Seismic Analysis On Buckling Restrained Braced Steel Frame And Research On Its Structural Influencing Coefficient

The steel structure is light-weight and high-strength and have good seismic performance. The beam and column sections of non-braced steel frame are usually amplified to satisfy the lateral displacement because of its flexible lateral stiffness.The center-brace is always buckling under strong earthquake which makes the lateral stiffness and dissipation ability of the frame fall down rapidly.The eccentric-braced flame has resolved the problems appearing on above-mentioned structures to a certain extent but the eccentric-brace is still buckling under massive earthquake and have an asymmetric hysteretic behavior under tension and compression.In order to improve mechanical performance of brace, a new system called buckling restrained braced steel frame is put forward, This system has been adopt in developed nations and domestic application research is in continuous evolution.At first,the buckling restrained braced steel frame and ordinary concentrically braced steel frame are simulated adopting ANSYS in this paper. The results show that hysteretic curve of buckling braced steel frame is plumper than conventional concentrically braced steel frame. The area of hysteretic loop is bigger, which indicate that it can dissipate much more energy, and has more strong energy-dissipating capacity.Time history analysis was performed on the buckling restrained braced steel frame and ordinary concentrically braced steel frame, time-history response on the big and small earthquake of the two systems are contrasted. It shows that seismic behavior of buckling restrained braced steel frame is better.Based on incremental dynamic analysis, structure base shear and top displacement are calculated and polynomially fitted, and the IDA ability curve is obtained,based on which, the influence of the number of story and span to structural influencing coefficient of buckling restrained braced steel frame is researched. The analysis shows that the influence of the number of story and span is so small that it can be neglected . The proportion of over-strength coefficient of structure in the structural influencing coefficient R is much bigger than that of ductility coefficient.