Improving Overturning Stiffness of Steel Plate Shear Walls

Steel Plate Shear Walls (SPSWs) are efficient and economical energy dissipating systems for buildings located in regions of high seismic risk. In spite of many benefits of SPSWs, however, their overturning stiffness is relatively low, especially in mid-to-high rise buildings. Therefore, there is a need for incorporating other structural elements in conjunction with such systems to resist high overturning moments resulting from lateral loads. A logical solution that can be effectively used in SPSW systems is to rigidly connect the girders of adjacent bays to the columns of SPSWs (on both sides) forming an interacting system of shear wall and moment frame in which the adjacent girders act as outriggers to reduce the overturning moments in the SPSW. However, insufficient information exists on behavior and efficiency of such structural system, herein referred to as SPSW with Outriggers (SPSW-O). As part of a comprehensive research project on SPSWs being conducted at the University of Alberta, this paper describes different potential SPSW-O options and discusses their effectiveness in improving the flexural stiffness of the system. The performance of these options is evaluated for 20-story SPSW-O systems using nonlinear static and response history analyses.