Research On Shear Behavior Of Through-Diaphragm Connection Between CFST Column And H-shaped Steel Beam

Through-diaphragm connection between concrete-filled steel tubular column and steel beam has been recommended in technical specification for structures with concrete-filled rectangular steel tube members(CECS159:2004),and increasingly used in structural engineering.The research on shear behavior and seismic performance of panel zone is still limited since the lack of experimental results.The calculation methods of shear resistance of panel zone still need verification.Previous experiment results were reviewed at first.Local buckling in tube web of panel zone was found in the connections with shear failure modes.However,the shear buckling behavior of panel zone was not considered in the existing calculation equations for shear resistance.This paper experimentally studied the seismic behavior of through-diaphragm connections in shear failure mode of panel zone.Three specimens were designed for shear failure mode and tested under cyclic loading.The failure characteristics,loaddisplacement relationships,strain data was collected during the test.The seismic performance of the connections including the ductility,resistance,energy dissipation capacity and strength degradation was studied.With a slitting test of the core concrete,the diagonal strut in concrete was validated.The force transferring mechanism and failure characteristic was studied by finite elements analysis.The load-displacement relationships agreed well with the test results,and the failure mode was similar with the test specimens.Parametric studies were conducted to study the influence factors on shear resistance of panel zone.The results indicated that thickness of tube web in panel zone is the main factors influenced the shear resistance of panel zone,while the tube flange of panel zone make little effect on the resistance.The existing calculation equations for shear resistance of connections were reviewed.Focused on the failure modes of connections in this paper,a tension field model of tube web in panel zone was built.And based on this model,a calculation method for post-buckling shear resistance of pane zone was developed.The accuracy of this method was validated by the reported test results.Using regression analysis,a restoring force model of through-diaphragm connection was established.This model included the skeleton curves and hysteretic curves.The calculated skeleton curves agree well with the experimental ones and the calculated hysteretic curves have a good agreement with the experimental ones on their trends.The validations of the restoring force model against the test results confirmed the accuracy of the model in predicting the load-displacement relationships and the seismic behavior of the connections.This model can be used for the seismic response analysis on through diaphragm connections.