Hello Stressers!!!

Which of the two method above is more accurate in terms of dynamic results? Are there beam element software that you know that uses direct integration time history analysis?

Many Thanks in advance,

The difference is as "I want to see what's happening with my system when subject to a specific dynamic event" and "I accept to evaluate less accurate but conservative my system to avoid troubles under dynamic events".
See for example seismic codes based on earthquake spectra.
I mean they have different reasons to be performed.

Thanks Mariog. That's correct. For ill-defined loads it's hard to do a direct integration time history since earthquake spectra varies. But let's say if I have a well-defined event, or it's just too computationally expensive to program a direct integration time history method?

Many Thanks,

Cheers!!!

I'm not sure I understand your point.
Time History is available in Caesar, it requires you to be more precise with the input data and for the user it may be of interest that would take longer to run.
What means direct integration, do you refer to the possibility to see how the calculation is made?

I have watched the webinar presented by Mr. Dave on the topic "Dynamic Analysis IV (Time History Analysis)". On this webinar, it was mentioned that Caesar II uses Modal Time History Analysis not direct Integration Time History. I have checked other software and basically uses Modal time history also. Just curious, if there are other software which uses direct integration. Anyway, I'm satisfied now with the CII results, I have compared it with Ansys Workbench Transient Structural analysis and produce same results. Maybe this direct integration is similar to explicit dynamics in Ansys.

Cheers!!!

Now, I understand what you are referring to.
I don't know how Caesar is handling the calculation, but I can quote from CSI site (SAP2000, Etabs) and I suppose here it is a similar approach:
"Nonlinear modal time-history analysis, also known as Fast Nonlinear Analysis (FNA), is generally more accurate and efficient than direct-integration time-history analysis. The accuracy of FNA depends upon the sufficiency of suitable mode shapes, similar to how direct integration requires small enough time steps to accurately characterize dynamic behavior."

That's right Mariog. So in this case, modal time history analysis is accurate as long as we capture enough mode shapes that will contribute to the total response of the system.

Cheers!!