Research On Seismic Behavior Of The New Buckling Restrained Brace Truss Infilled Steel Frame

Steel frame structure and shear wall infilled steel frame are two common lateral systems, but the rigidities of these two structural systems are substantially different. To realize the modulation of structural stiffness in a wide range, steel-concrete composite deep beams infilled steel frame as a new type of lateral resisting system is proposed. Composite deep beams are composed with steel plate and precast reinforced concrete slab which connected by high strength grip bolt. The lateral precast reinforced concrete slab can effectively prevent buckling of steel plate, and help developing plastic property as well as increasing the energy-intensive capacity. But the further research shows that, The plastic of steel plate in deep beam develops unbalancedly. Which means that the plastic of edges of steel plate fully developed while central area didn’t. When structure damages under cycle loading, the composite deep beams withstand lateral force by tension field, so the force model can be simplified as diagonal two-force rod model.The new buckling restrained brace truss infilled steel frame is put forward. The layout and function of the truss infilled the structure is similar to the composite deep beams infilled the steel frame. The parallel-chord truss infilled the steel frame can be considered as to turn the parallel-chord roof truss 90 degrees in its plane, and then connect the upper and bottom members with the upper and bottom beams of the steel frame with fillet weld. The original deep beams subjected to bending and shear deformation are transformed into tension and pressure of two-force rod in truss, and the force of structure is more reasonable. It also solves the unbalanced plastic development of composite deep beams. The web of the truss can be buckling restrained brace, which make the truss be truss of energy dissipation and improve energy dissipation capacity of the structure.Firstly,this paper analyzed the domestic and foreign research status of members infilled steel frame and introduced the proposed process and composition of the truss infilled steel frame. Based on this, 9 layers of steel frame and 4 different types of web member truss infilled steel frame models were built with SAP2000. The paper analyzed the above mentioned five models using modal analysis, time history analysis and Pushover analysis. The analysis showed that truss infilled steel frame can greatly improve the stiffness and bearing capacity, effectively limiting the lateral displacement. The truss in the truss infilled steel frame was the first line of seismic resistance in earthquake and the truss could improve the seismic behavior of the structure. By comparing the results of the analysis, the cross truss infilled steel frame and herringbone truss infilled steel structure got better seismic behavior than others. Next then, the optimizated truss structure filled with buckling restrained brace. The common truss infilled steel frame and the buckling restrained brace truss infilled steel frame were analyzed with response spectrum method and time history analysis. The result showed that the core of buckling restrained brace began to yield instead of buckling in the plastic stage. It consumed earthquake energy. The overall stiffness of structure was reduced as well as the seismic response. The buckling restrained brace truss infilled steel frame got a better seismic behavior than the common truss infilled steel frame. Lastly, yield stiffness ratio and elastic stiffness were analyzed with variable parameter. The analysis of yield stiffness ratio should be 0.01-0.05. The analysis of elastic stiffness showed that the structure can be optimized to limit the lateral displacement capacity and energy dissipation capacity by changing the elastic stiffness.