Numerical study of concrete-filled steel plate composite coupling beams

Abstract

Concrete-filled steel plate (CFSP) composite coupled shear wall systems consisting of two or more CFSP composite wall piers connected by CFSP composite coupling beams are efficient seismic resisting systems for high-rise buildings. A nonlinear finite element model that can simulate the load–deformation behavior and local response of CFSP composite coupling beams was developed to investigate their deformation and force mechanisms. Although the beam end rotation contributes largely to the lateral displacement in the initial loading stage because of local deformations at the connection regions, the flexural and shear deformations of the coupling beam are the main contributors when the coupling beam deforms into plasticity. The ratio of flexural to shear contributions to lateral displacement is affected significantly by the beam span-to-height ratio and ratio of steel flange thickness to web thickness. The effective sectional stiffness of CFSP composite coupling beams can be taken as the sum of the full stiffness of the steel plates and a reduced stiffness provided by the concrete infill. Because of the compression resistance provided by the diagonal compression strut formed in the concrete infill, the steel web plates tend to sustain tension forces, and shear forces are sustained mainly by the web plates in the compression region. For the common coupling beams, the steel plates resist 36–76% of the shear force, and 57–82% of the beam end moment, and the remainder of the internal forces is resisted by the concrete infill.