Seismic Experiments And Theoretical Studies On Endplate Joints For Semi-rigid Frames To Concrete Filled Steel Tubular Columns

Seismic experimental study and theoretical research on behavior of endplateconnection to semi-rigid concrete filled steel tubular (CFST) columns wereinvestigated in this paper, including theoretical and experimental studyes. Themain achievements were summarized in detail as follows:(1) A series of experimental study of four specimens of endplate connection toCFST column with blind bolts subjected to cyclic loading has been done,and themain parameters were the thickness of end plate and the column section type. Thefailure mode,the moment-rotation hysteretic curves and envelop curves, theregulation of degradation of strength and stiffness, ductility, and energy dissipationwere analyzed and evaluated through the experiment results and analysis.(2) The analytical models of endplate connection to CFST column with blindbolts under axial loading and cyclic loading were developed by finite elementanalysis (FEA) software ABAQUS. It is indicated that this mode is correctcompared with the domestic scholars’ test results.Clear the characteristics ofhysteretic curves and envelop curves through the calculation of endplate connectionto CFST column with blind bolts under cyclic loading. The ultimate states,failuremodes, the co-work between the beam and the column, materials and the nonlinearvariation process were clarified.(3) The analytical models of endplate connection to CFST columns undercyclic loading were developed by finite element analysis (FEA) softwareABAQUS. Several main factors which is very important for hysteretic curves ofmoment-rotation relation were clarified, such as the strength of steel, the strengthof concrete, axial load level, slenderness ratio of column, beam-column stiffness，and etc.(4) Based on the test and theoretical analysis, some reasonable structuralmeasures were suggested, such as setting level axillary on beam flange, stiffeningribs on column wall and endplate, increasing the anchoring length of bolts,andetc.These structural measures can improve the moment bearing capacity and theinitial stiffness, ensure the safety of the connection.