Topic: cyclic load model

Hi,
I'm a new ATENA user. I'm modelling a cyclic load on a RC column. I've already read the others posts on this topic but I've some problem with my model yet. I would like to know what type of solution parameters I've to use. I started with the Standart Arc Lenght, is it correct?how can I modify it to make my model suitable?
Thanks a lot.
Diego

Re: cyclic load model

The choice between Arc-Length and Newton-Raphson does not depend on cyclic or not cyclic, but whether you load by displacements or forces and if you need to get near- or postpeak results, see the section 3.8.5.1 Solution parameters in the ATENA 3D User's Manual.

Re: cyclic load model

Hi, thank you for the reply. I understand the difference now but I continue to have problems with the model. I briefly explain you: I’m trying to model a RC column with a stub in the middle where I apply the horizontal cyclic load as a prescribed deformation. So when the prescribed deformation begin to pull the stub the concrete fails in traction and the cycle ends. I can’t understand why, I’ve already control all the parameters of the materials. Please give me some indications.
Thank you.

Re: cyclic load model

Without seeing your model, it is impossible (or at least hard and not effective) to guess the reasons of the problems...
Please send us the model to our support email. Delete all results and the mesh, then ZIP (or RAR) the .cc3 file before attaching it to email.

Re: cyclic load model

Based on your short description, I think that your problem is cracking at the point of load application. When the load reverses to tension you see cracking there. This is quite natural and you have to make sure that this region is sufficiently reinforced. The reinforcement is probably also in your test setup, otherwise the cracking would be there as well.

Another solution is to never apply the load as tension, but in the reverse cycle apply the force or prescribed deformation from the otherside, so that you are applying always a compression and never tension.

Re: cyclic load model

Hi,
I’ve tried to model the cyclic load applying always compression as you say, but something very strange happens. I know it’s difficult to explain you the problem so I think it’s better to send you my model if it’s possible.
Thank you very much for the aid.

Re: cyclic load model

Yes, you can send us your data file to cervenka (at) cervenka dot cz. Regards Jan

Re: cyclic load model

Hi,
Thank you for the answers and the advices. I’ve managed to model the cyclic load but the column can’t reach the maximum load which results from the experimental trial and seems to be less ductile in displacement.
I can’t find a solution, have you some tips to give me?Maybe some parameters to change?
Thank you so much.
Diego

Re: cyclic load model

Please send us the ATENA model + the experimental and analysis results data plotted into one graph.

Things to check are
1. reinforcement material - you probably need to include hardening
2. basic concrete material parameters, above all E, fc, ft. Are you using the mean values from a static test?
Do not forget that if you have ft from another test than direct tension, you need to adjust the value (typically, decrease by 10-40%, depending on the test).
3. after we have your latest model, we may change some of the advanced parameters like the ultimate plastic displacement (Wd), tension stiffening, plastic strain at compressive strength (eps_cp), or other.