| Special-shaped concrete-filled steel tubular column structure is a new structural system which combines special-shaped column structure with concrete-filled steel tubular structure.It has the advantages of two kinds of structures: special-shaped column(Tshaped,L-shaped and cross-shaped column)limb with the same thickness of filler wall,which has high space utilization rate with more regular indoor space,enhances the flexibility of architectural design and architectural aesthetics;Concrete-filled steel tubular structure has good seismic performance with strong bearing capacity,good deformation and energy dissipation capacity and it is easy to implement assembly construction.Based on the previous studies of the mechanical and seismic performance of special-shaped concrete-filled steel tubular columns and frame joints,in order to further perfect the structure system,the seismic performance of special-shaped concrete-filled steel tubular column to H-shaped steel beam frame(SCFSTF)is studied in this paper.The main research work and results are as follows:(1)Four SCFSTF specimens were designed,with two connection forms(exterior diaphragm connection and vertical rib connection).The failure process and failure mode were observed by pseudo-static hysteretic test.The seismic performance was analyzed from the aspects of hysteretic curve,skeleton curve,ductility,energy dissipation capacity,stiffness and strength degradation,stress,strain,beam-column rotation angle,deformation of the joint panel zone and failure mechanism.The axial compression ratio and connection forms are the key factors investigated.The test results show that the four SCFSTF specimens meet the seismic design requirements of "strong column-weak beam" and "strong joints".The energy dissipation capacity and ductility of the specimens are adequate,which proved its excellent seismic performance.Exterior diaphragm connection and vertical rib connection are both effective force transmission connections.(2)The finite element model of SCFSTF specimens were established by ABAQUS software and monotonically loaded,which was in good agreement with the test.The model can accurately predict the load-displacement skeleton curve,the failure mode of key parts and the hinge mechanism.The stress distribution law of the joint zone,exterior diaphragm,vertical rib and the tensile bar was obtained.(3)The fiber model of SCFSTF specimens were established by OpenSees software,and cyclically loaded,which were in good agreement with the test.The model can accurately predict the load-displacement hysteretic curve,skeleton curve,plastic hinge deformation and the hinge mechanism.According to the moment-curvature curves of beam and column ends,the position and sequence of plastic hinges were judged and the quantitative index of the development degree of plastic hinges was put forward.Based on the parameter analysis,the influences of concrete strength,steel yield strength,steel ratio of column section,column axial compression ratio,column slenderness ratio,beamcolumn stiffness ratio and beam-column flexural capacity ratio on SCFSTF hysteretic behavior were obtained,and the corresponding design suggestions were put forward.The influence of P-? effect and test device error on hysteretic behavior of frame was analyzed.(4)Two models of special-shaped concrete-filled steel tubular column to H-shaped steel beam space frame were established by ETABS,and pushover analysis of the selected plane frame was carried out by OpenSees.Based on the calculation results,the development laws of floor displacement,inter story drift ratio and plastic hinge corresponding to the performance points were obtained.The results show that the specialshaped concrete-filled steel tubular column to H-shaped steel beam space frame designed according to the codes and the actual engineering can fully meet the seismic fortification performance target of a “small earthquake is not bad,a medium earthquake is repairable,a large earthquake is not collapsed” in high intensity seismic area. |
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