Seismic behavior and design of boundary frame members in steel plate shear walls
Steel Plate Shear Walls (SPSWs) consist of infill steel panels surrounded by columns, called Vertical Boundary Elements (VBEs), and beams, called Horizontal Boundary Elements (HBEs). Those infill panels are allowed to buckle in shear and subsequently form diagonal tension field actions to resist the lateral loads applied on the structure. Research conducted since the early 1980s has shown that this type of system can exhibit high initial stiffness, behave in a ductile manner, and dissipate significant amounts of hysteretic energy, which make it a suitable option for the design of new buildings as well as for the retrofit of existing constructions. However, some obstacles still exist impeding more widespread acceptance of this system. For example, there remain uncertainties regarding the seismic behavior of boundary frame of SPSWs. This dissertation reports on a research program conducted to investigate the behavior of boundary frame members of SPSWs. First, a two-phase experimental program was developed to test a two-story SPSW specimen. The testing program also investigated how to replace the infill panels of the SPSW after a severe earthquake and how the repaired SPSW would behave in a second earthquake. Analytical studies using both a simple model (called the dual strip model) and 3D finite element (FE) model were conducted to replicate the observed SPSW behavior. Next, new analytical models were proposed to calculate the HBE plastic moment accounting for the reduction in strength due to biaxial internal stress conditions, and to develop improved capacity design procedure for HBEs accounting for these reduced plastic moments of HBEs. These advances make it possible to investigate and explain the observed intermediate HBE failure. Furthermore, the adequacy of a flexibility limit for VBE design specified by the current design codes was assessed using new analytical models developed to prevent the undesirable in-plane and out-of-plane performances of VBEs. Finally, a SPSW design procedure accounting for the contribution of boundary frame moment resisting action was proposed.