As a new alternative design, plate-reinforced composite (PRC) coupling beam achieves enhanced strength and ductility by embedding a vertical steel plate into a conventionally reinforced concrete (RC) coupling beam. Based on a nonlinear finite element model developed in the authors' previous study, a parametric study presented in this paper has been carried out to investigate the influence of several key parameters on the overall performance of PRC coupling beams. The effects of steel plate geometry, span-to-depth ratio of beams, and steel reinforcement ratios at beam spans and in wall regions are quantified. It is found that the anchorage length of the steel plate is primarily controlled by the span-to-depth ratio of the beam. Based on the numerical results, a design curve is proposed for determining the anchorage length of the steel plate. The load-carrying capacity of short PRC coupling beams with high steel ratio is found to be controlled by the steel ratio of wall piers. The maximum shear stress of PRC coupling beams should be limited to 15 MPa.

Many existing deep reinforced concrete coupling beams that have low span-to-depth ratios are not desirable for seismic design due to their potential brittle failure with limited ductility and deformability. Previous experimental and numerical studies have demonstrated that the laterally restrained steel plate retrofitting method could effectively enhance the seismic performance of deep coupling beams. This article aims to develop a nonlinear finite element model based on the OpenSees software to accurately predict the behavior of coupled shear walls with or without laterally restrained steel plate coupling beams. The numerical results reveal that the seismic performance of the laterally restrained steel plate retrofitted coupled shear walls can be significantly enhanced. Furthermore, a genetic algorithm is adopted to determine the optimal positions of laterally restrained steel plate coupling beams. It is found that desirable seismic performance can be achieved by retrofitting coupling beams in the middle and higher floors of a building with coupled shear walls. However, only retrofitting coupling beams on the lower floors should be avoided because this could result in the serious degradation of the lateral load-carrying capacity and stiffness of the coupled shear walls.

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