Cyclic Performance of Braces with Different Support Connections in Special Concentrically Braced Frames

Abstract

Gusset plate connections between the steel braces and the supporting frame members play an important role in the performance of special concentrically braced frames (SCBFs) under earthquake loading conditions. Extensive studies have been conducted on SCBFs in which the gusset plate connections are designed to ensure the out-of-plane buckling of steel braces. However, research on the cyclic behavior of gusset plate connections allowing the in-plane buckling of braces is very limited. An experimental investigation has been carried out in this study to investigate the cyclic performance of the in-plane buckling of gusset-brace assemblies. Tests showed that the gusset plate connections detailed for in-plane buckling of braces provided performance at par with those detailed for the out-of-plane deformation arrangement. A numerical comparative study on three types of connection arrangements has also been conducted, namely, a) out-of-plane buckling of braces using gusset plates, b) in-plane buckling of braces using knife plates, and c) direct connection of braces without using any gusset plates. Braces made of hollow steel sections having constant slenderness ratio and width-to-thickness ratio are used in all the numerical models. The main parameters compared are the energy dissipation capacity, displacement ductility, patterns of failure, and the sequence of yielding in the components. Both test and analysis results are used to quantify the performances of gusset plate connections in order to achieve an efficient and reliable concentrically braced frame systems.