COMPRESSIVE-TO-TENSILE STRENGTH RATIO OF BUCKLING-RESTRAINED BRACES USING STEEL-AND-MORTAR PLANKS

A buckling-restrained brace (BRB) is composed of a steel core, which resists axial force, and a buckling-restraining system. A carefully designed clearance, often filled with unbonded material, is placed between the steel core and the restraining system to avoid force transfer between the two components through friction. Consequently, BRBs are able to provide stable hysteresis characteristics with the same strength in tension and compression. The authors have developed a new variation of BRBs that use steel-and-mortar planks for the buckling-restraining system. The key advantage of these BRBs is that quality control can be achieved easily. A large number of laboratory test results suggest that the BRBs using steel-and-mortar planks exhibit excellent performance on par with widely used commercialized BRB products. This paper reports recent findings from the research and development effort towards developing reliable and economic BRBs. The emphasis is on the buckling deformation of the steel core and force transfer between the steel core and the buckling-restraining system. Static, cyclic loading tests were performed on six BRBs using four different slenderness ratios for the steel core. The newl