Bending Capacity of Steel-Concrete-Steel Composite Structures Considering Local Buckling and Casting Imperfection

Abstract

Steel-concrete-steel (SCS) composite structures with bidirectional steel webs and ribs exhibit superior performance in capacity, rigidity, ductility, blast resistance, waterproofness, and construction efficiency compared with traditional engineering structures, making them especially suitable for megaprojects, such as submarine tunnels, nuclear shells, and offshore structures. The current design method is mainly an adaptation of reinforced concrete code, and studies to investigate the distinctiveness of the structure considering the composite action are needed. Seven bending tests were conducted and numerical models developed to study the bending behaviors of SCS composite structures. The major concerns were local buckling behavior and casting imperfection, which are rarely studied but of importance in practice. It was found that the biaxial strengthening effect due to lateral constraint plays an important role and should not be neglected especially in the tension flange, which typically offers an enhancement of about 15% in strength at the ultimate state. Based on the experimental, numerical, and theoretical analyses, suggestions are proposed to modify the current design method which clarify construction requirements considering local buckling and casting imperfection. These modifications have been proven to provide approximately 10% improvement compared with the experiments.