at least (293+35)/35)*2.5 = 23 times as long as first order analysis. It's also possible that it's running out of memory of course. 
 
To test it a little more rigorously I would first run dead load and thermal load only in first order analysis to see how long it takes. Then try running a combination of dead and thermal (only) in P-Delta analysis. 
 
If the analysis time is too long to make these tests practical try increasing the mesh size first. Also, make the P-Delta convergence tolerance something larger, e.g. 0.001. 
 
If it really does turn out to be a problem with thermal loads and P-Delta, and not simply a matter of time/memory, let me know and I'll dig in further.