The Seismic Performance Analysis Of Buckling Restrained Braced Steel Frame With Semi-rigid Connections

Braced steel frame with many advantages such as light weight, high strength, good ductility, good lateral resistance ability and so on, so it is widely used in seismic system. In the traditional design and analysis of steel frame, the beam-column joints are usually assumed to be completely rigid connection or the ideal hinge connection, but the beam-column connections are actually in a semi-rigid connection status. Buckling restrained brace is a new kind of supporting member, which can improve the buckling behavior of ordinary brace under compression and has a good hysteretic and energy dissipation performance. Combining the advantages of semi-rigid connections and buckling restrained braces, buckling restrained braced steel frame with semi-rigid connections has a superior seismic performance. In order to further study the coordinated working performance between them, this paper conducted the following researches:Firstly, pushover analysis was conducted to semi-rigid steel frame with ordinary braces and buckling restrained braces by SAP2000. The influence of connection stiffness and braces on seismic performance was summarized. By observing the development of the plastic hinge, the seismic performance of structure was evaluated.Secondly, based on the seismic design method of buckling restrained braced steel frame with rigid connections, the paper proposed a design method based on rigidity ratio that is suitable for buckling restrained braced semi-rigid connections steel frame and then derived the range of the reasonable rigidity ratio of buckling restrained braced steel frame with semi-rigid connections.Finally, based on the five different rigidity ratio, the buckling restrained braces were setted up on three steel frames with different initial connection stiffness.And the effects of different initial connection stiffness and rigidity ratio on the structure were researched by nonlinear time history. Then, the paper picked out the cure of maximum displacement angle with rigidity ratio, identified the reasonable rigidity ratio of each model, and verified the reliability of the formula by comparing trial value with calculated value.