Study On Seismic Behavior Of Hybrid High Strength Steel Frame Joints

At present,the research object of the high strength steel structure is mainly aimed at the high strength steel composite eccentric braced frame,but the research on the performance of the bent steel frame is not enough.The reasonable mechanism of bending steel frame under the strong earthquake as "strong column weak beam",the mechanism not only by increasing the size of column and reduced beam section size is achieved,a more reasonable way is using high strength steel columns,steel beams with low strength,and the formation of new hybrid high strength steel frame structure.However,the steel frame beam column joints performance plays an important role in steel frame stress,not only affects the internal force distribution,stiffness,deformation,seismic performance of steel frame of the ductility and energy dissipation capacity plays a key role.In order to study the seismic performance of the hybrid high-strength steel frame joints,the finite element analysis and the low-cycle reciprocating loading test of the hybrid high-strength steel frame joints are carried out.The failure modes and main seismic performance of the joints are studied.And the correctness of the finite model is verified according to the test results.The parameters of the hybrid high strength steel frame are analyzed.In this paper,the mechanical properties of the four kinds of steel joints are studied,and the yield strength,ultimate strength and other mechanical properties are obtained.According to the material test results of four kinds of steel joints under static finite element analysis,the analysis results show that the influence of static performance of steel strength grade of hybrid high strength steel joints,joints with low strength steel,its stiffness and high bearing capacity,good ductility and static,high strength steel flange and web local buckling will occur in advance,resulting in the decrease of bearing capacity,ductility;mixed high strength steel frame joint bearing capacity and ductility than ordinary steel frame joints;bearing capacity of beam flange width to thickness ratio of steel joints has a certain effect,the greater the thickness ratio,the bearing capacity is low,and the bearing capacity of the reserve capacity is reduced.On the basis of the static analysis of steel joints were tested under cyclic loading,the results show that the hybrid high strength steel frame joint bearing capacity and seismic performance of steel and ordinary nodes are similar,the hysteretic curve is full spindle type,hybrid high strength steel frame joints and not because the lower column section size and the seismic effect performance.In order to make up for the deficiency of the test,the finite element analysis was carried out on the steel joints,and the results were in good agreement with the experimental results.The analysis results show that the strength of steel beam lower hybrid steel joints fuller hysteresis curve,seismic performance indices of bearing capacity,ductility and energy dissipation capacity are improved;the worse than wide beam flange greater the seismic performance,strength of steel beam stiffness has little effect of degradation degree.According to the verified finite element model,discusses the influence of beam and column section size on the hybrid high strength steel frame joints seismic performance,results show that the appropriate section size was diminished,the bearing capacity of the node does not decrease the ductility and energy dissipation capacity is improved;the appropriate reduced beam flange width thickness ratio and web thickness ratio,the ductility of the joints obtained improved beam flange width thickness ratios is low,higher bearing capacity and initial stiffness,the web thickness is relatively low,the bearing capacity changed little,the initial stiffness was significantly reduced,the energy dissipation capacity increased slightly.