Ultimate Capacity Analysis of Concrete-Filled Steel Tubular Structure under Eccentric Compression

With the theory of updated lagrangian (U.L.) finite element formulation, the incremental equation of virtual work of a three-dimensional (3D) beam for a geometric non-linear analysis of the space structure is established. Material constitutive relation relationships, considering restriction effect, of both outer steel and core concrete, are proposed in the paper. Based on the nonlinear finite element method and fiber model, the whole load-deflection curves and ultimate bearing capacity of short and long concrete filled steel tubular (CFST) members under eccentric compression are presented and discussed. The efficiency and applicability of the proposed method are proved by comparison results. The members with larger eccentric distances have lower ultimate bearing capacity, but have better ductility.