Effect Of BRB Layout Scheme On Seismic Behavior Of Steel Frame Structure

While urban crowding, shortage of land and the fierce business competition, more and more high-rise buildings are around us. The use of frame structure in high-rise building is very common, and a frame structure with braces can effectively reduce the lateral displacement of the structure. However, under the action of strong earthquakes the braces may cause buckling, resulting in failure and destruction of the brace part and the effect in energy hysteretic dissipation will be greatly reduced, which will lead to the decrease of the seismic performance of the overall structure. In order to solve the problem of the buckling and the poor hysteretic performance of the general braces, foreign scholars presented a kind of buckling restrained brace device, which possesses excellent performance. The ability of the buckling restrained braces in resisting the strong earthquake is stronger,and after a strong earthquake occurred, buckling restrained braces can be easily replaced even if it may buckling badly, which doesn't affect the use of whole building.Considering the characteristics of staggered steel braced frame structures and buckling restrained braces, this paper presents a staggered buckling restrained braced frame structure layout system and has carried out the following work:(1) A new type of staggered buckling restrained braced frame structure is proposed, and the layout of the staggered buckling restrained braces in a frame structure is given. Besides, the relevant parameter selection methods needed in the design of buckling restrained braces are summarized. Based on the improved Bouc-Wen model's related formula derivation, the direct solving expression of approximate solution model by mathematical method is established, which without iterative procedure, don't need a range of convergence, and can calculate by hand to solve the equation.(2) Push-over analysis is conducted in no-braced, buckling restrained braced, staggered and general buckling restrained braced frame structures in different BRB layout scheme. Through the research for the plastic hinge developed trends and path, base shear-top displacement curve and capacity spectrum and demand spectrum curve of several different frame structure, the results show that the development of plastic hinges are almost similar for staggered and ordinary placed buckling restrained braced frame structures. Two improved placement types of staggered buckling restrained braces are suggested, which have good economic effect and seismic performance. The study verifies the feasibility of the staggered buckling restrained braced frame structures in the actual projects.(3) Different types of structures are designed, including no-braced, buckling restrained braced and staggered buckling restrain braced frame structures in different BRB layout scheme. The dynamic characteristics analysis and seismic elastic-plastic time history analysis are carried on for the five types of structures using SAP2000 software. The results are compared and analyzed. The numerical analysis shows the good seismic performance and the superior economic benefit of staggered buckling restrained braced frame structure system.