Buckling behavior of the core plate on buckling-restrained braces

The buckling-restrained brace has a core plate that is stiffened with a restraining part to prevent buckling. In practice, however, a high-order buckling mode occurs in the core plate when the buckling strength of the core plate is approximately equal to the yield strength of its cross-section. The results of testing of buckling-restrained braces conducted by the authors indicate that in the final phase of the testing, local deformation occurs in their core plates. At this point, their load-bearing capacity often starts to decline. In order to understand all the details of the mechanism of buckling observed in the core plates, which more specifically is, how the high-order buckling mode develops into local deformation in some core plates, the authors conducted strain measurement using strain gauges attached to core plates and analyzed the obtained data. The authors also established the relationship between the high-order buckling mode and the performance of the core plate including the energy absorption rate.