Design and Performance Tests of Buckling Restrained Braces for Seismic Retrofit of a Long-span Bridge

ABSTRACT: Described in this paper is a retrofitting method of long-span bridges using a buckling restrained bracing, BRB, with the emphasis on the reduction of the weight during the retrofitting and its mechanical characteristics including the effect of the hysteretic damping are discussed. Five types of BRB members are compared: one uses the flat plates while the other uses crucified plates as the core member. In addition to these types, the third type is also considered by using the existing member with an intentional cut and with a buckling restraining sleeve. In the tests, models of the scale factor of 1/6 were made and they were subjected to repetitive tests to find the load-displacement relationship, hysteretic damping effect, yielding strength and the stiffness. From the test results, different characteristics were observed among different types of specimens. Furthermore, BRBs incorporated into a frame were tested in order to confirm the same damping performance as unit tests