Study On Seismic Behavior Of A New Type Of Buckling-Restrained Braces

For the character of Buckling-restrained braces (BRB) that will not buckle under compression other than yield, buckling-restrained braced frame (BRBF) have better energy dissipation characteristics than the conventional braced frame (CBF). The microcosmic mechanics model and macroscopical mechanics theory of BRB are studied. Geometrical condition and physical condition when BRB is buckled with high level are identified, which the following experimental studies of BRB are based on. This paper is foucs on experimental tests of a new type BRB which are shown as following:(1) Six BRB specimens were tested with cyclic loading history including standard loading history and low-cycle fatigue loading history. The test results indicate that the measured mechanics properties indexes of BRB including elastic stiffness, secondary stiffness agree well with theoretical results and the energy dissipation behavior of BRB is stable. This new type of BRB can meet the requirement of existing norms and reach the standard of application.(2) A steel plane buckling-restrained braced frame (BRBF) and a conventional braced frame (CBF) were tested with cyclic loading history. The test results indicate that the hysteresis curve of BRBF is full and the seismic behavior of BRBF have been improved because the better energy dissipation of BRB. And BRBF also has better stability and energy dissipation characters than CBF.(3) A steel BRBF was tested on shaking table. The test results indicate that BRB and the frame are in elasticity and BRB can give frame stability and stiffness when PGA is less than 0.6g. The test results also indicate that BRB is in elastic-plasticity while the frame is still in elasticity when PGA is more than 0.8g.