Research On Performance Of Separate Structural System Based On Variable Cross-Section Composite Beams

Research on steel structure system has an important significance, which improves the bearing capacity, seismic performance, economy of the steel structure building. In this paper, according to the material properties of steel and concrete and characteristics of the multi-stories and high-rise steel structure building, separate structural system is proposed based on variable cross-section composite beams. Separate structural system means the different resistance system independently resist the vertical load and the horizontal load, each resistance system respectively carry out the independent function, and functional division is clear. This paper mainly research on performance of variable cross-section composite beams and seismic performance of separate structural system.First of all, ANSYS was used to establish the finite element model to research on stiffness and bearing capacity under different span, different load form, different variable cross-section form, different variable cross-section wedge rate. The results show that the plastic zone in variable cross-section composite beams is larger which can fully use the strength of the material and have a good economy, comparing with the steel beams and ordinary composite beams. Comparing with ordinary composite beams, the stiffness and the ultimate bearing capacity of variable cross-section composite beams increase with the same volume of steel. The stiffness and the bearing capacity of variable cross-section composite beams have certain law, this paper provide a simplified calculation method.Then ANSYS was used to carry out seismic time history analysis, making comparative analysis on seismic performance of the separate structure and steel frame. The results indicate that under different earthquake, separate structure can effectively control the maximum lateral displacement and story drift ratio. Most of base shear in the earthquake was resisted by brace of the separate structure. Separate structure has better seismic performance comparing with steel frame.Finally, Push-over analysis was carried out on separate structure, getting target displacement and story drift ratio response, comparing with steel frame. The results show that, for the multi-stories and high-rise structure, the maximum lateral displacement and story drift ratio of separate structure has a great range decreased. Target displacement and story drift ratio with lateral vibration model loading mode is larger than uniform loading mode. Structure step into plastic under rare earthquake, through the distribution of the plastic hinge and the order, we can get the weakness points of structure which should be considered in seismic design.