Can anyone help me? I’m analyzing the stresses of a footing (concrete and rebar) using finite element analysis, but my result stresses are far inconsistent with the stresses in conventional analysis (beam theory). Actually, I have already used three FEA softwares (abaqus, ansys and prepomax), all of them have almost same stress results but still not in agreement with the conventional. Thank you very much.
I’m not a civil engineer but I’ll try to help. However, you’d have to share some details of your analysis for us to be able to help you. If you can’t attach the .pmx file (which would be the best option), please at least describe the details of the simulation and share some screenshots. It would be also good if you could post your analytical calculations for comparison.
Modeling RC in CalculiX is particularly tricky by the way. I wonder how you approached it.
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Thank you very much. Do you also know how to use Abaqus?
Yes, I work in Abaqus on a daily basis.
Stress distribution in concrete compression much depend on nonlinear material type selection. Analytical stress distribution commonly use simplification of compression block such as proposed by Whitney or any simple shape. It’s difficult to direct compares of both methods in stress and strain. Only in resultant force of concrete compression and steel tension could be possible to verify the assumption.
Since the purpose an analytical methods are to predict and estimate quickly by hand calculation at ultimate capacity based on empirical formulation derived from large test results, so a damage type material is required to reach a good results.
The case become more complex for analysis of footing, since it rest on the soil ground. Analytical approach use assumption of concrete footing in rigidly infinite were actually use soil-structure-interaction in nonlinear FE.
Maybe i can give some comment and suggestion, if you provide a problem sketch and description of FE models.