Question:
Can I simulate the cracked state of a concrete cross-section for a bending beam with the "Isotropic Nonlinear Elastic 1D" material model?
Answer:
No, the "Isotropic Nonlinear Elastic 1D" material model is not suitable for a bending beam, because the nonlinear stress distribution over the height of the cross-section cannot be modeled here. The reason for this is that there are no stress points/FE mesh points over the height of the cross-section. Thus, it is not possible to simulate the cross-section cracking.
On the other hand, the "Isotropic Nonlinear Elastic 1D" material model would be suitable for a cracking of the entire cross-section subjected to a pure axial force loading, but not for bending and compression.
For the simulation of a cross-section subjected to bending in the cracked state, we recommend performing a nonlinear analysis with RF‑CONCRETE Members and the RF‑CONCRETE NL module extension. Creep and shrinkage can be considered using the module extension in RF‑CONCRETE Members.
After the calculation, the nonlinear stiffness of the cross-section can be imported back into RFEM (see Image 01) and the internal forces can be determined again, taking into account the cracked concrete cross-section.
You can find more details about this procedure by clicking the following links:
https://www.dlubal.com/en-US/support-and-learning/support/faq/002881
https://www.dlubal.com/en-US/support-and-learning/support/knowledge-base/000992