Performance-Based Seismic Design Of Structure With Buckling-Restrained Brace

The displacement of high-rise steel frame is large under horizontal action for the flexibility, if braces are fixed, the stiffness and seismic behavior of frame are improved, however, conventional brace tends to buckling under compression, so it's better to replace conventional brace with buckling-restrained brace(BRB) which yields at whole cross section for the effect of constraint element. Rational designed buckling-restrained brace was the first to yield under sereve earthquake and the main structure was protected.Basic theory of mechanics of buckling-restrained brace was first introduced. Modeling and analysis of frame, conventional brace frame and buckling-restrained brace frame were realized by finite element software MIDAS, by comparing three types of frame, structure reaction under earthquake was obtained. The behavior of conventional brace and buckling-restrained brace are similar under frequent earthquake, frame with conventional brace or buckling-restrained brace tends to much smaller displacement than simple frame; the seismic behavior of buckling-restrained brace is much better than conventional brace under sereve earthquake, a good seismic reduction effect of buckling-restrained brace frame was gotton.Displacement-based seismic design for buckling-restrained brace frame was discussed, based on storey drift of simple frame under frequent earthquake and target displacement, the area and quantity of buckling-restrained brace were determined, then the designed buckling-restrained braces were calculated on account of energy structure absorbed under sereve earthquake. Pushover analysis showed that a good seismic performance and economy were obtained by means of method refered. 6 types of buckling-restrained brace frame models were analyzed by software MIDAS and seismic response under sereve earthquake were compared; besides, the cost of structure was estimated based on cost-benefit rules, and the optimization type of buckling-restrained brace frame was gotten after overall considersion.