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Quasi Static Cyclic Push-Over Analysis

Posted: Wed Jan 22, 2020 2:57 am
by maitreyakurumbhati
Hello,

I am trying to use perform a simple load controlled Quasi Static Cyclic Push-Over Analysis of a simple portal frame.

The portal frame is supposed to be subjected to a nodal load vector.

Can anyone tell me how can I set up the analysis for the frame?

Also, if it set the "tsTag" in the loadpattern to "0" or "None" , will it be set by default to a "Plain" type time series?

Thank you,
Maitreya Manoj Kurumbhati

Re: Quasi Static Cyclic Push-Over Analysis

Posted: Wed Jan 22, 2020 9:51 am
by MassimoPetracca
If you want to do a cyclic push-over analysis with load-control and nodal loads, I assume that your model will never show a softening branch, otherwise you need to do a displacement-control or to apply an imposed displacement condition.

Assuming that you want to do a load-controlled cyclic analysis with nodal loads:
  1. create your model + define and assign physical properties and element properties
  2. define and assign conditions: 1) fixities, 2) verical loads, 3) horizontal loads
  3. define 2 time series, a linear one (for verical loads), and a Path one (for cyclic loading)
  4. in the analysis step: define
    • recorder
    • add constraint pattern
    • add load pattern -> vertical load with linear time series
    • analysis
    • add load pattern -> horizontal load with Path time series
    • analysis
Check out our e-learing web page, there are videos and materials from previous webinars, and a new webinar for next week, about micro-modeling of masonry structure. There we will show how to do a cyclic displacement-controlled analysis.

Re: Quasi Static Cyclic Push-Over Analysis

Posted: Mon Jan 27, 2020 4:41 pm
by maitreyakurumbhati
Thank you so much.

That perfectly answered my problem.

I just one more question, is there any way I can provide input of an adaptive analysis method like this? (other than sourcing the tcl file as a custom command in the analyses)

Herein I am asking the script to change the algorithm to say Newton if it hits convergence issues and then switch back to the original stated algorithm.
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Thanks again!!

Re: Quasi Static Cyclic Push-Over Analysis

Posted: Tue Jan 28, 2020 8:55 am
by STKO Team
In the current version you can't. However right now we are implementing adaptive time step directly in the analysis command, where the user can choose:
  1. fixed number of increments (the default for OpenSEES)
  2. adaptive time step based on convergence properties (i.e. changing the time step size)
  3. adaptive algorithm
I will let you know when this new feature will be available.