Dear my friends
I modeling a concrete connection in Ansys Mechanical APDL,that picture’s attached. In this model the column was subjected to a constant axial load equal 305 Kn and monotonic displacement applied to the tip of beam. Solid65 element used for concrete ,link180 used for longitudinal bars. Nonlinear concrete mode used for concrete material(without crushing option) with miso model . i set Force and displacement convergence criteria with 0.025 tolerance for force , and 0.25 for displacement criteria.
The problem is that my model do not converge if there are axial force !!!!
also when the cracking occurred solution not converge!!
what’s your idea about this problem ?
I can share my model for control it.
Best regards.
behzad.
You will get a convergence problem when the solution enters a highly nonlinear stage, i.e., usually when the model fails. That is expected.
Hello,
The problem may be due to the selection of key option for SOLID65 element or the applied boundary condition. Try using KEYOPT(7)=1 for SOLID65 element to include the stress relaxation after the cracking which will also helps in the convergence by taking a constant tension stiffener multiplier and KEYOPT(8)=1 to suppress the total crushing warning. The crack Also, check your boundary condition and contact between the beam and column.
Follow the ANSYS theory manual for detail about the modeling of crack.
http://www.ansys.stuba.sk/html/elem_55/chapter4/ES4-65.htm
I have this problem too . I put a small load so my model doesn't experience nonlinear stage and I also set KEYOPT(7) and KEOPT(8) to one , but nothing differs .
I hope if you have found a solution... to send me thankfully.
YAssin Allahham
SOLID65 has a well know relation with concrete material in ansys APDL/workbench (through commands). however the convergence issues associated with SOLID65 element and the mesh sensitivity of the CONCRETE/SOLID65 combination was one of the motivations for moving to the Microplane model that tracks the softening behavior of the concrete as it fails, without having to track individual cracks. The microplane model with a newer CPT215 element delivered Force - Displacement results that had no significant mesh sensitivity, and agreed very well with the experimental data. A Technology Guide shows how to use the Microplane model with the CPT215 element. Find the youtube video link below (in Russian language). They are comparing the results of the old method using SOLID65 with the new micro-plane model with current technology elements.
youtube link: https://www.youtube.com/watch?v=Vb-xVXdY3Go&t=382s
YOU CAN DROP YOUR FORCE CONVERGENCE 0.025, AND ONLY CONSIDER THE DISPLACEMENT CONVERGENCE OF =0.025 IN THE NON LINEAR STAGE THAT IS FROM FIRST CRACK OR SIMPLY FOR THE WHOLE ANALYSIS YOU CAN DROP YOUR FORCE CONVERGENCE, OR YOU CAN USE FORCE CONVERGENCE UPTO LINEAR STAGE ONLY, ONLY NON LINEAR STARTS THEN DROP FORCE CONVERGENCE.
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