Study on seismic retrofit of structures using SPSW systems and LYP steel material

Abstract

Steel plate shear walls (SPSWs) have been shown to be efficient lateral force-resisting systems, which are increasingly used in new and retrofit construction. These structural systems are designed with either stiffened and stocky or unstiffened and slender web plates based on disparate structural and economical considerations. Based on some limited reported studies, on the other hand, employment of low yield point (LYP) steel infill plates with extremely low yield strength, and high ductility as well as elongation properties is found to facilitate the design and improve the structural behavior and seismic performance of the SPSW systems. On this basis, this paper reports system-level investigations on the seismic response assessment of multi-story SPSW frames under the action of earthquake ground motions. The effectiveness of the strip model in representing the behaviors of SPSWs with different buckling and yielding properties is primarily verified. Subsequently, the structural and seismic performances of several code-designed and retrofitted SPSW frames with conventional and LYP steel infill plates are investigated through detailed modal and nonlinear time-history analyses. Evaluation of various seismic response parameters including drift, acceleration, base shear and moment, column axial load, and web-plate ductility demands, demonstrates the capabilities of SPSW systems in improving the seismic performance of structures and reveals various advantages of use of LYP steel material in seismic design and retrofit of SPSW systems, in particular, application of LYP steel infill plates of double thickness in seismic retrofit of conventional steel and code-designed SPSW frames.