Behavior and large-scale experimental testing of Steel Plate Shear Walls with Coupling

The Steel Plate Shear Wall with Coupling (SPSW-WC) configuration is an extension of the conventional Steel Plate Shear Wall (SPSW) seismic lateral force resisting system. The SPSW system is composed of a steel frame with web plates between the beams and columns. In North America, the web plates of the SPSW are typically slender and unstiffened and dissipate energy through yielding of a diagonal tension field. Architectural constraints often encourage the designer to place a pair of conventional SPSWs adjacently. The SPSW-WC configuration consists of linking a pair of SPSW piers together with coupling beams at the floor level. The SPSW-WC configuration retains many of the benefits of the SPSW system, such as high initial stiffness, good ductility, and the ability to dissipate a large amount of energy, while introducing another form of energy dissipation. Additionally, the SPSW-WC system achieves greater material efficiency than a pair of conventional SPSWs. However, limited research is available on the SPSW-WC configuration. Therefore, the purpose of this work is to present a comprehensive study of the SPSW-WC configuration as a seismic lateral force resisting system in high seismic regions. The conventional SPSW design procedure was extended for the SPSW-WC configuration. The design procedure was used to develop a suite of prototype structures. The fundamental response of the SPSW-WC configuration was explored through a mechanism analysis. Closed-form analytical expressions were derived based on the geometry and member sizes of a SPSW-WC frame for the ultimate strength and the degree of coupling, a parameter related to the proportion of the applied moment resisted by a vertical axial force couple in the piers. The prototype structures were analyzed using time history analysis under different levels of ground shaking. The performance of the SPSW-WC was compared with the conventional SPSW system. An experimental test program was developed to explore the response of the SPSW-WC with realistic fabrication techniques. Two half-scale specimens were constructed to represent the bottom three stories of two six-story prototype structures. The degree of coupling and the characteristic inelastic behavior in the coupling beams were the primary parameters that differentiated the two specimens. The specimens were subjected to a cyclic displacement protocol, with mixed-mode hybrid control algorithms used to emulate the demands on bottom three stories of a six-story structure. The experimental SPSW-WC specimens demonstrated robust cyclic performance that was consistent with the design intent. Both specimens reached 4% lateral drift, the maximum displacement that could be imposed by the facility, with minimal strength degradation. Additionally, a large amount of energy was dissipated during each test, with over 20% equivalent viscous damping observed in the 4% drift cycles. The web plates, horizontal boundary elements, and coupling beams all exhibited ductile response through large inelastic deformations. Numerical simulations of the experimental specimens accurately captured the global and local behavior observed in the laboratory. The numerical modeling approach used in this study is shown to be an accurate tool for evaluating nonlinear response of the SPSW-WC system. Furthermore, the assumptions in the design procedure were validated using the response of the experimental test program. The SPSW-WC configuration was shown to be a viable seismic lateral force resisting system for use in high seismic regions through analytical, numerical, and experimental exploration. A design procedure and supporting equations for quantifying fundamental system parameters have established a framework for proportioning SPSW-WC systems to achieve acceptable seismic performance. Therefore, this work provides the basis for implementation of the SPSW-WC configuration in standard design practice