Seismic performance of multistory CBFs with novel recentering energy dissipative braces

Abstract

For concentrically braced frames (CBFs) with conventional braces, although they can prevent collapse during earthquakes, people have to confront the costly repair work and long downtime induced business interruption, which is often attributed to excessive residual deformations. Shape memory alloys (SMAs) provide promising solutions to this problem. SMAs are gaining increasing favor by the community, owing to their excellent superelasticity which endows them with capabilities of recovering large deformation and dissipating input energy. Currently, the authors analyzed the seismic performance of CBFs with a novel brace termed recentering energy dissipative brace (REDB). The REDB is essentially a parallel combination of SMA bars and steel bending plates, the former primarily provides self-centering capability and the later is to enhance damping. This paper is to understand the seismic behavior of CBFs braced with REDBs, with an additional motivation to examine whether the REDBs can outperform the corresponding buckling-restrained braces (BRBs). Nonlinear static and time-history analyses are conducted for a prototype 6-story frame building. The corresponding results are compared against similar BRB frame. The basic comparison is made under the seismic scenarios associated with the design-basis earthquake hazard level. Through the comparative analysis, it is found that the properly designed REDBs are superior to the BRBs from the perspectives of generating identical demands in terms of maximum interstory drift ratios and maximum floor accelerations, and meanwhile eliminating residual interstory drift ratios. The confidence of the results is further gained by varying the seismic intensity and the assumed damping level.