Seismic design of steel structures with buckling-restrained knee braces

Analytical models and a performance-based seismic design procedure were developed for a structure with buckling-restrained knee-braces. The hinge-connected main structural members, such as beams and columns, were designed only for gravity loads, and the knee-braces were designed to resist all the lateral seismic load. The cross-sectional size of knee-braces was estimated using the equivalent damping required to be supplied to meet a given performance objective. Parametric study was performed with design variables such as slope and yield stress of the braces. According to the time-history analysis results of a five-story structure with buckling-restrained knee-braces, the maximum displacement of the model structure turned out to correspond well with the desired target displacement after it is retrofitted by knee braces following the proposed procedure.