The most accurate setting of material behavior diagrams in finite element modeling (FEM) determines the accuracy of reproducing the real mechanism of structural failure under load. Therefore, the aim of this study was to find the optimal type of diagrams that would consider the nonlinear component and the peculiarities of National Standards.

This study used statistical analysis of the steel design parameters and the deformation-iteration method to determine the curve of dependence between stresses and strains in concrete.

When performing FEM of composite steel and concrete (СSC) structures in the ANSYS software package, it was found necessary to consider the plastic deformation in order to more accurately reflect the actual behavior of composite sections, based on the physical and mechanical properties of the materials, which would correlate with the current codes. As a result, parametric values of key points of the plastic section of the concrete performance diagram were obtained, which made it possible to simulate the post-critical stage of СSC columns under static and dynamic loads.

The resulting diagrams provide an appropriate representation of the materials' nonlinear properties with an accuracy of 5–7%, allowing for a correct assessment of limit states and optimal design decisions in terms of safety and cost-effectiveness.

Further research will help gather enough statistical data to train the neural network, which will make it way easier to check and evaluate the results of experiments on СSC structures.