Nonlinear hysteretic model of prefabricated pier-cap beam joint with CFST socket connection

Concrete-filled steel tube possesses excellent mechanical properties and has been gaining increasing attention for its application in prefabricated pier-cap beam joints with socket connections. To comprehensively investigate the nonlinear force-displacement relationship of the prefabricated pier-cap beam joint with concrete-filled steel tube socket connection under cyclic loading, this paper first developed a mechanical analysis model for the joint. The deformation equation of the socket connection segment was derived based on Timoshenko beam theory, resulting in the establishment of the skeleton curve model for the joint. Additionally, the finite element model of the joint was developed to analyze the parameters and fit the unloading stiffness equation of the joint. The nonlinear hysteresis model of the joint was ultimately established by incorporating the hysteresis rule accounting for the pinching effect. The model accurately represented the joint's force-displacement relationship under cyclic loading, thereby providing theoretical support for the application of the joints in medium and high seismic regions.