Study On Seismic Performance Of Frame Side Joint Of Recycled Aggragate Concrete Filled Square Steel Tube Column Versus Steel Reinforced Recycled Aggregate Concrete Beam

Recycled aggregate concrete filled steel tube(RACFST)structure not only has advantages of good mechanical properties and seismic performance,but also makes the most of construction waste,so it is a kind of structure with broad prospects.In order to promote RACFST structure further based on research results of our research team,this paper uses the steel reinforced recycled aggregate concrete(SRRAC)structure as the form of beam to explore seismic performance of the RACFST joint with SRRAC beam,moreover,the kind of joint is with outer reinforcing rings which transfer load simply and directly.This paper designs 8 specimens of the frame side joint with changing parameters of recycled aggregate replacement rate,axial compression ratio and beam-column's linear stiffness ratio to test seismic performance under the cyclic reversed loading.Purposes of the experiment include:recording the failure mode of specimens,acquiring a series of seismic performance index and analyzing how every changing parameter affects seismic performance of specimens.Based on the experimental data,this paper presents the restoring force model of the joint.Moreover,after doing the finite element analysis by using software ABAQUS to prove the established model of the joint is accurate,the paper extendedly analyzes seismic performance of the joint with more parameters such as axial compression ratio,structural measures of outer reinforcing rings and forms of beam.The studying results indicate that shapes of hysteretic curves are all plump.The ductility coefficients of all specimens are between 3.05?3.80,so that the kind of joint has good ductility.Also,the displacement angle of all specimens is between 1/43?1/25,and it is accordance with the requirement of the regulation.The ductility of specimens without recycled aggregate is better than those with recycled aggregate,however,the recycled aggregate replacement rate has little influence on the bearing capacity,energy dissipation ability,stiffness degradation of later period and accumulated damage.With the increase of axial compression ratio,ductility becomes worse,energy dissipation ability of later period,stiffness degradation and accumulated damage increase.With the increase of beam-column's linear stiffness ratio,the ductility,energy dissipation and stiffness degradation decrease,and the bearing capacity increases.After analyzing hysteresis curves' rules and skeleton curves of all specimens,the paper presents the restoring force model of the joint.As the result,the calculation restoring force curves are accord with the experimental hysteresis curves well.The results can provide reference for the analysis of the elastic-plastic dynamics of the joint.Finally,the paper verifies seismic performance of all specimens by using finite element analysis software ABAQUS.The results calculated by ABAQUS have good agreement to the test results,proving that the established model of the joint is accurate.On the foundation,results of the extended analysis are as follows:with the increase of the axial compression ratio,the bearing capacity and ductility of specimens decrease,so that we must notice the actual axial compression ratio in engineering projects.Increasing the width or thickness of outer reinforcing rings with limits is good for seismic performance of the joint.Moreover,the bearing capacity and ductility of the joint with SRRAC beam is better than the one with RAC beam.