Cyclic experimental and analytical studies of buckling-restrained braces with various gusset connections

Five buckling-restrained braces (BRBs) with various gusset connections, including pinned gusset connection, bolted gusset connection, welded gusset connection, pinned-welded gusset connection as well as pinned-bolted gusset connection, were designed and tested under axial cyclic loading. Typical failure modes for all specimens were summarized and analyzed. The experimental results showed that all specimens exhibited stable hysteretic performance, good ductility and cumulative plastic deformation capacity. In addition, the relationship between the core plate strain demand and the effective factor was adopted to assess whether a BRB deformation satisfied the requirement of at least two times the design story drift. On the basis of Whitmore section and effective length, a formula of equivalent stiffness for a BRB with various gusset plates was suggested and verified by the experimental and numerical results. Furthermore, the finite element (FE) models of BRBs with various gusset connections were established and good consistency between the numerical and test results indicated that the FE modeling could simulate the cyclic behavior of BRB well. The elastic stiffness of gusset plate should be considered in the BRB design, and various gusset connection type and corresponding configurations provided an alternative method for designers to adjust conveniently the equivalent stiffness of brace under the premise of meeting the core plate strain demand.