Unable to apply next load step

[vagelis]

Hello,

I'm using Seismostruct for a dynamic time history analysis of a 4-span bridge for my thesis. I apply the acceleration as a load with curve multiplier: 9.81(g value). When I run the analysis, after a while and after some damages(yield steel in sections of some columns), it stops the analysis and it says that : It is unable to apply the next load step.

At all performance criteria I have chosen "Keep Strength".

I'm using the Academic version of Seismostruct 2016.

Could you please give me a clue about my problem?

Thank you,
Vagelis

[huffte]

Did you post-processing the results and look at load - deflection plots? Is it possible that the structure has truly become unstable and reached its displacement capacity? Even if strength remains, stiffness may degrade to a condition of instability. If you send the model to me I will give it a look as I find time, but I would suggest some further analysis of results. Best of luck.