Cyclic Behavior Of Composite Joints Between Circular Hollow Steel Tube-reinforced Concrete Columns And H-shaped Steel Beams

Hollow concrete filled steel tube composite column is derived from the concrete filled steel tube composite column,it is a kind of structure very broad application prospect,The mechanical performance of the components is gradually perfect in recent years,However,the researches on these kinds of composite joints are still relatively less,for the potential application prospect of composite joints between circular hollow steel tube-reinforced concrete columns and h-shaped steel beams in real project.In this article,for studying its hysteretic behavior,several nonlinear finite element analysis models are set up which is used for the whole loading process of hollow steel tube-reinforced concrete column to steel beam joints under constant axial load on the top of column and cyclic load at the beam ends.Through the detailed analysis of finite element simulation result,3 failure modes of this kind of joint are divided,the whole process of joint stress in different failure modes is explained particularly,on this basis,detailed parameter analysis is done and the influence of different parameters to ductility,rigidity degradation,strength degradation,energy dissipation capacity and failure modes of joint is summarized.Finally the influence factors of joint hysteresis behavior are summarized systematively;the specific works are as below:First of all,on the basis of the parameters and loading system of the previous experimental study,the joint model is set up with the finite element simulation analysis software of ABAQUS and the material stress-strain relations and finite element modeling method in this article,after calculation and analysis,it is concluded that results of P-?hysteresis curve,skeleton curve and joint failure mode is very similar with previous experiment of the specimens,the accuracy of material stress-strain relations and finite element modeling method in this paper has been verified.Then,the finite element model of the joint in this paper has been set up and the calculation and analysis are carried out.The P-? hysteresis curve,skeleton curve and failure mode of the joint specimens under various parameters are obtained respectively.The failure mode of this kind of joint is roughly divided into three kinds,which is bending failure at end of column,bending failure at end of beam and mix failure,the whole stress process of three kinds of failure mode has been analyzed particularly,and the result shows that the typical P-?hysteresis curve is generally can be divided into 9 stages which is elastic stage,elastic-plastic stage,unloading stage,reverse elastic stage,elasto-plastic stage,unloading stage and reverse again by elastic stage,elasto-plastic stage and destroy stage.Finally,by comparing the hysteresis curves,skeleton curves,failure mode,strength and rigidity degradation,ductility and energy dissipation capacity of different parameters,the influence law to the joint of different parameters is concluded.The final result shows that it is ratio of beam-column bending capacity that decides the joint failure mode.