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-order 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. 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. The DDM-based FOSM method is shown to correctly describe the effects of random spatial variability of material parameters. (C) 2013 American Society of Civil Engineers.