Stiffness analysis of concrete filled steel plate composite coupling beams

The structural performances, such as the internal force distribution, lateral stiffness, etc., of the coupled shear walls are mainly influenced by the stiffness of the wall piers and coupling beams. The stiffness of the concrete filled steel plate composite coupling beam is studied to provide the basis for the analysis of composite coupled shear walls. Based on the assumptions that the concrete infill and surface plates are deformed without relative deformations and the concrete tensile strength is equal to 0, the relationships between the internal forces and sectional deformations of the composite coupling beams without slip are established, and the stiffness formulae are deduced. It is found that the slip between the concrete infill and surface plates has great effect on the beam stiffness. The lateral stiffness of the composite coupling beams may decrease by 10% to 24% when slip is considered. The stiffness formulae of the composite coupling beams without shear connectors are proposed by introducing a reduction factor of 0.5 to the stiffness formulae of the ideal composite coupling beams without slip, which are verified to be accuracy by the finite element model and test results.