State of the art of buckling-restrained braces in Asia

This paper presents a summary of buckling-restrained braces (BRBs). BRBs show the same load-deformation behavior in both compression and tension and higher energy absorption capacity with easy adjustability of both stiffness and strength. Research and developments of various types of BRBs with different configurations in Asia, especially in Japan, are introduced. Analyses and experiments are illustrated to show the conditions necessary for restraining steel braces from buckling. Some key issues of BRB configurations, such as gap and debonding processing between core braces and encasing members, contraction allowance in BRBs and necessary clearances between restraining panels and surrounding frames, BRB projection stiffening approaches to prevent it from buckling, are also described. Based on initial deflections of core braces, both stiffness and strength requirements of encasing member to prevent buckling of core brace are given. Applications for both new high-rise steel buildings and the seismic retrofit of existing buildings show good prospects of using BRBs.