SEISMIC PERFORMANCE OF ECCENTRICALLY BRACED FRAMES DESIGNED ACCORDING TO CURRENT CANADIAN SEISMIC PROVISIONS

摘要

Eccentrically braced frames (EBFs) have been widely used to resist wind and earthquake loads. Combining the excellent ductility of the moment resisting frames leading into large energy dissipation and the high elastic stiffness of the concentrically braced frames allowing resistance against lateral loads, make this system viable in moderate and high seismic regions. In EBF, the link element acts as the ductile fuse of the system keeping remainder of structure essentially elastic. However, poor design of the links, stiffeners and connection details may lead to inefficient performance of eccentrically braced frame under extreme earthquake loading. This paper studies performance of eccentrically braced frames designed according to current Canadian seismic design guidelines in CSA S16-09. A nonlinear finite element model is first developed. The finite element (FE) model includes both material and geometric non-linearities. The FE model is validated through comparing the finite element analysis results with the corresponding results from a quasi-static test. Finally, nonlinear seismic analyses as well as pushover analysis are conducted to study the performance of a four-storey eccentrically braced frame designed according to current CSA S16-09.