Non-Convergence of time history cases - Instability and ill conditioned structure
Non-Convergence of time history cases - Instability and ill conditioned structure
(OP)
Hi guys,
I am currently facing a problem with SAP 18.0.1 while running a model that is seismically isolated using triple friction pendulums.
9 non-linear time history cases are applied in the triplet directions (XYZ in same case).
Some of these cases are converging and some are not .. at the end of the non-linear analysis an instability and ill conditioned warning is shown as well.
I have checked the model many times, but I could not figure out what could be the reason of this non-convergence and the instability ..
Does anyone have an idea ?
Thanks,
I am currently facing a problem with SAP 18.0.1 while running a model that is seismically isolated using triple friction pendulums.
9 non-linear time history cases are applied in the triplet directions (XYZ in same case).
Some of these cases are converging and some are not .. at the end of the non-linear analysis an instability and ill conditioned warning is shown as well.
I have checked the model many times, but I could not figure out what could be the reason of this non-convergence and the instability ..
Does anyone have an idea ?
Thanks,





RE: Non-Convergence of time history cases - Instability and ill conditioned structure
RE: Non-Convergence of time history cases - Instability and ill conditioned structure
Maybe I have done something wrong, how could you see in the standard solvers such errors ?
RE: Non-Convergence of time history cases - Instability and ill conditioned structure
RE: Non-Convergence of time history cases - Instability and ill conditioned structure
What are the degree of tolerance? Did you check carefully lower order modes mybe there are some out of range/local failure which causing these errors. Investigate modal shapes by Ritz vectors, then crosscheck he connectivity of any used links. Plus, ensure adequate time-step, total duration, damping, and material properties.
Shoot for the Moon, even if U miss, U still land among Stars!
RE: Non-Convergence of time history cases - Instability and ill conditioned structure
Hi Shz713, thanks I will have a look at these issues.
RE: Non-Convergence of time history cases - Instability and ill conditioned structure
1) open de .s2k or .$2k file extension file. And then search the word "version" and change the version number with the one you will be opening it
3) Open a new instance of sap2000, blank model and go to file--> import ans select to impor the .s2k file
RE: Non-Convergence of time history cases - Instability and ill conditioned structure
I have tried to run the model in version 17.3.0, the instability issue have disappeared however the convergence issue for triplet time history cases with triple pendulum is still there ..