Seismic behavior and shear capacity prediction of coupled concrete-filled multicellular steel tube composite shear walls

In this paper, a coupled concrete-filled multicellular steel tube composite shear walls structure (CCSSW) is proposed. A finite element model (FEM) is developed to investigate the seismic behavior of CCSSW, and the model was validated by the tests. The effects of four parameters including axial compression ratio (ACR) on the hysteretic behavior of the CCSSW were studied. Then, a theoretical model for predicting the ultimate shear capacity (USC) of CCSSW was established. The results show that the failure mode of coupled walls exchanged from flexural failure to flexural-shear failure with increasing the ACR, and it is recommended that the ACR should less than 0.6 to ensure the ductility requirement. To better realize the function of the first line of defense of steel coupling beam (SCB), following recommendations are concluded: the span-to-depth ratio range of SCB is 4.0-6.0, the wall stiffness ratio is 2.4-4.7, and low yield strength material should be used for SCB. The maximum error on USC between FEM results and theoretical results is 12.8%, and most of them are less than 10%, indicating the effectiveness of the proposed theoretical model.