Hysteretic Experiments And Theory Of Endplate Composite Joints To Concrete Filled Thin-walled Steel Tubular Columns

The present studies on the mechanical behavior and design of the H-type steelcomposite frame joints are rich in quantity, but for the seismic behavior and designof cold-formed steel concrete composite frame joints.Our studio had carried outstudies on static behavior and seismic behavior of cold-formed thin-walledconcrete filled steel tubes-steel beam end plate joints. On this basis, thecombined effect of the concrete floor was taken into account in this paper.Experimental and theoretical study of the hysteretic behavior of the end platethin-walled steel concrete composite frame joints has important theoretical andengineering significance.(1) Low cyclic loading experiments was carried out on two full scale endplate cold-formed steel concrete composite frame joints.A detailed analysis aboutthe hysteresis curves and skeleton curve of horizontal load-horizontaldisplacement and connecting moment-rotation including strength capacitiesdegradation，stiffness degradation，ductility, energy dissipation capacity wasobtained，as well as stress distribution and development of the various componentsof the joint.(2) Using the ABAQUS finite element program, considering the geometricnonlinearity, material nonlinearity and contact problems, finite element models ofthe combination of joints were made to carry out non-linear loading processanalysis of the composite joints. The correctness of the theoretical model isverified by experiments.(3) Standard joints model was established on the basis of relevant impactparameters to analyze the relationship of horizontal load(P)-horizontaldisplacement (△)， and relationship of connection moment (M)–rotation (θr).Some important parameters of bending moment capacity and initial stiffness wasdetermined, laying out a theoretical foundation for the joint design method.