Hi, I’m trying to model an RC beam with cyclic load (first load until crack, unload, load again and so on) with material nonlinear effect. I started off with Star2 but realized afterward that unloading is not supported. An alternative is ASE, but I am still struggling to even make the beam act nonlinearly even the first step loading stage. I used loop with syst prob nonl with PLC as the last load case of each loop, and with NSTR (which I tried several options but still doesn’t work). The commands loook like this:

SYST PROB NONL PLC #lc0+#i-1
NSTR kn KSV pL

Is there anything I’ve done wrong? Also, is the cyclic loading analysis possible in this ASE module?

As far as I now you can do apply only monotonic loads in one load step when you use non-linear beams in ase.
However you can analyse cyclic loadings in TALPA using fiber-beam. Unfortunatly it is only for 2D frame structures.

Thank you. I will look into some work around then. But apart from cyclic loading, material non-linear beam should be possible in ASE, right? I still cannot get that part right, do you have any suggestions?

Also if you need nonlinear anylsis in 3d and your sections are rectangular you can use quad elements to model your beams. Quads supports nonlinear anaylsis in steps, also cyclic loading should be possible.

Thank you. I am actually using quad element but I also need beam to model discrete prestressing tendon. So I guess I wouldn’t be possible in this case. Thank you anyway

Wow thanks a lot, I never knew that. One more question if you don’t mind, if I have non-rectangular sections (eg. I section or Box girder), is it still possible to model if quad elements? In-plane bending with reinforcement/tendons doesn’t seem to work for me.

You can model a box by quads, but for every element (webs, flanges) have to be meshed area, so there will be a lot of elements which will be very time-expensive for calcuate in non-linear analysis.