Reinforced concrete shear walls have a high out-of-plane stiffness, while the steel shear walls have a slight out-of-plane stiffness. To prevent the buckling, the steel plates are connected to the concrete panel by shear lugs (composite shear walls). In this paper, the behavior of coupled composite shear walls is investigated. The results show that the stresses created in the system of coupled shear walls are reduced in comparison to separate shear walls and that lateral stiffness is increased. However, increasing rigidity of coupled beams more than a specified amount does not significantly affect the elastic behavior of the system. Therefore, a relation that can approximate the the ideal coupled beam is suggested.
A dual system of steel moment-resisting frame and composite shear walls was designed, and static nonlinear analysis was performed. In the following, the composite shear walls are assumed to be unchanged, and the dimensions of the coupled beam are calculated by the proposed relationship and static nonlinear analysis has been performed. Comparison of the results shows that the resistance and seismic parameters of the coupled shear walls are more than separate shear walls. The studies show that increasing the rigidity of the coupled beams more than that of the ideal beams does not have a significant effect on the increase of the resistance parameters of the system and, moreover, the ductility of the system decreases. Therefore, the dimensions of the ideal coupled beam cross section are predicted well even in the nonlinear performance of the system.