Seismosoft | Earthquake Engineering Solutions

I’m doing static pushover analysis to evaluate the ductility factor of RC frames with CONFINED-FRP sections. During my analysis, everytime that I applied con_frp material, and assigned this material behavior to a beam or column section, an error prompting me “Unable to apply the entire phase load. Phase terminated” appeared.

I should also mention that the same RC 2D frame without con_frp material behavior converged in all of pushover analysis loading steps.

Much of thank and appreciation for your help on this issue.

Have you tried assigning zero tension resistance to the material, as suggested in the Help System? If not, then please do, and let us know if it does the trick.

Seismosoft Support

Due to your recommendation by assigning zero tension resistance to the con-FRP material, I accomplished it.

I set ULTIMATE TENSILE STRAIN (m/m) for con_frp Material equal to zero, but it just delayed the divergence to a higher value of target displacement, and eventually it divereged.

Please give a another soultion to converge my problem.
Much of appreciation.

'Ultimate tensile strain' is not tension resistance. Our suggestion (and that of the Help System) is for you to render equal to zero the value of tension resistance of the existing concrete (modelled with con_cc).

Seismosoft Support

As you had recommended, I changed TENSILE STRENGTH of the con_cc to zero from its default value of 3000 kPa. But not only it didn't work out, but also it divereged at a lower target displacement.

I also want to highlight that I'm using con_frp material and assigning it to coulmns, how is it possible to influence the results by changing the TENSILE STRENGTH of the con_cc to zero? Because I'm just applying con_frp for columns. In previous version I didn't have any problem, but I encountered this problem in the newly released version.

Dear Mostafa Fakharifar,

Thank you for your detailed responses. Here's our feedback:

1) beams are connected, and in equilibrium, with the columns. Hence, when one changes the response of the columns (through FRP confinement) one will also modify the demand imposed on the beams, this being the reason why we suggested the change in the beams material.

2) we have tried to run your model, and experienced the same problems that you described initially. However, when we changed the parameter 'Ultimate tensile strain' to zero, the analysis ran fine. (we will send you the results file via email)

3) at this stage, it is difficult for us to establish what may be the cause of your problems, since, we repeat, the analysis runs fine on our computers. We would perhaps simply suggest that you enforce that the default settings are being used (Settings -> Program Defaults), and see if things change.

Let us know. Thanks again.

Seismosoft Support

In order to get converged results out of pushover analysis for a 2D, 8-Storey RC frame with conined frp column sections, I've done following steps due to your guidance:

1- first changing program settings to defaults==> It didn't change the result.

2- Changing "Ultimate Tensile Strain" for con_frp to zero and setting "Tensile Strength" for con_cc to 3000 kPa worked out. The analysis diverged at 0.41 m target displacement.

3- This option resulted the best results. Changing "Ultimate Tensile Strain" for con_frp to zero and also setting "Tensile Strength" for con_cc to zero as well. The analysis diverged at 0.74 m target displacement.

Now I'm doing pushover analysis for 4, 8, 12 and 16 storey 2D, RC frames with different patterns of frp confinement. I would surely leave my results in here to be a little bit of help for others.

Glad to hear the analysis now works.

We actually believe that loading the program's default settings has made all the difference (you had previously tried changing the tensile capacity to zero, and that did not solve your problems), and thus recommend it to all users.

The Forum does not allow for files to be uploaded, hence it will not be possible for you to post your results here. In any case, we do not feel that to be necessary; this discussion alone is already in itself very useful for others.

Seismosoft Support