Steel plate shear walls with outriggers. Part II: Seismic design and performance

Having investigated the plastic behavior and mechanisms of steel plate shear walls with outriggers (SPSW-O) introduced in Part I, it was shown that such systems are considerably effective in improving the flexural stiffness of conventional SPSWs. This paper describes procedures for the efficient design of SPSW-Os employing the principles of plastic analysis and capacity design. While the primary motivation behind the use of SPSW-O configuration is to enhance the overturning stiffness of SPSWs and provide architectural flexibility, the rigidly connected outrigger beams introduce additional lateral force resistance to the system due to the frame action, which must be taken into account for an efficient design. As such, this part of the analytical investigation focuses on quantifying the contributions of the tension field action of the infill panels and moment-resisting action of the SPSW boundary frame and/or outrigger frames to the global strength of the four SPSW-O options discussed in part I. The proposed approach together with the knowledge generated in part I are utilized in developing efficient design procedures for the SPSW-O systems. Then, the proposed procedures are used to design 12- and 20-story case study buildings having four different SPSW-O options as their seismic force resisting systems. Additionally, two SPSWs without outriggers, herein referred to as free-standing SPSWs, are also designed for comparison purposes. The seismic performances of the prototype SPSW-Os are evaluated using nonlinear static and response history analyses, and are compared with those of the free-standing SPSWs.