A novel plastic-mechanism-based approach for determining the coupling degree in coupled steel plate shear wall systems

Abstract

A reliable evaluation of the degree of coupling (DC) is essential for understanding the seismic behavior and design performance of coupled steel plate shear walls (CSPSWs). Existing analytical approaches may exhibit reduced accuracy, particularly for highly coupled systems because the static equilibrium equations, precise geometric characteristics of structural members, and realistic plastic hinge locations are not explicitly considered. This study proposes a new plastic-mechanism-based analytical framework for evaluating the DC of CSPSWs. The proposed formulation incorporates the clear dimensions of coupling beams, horizontal boundary elements, and steel infill plates, together with the actual locations of plastic hinge formation, and fundamentally reformulates the static equilibrium equations. In addition, a simplified method based on vertical flexural deformation (VFD) is introduced for approximate estimation of the coupling degree. To validate the proposed methods, six prototype CSPSWs were designed according to AISC 341–22 provisions, and six additional specimens from previous studies were also investigated. Comprehensive nonlinear static pushover analyses were performed using ABAQUS. The results demonstrate good agreement between the proposed analytical equations, numerical simulations, and the VFD method. Compared with existing formulations, the proposed approach provides more consistent predictions for both weakly and highly coupled systems. For the six-story prototype configurations investigated in this study, a target DC range of 0.8–0.9 provides a favorable balance between structural efficiency and structural weight. This range is considered indicative for the investigated configurations rather than a universal design recommendation.