Probabilistic nonlinear response analysis of steel-concrete composite beams

This paper employs a methodology for probabilistic response analysis based on the First-Order Second Moment (FOSM) method in conjunction with response sensitivity computation through the Direct Differentiation Method (DDM), to study the variability of the structural response of steel-concrete composite (SCC) beams. This methodology is applied to compute the first- and second-order statistical moments of the response of two actual structural systems for which experimental data are available. The results of the DDM-based FOSM method are compared with the experimental measurements and with the results of the computationally more expensive Monte Carlo Simulation (MCS) method. Different modeling hypotheses for the material parameter uncertainty are considered. It is found that the DDM-based FOSM method agrees very well with the MCS results, for low-to-moderate levels of response nonlinearity under low-to-moderate material parameter uncertainty, and up to high level of response nonlinearity under low material parameter uncertainty. It is shown that the DDM-based FOSM method is able to correctly describe the effects of random spatial variability of material parameters.