Nonlinear FE Analysis of Steel-Concrete Composite Structures

Abstract

This paper presents an advanced nonlinear finite-element (FE) program developed for the analysis of general composite structures of steel and reinforced concrete, including composite space trusses. The elements used to represent the concrete slab and steel beam actions are described, and in particular the ability to model ribbed composite slabs of reinforced concrete on profiled steel sheeting is demonstrated. Attention is drawn to the usefulness of the layering technique in determining local stress redistributions associated with progressive through-depth cracking and yielding in the slab and steel beam elements. Concrete is represented as a nonlinear elastic isotropic material before cracking and nonlinear orthotropic thereafter, while steel is taken to be initially elastic with strain-hardening capabilities after yielding. All material models are empirical in origin. A specialized stub element with empirical nonlinear shear force-slip relationships is used at the concrete slab–steel beam interface to permit modeling of either full or partial shear connector action. Results obtained from the use of the program, including predicted crack patterns, are shown to compare very well with those from experiments on reinforced concrete slabs and steel-concrete composite structures up to failure.