Experimental Study On Seismic Performance Of Composite Frame Interior Joints Consisting Of Srrc Columns And S Beams

The steel reinforced recycled concrete(SRRC)column has a high bearing capacity and good seismic performance.At the same time,the steel(S)beam has good mechanical properties and convenient construction.Combined with the above characteristics,the composite frame structure consisting of SRRC columns and S beams was put forward in this paper.The new structure not only has good seismic performance,but also has the remarkable characteristics of green environmental protection,which accord with the strategies of national sustainable development.Therefore,the composite frame structure consisting of SRRC columns and S beams has a broad application prospects.In this paper,through experimental research and theoretical analysis,the seismic behaviors of composite frame interior joints consisting of SRRC columns and S beams were researched in detail.The main research contents and results are as follows:(1)According to the test requirements,the C40 recycled concrete materials were designed and prepared.On this basis,5 composite frame interior joints were designed and a study on cyclic loading test was conducted.The design parameters mainly include recycled coarse aggregate replacement ratio and axial compression ratio.(2)Through the low cyclic loading test,the failure processes and features of the specimens were observed and the hysteresis curves,skeleton curves and load-strain curve were also obtained.On that basis,the horizontal bearing capacity,ductility,lateral angles,strength attenuation,stiffness degradation,seismic capacity and strain were researched in detail,and the effects of testing parameters on seismic behavior of specimens were analyzed.(3)It is shown that the main failures of composite frame interior joints are typical shear damage,and the shear deformation in core zone of the joint are obvious.The hysteresis curve is spindle shaped,which shows good energy dissipation capacity;The recycled coarse aggregate replacement ratio has less effect on seismic performance of specimens.The energy dissipation capacity,ductility and shear capacity of the composite frame interior joints decrease with the increase of recycled coarse aggregate replacement ratio.The effect of axial compression ratio on seismic performance of the specimens is more obvious.Along with the increase of axial compression ratio,the horizontal bearing capacity of specimens improved continuously.However,the stiffness degradation and strength attenuation obviously increased,and the deformation ability degraded significantly after the peak load,which shows the energy dissipation capacity reduced as a whole.(4)On the basis of experimental research,considering the elastic section,the cracking section,the yield section and failure stage of four typical sections,the fitting method is adopted to establish four line skeleton curve model and hysteretic curves model,and the loading and unloading stiffness degradation law and hysteretic rules of the whole process were described.After verification,the results show that the proposed model is in good agreement with the experimental curves,which can well reflect the hysteretic behavior of specimens under low cyclic loading.Through the experimental study and theoretical analysis,it can be concluded that the composite frame interior joints consisting of SRRC columns and S beams has good bearing capacity and seismic performance,which can be applied to practical engineering through reasonable design.The results can be used as a reference for elastic-plastic analysis and seismic performance evaluation of the composite frame interior joints consisting of SRRC columns and S beams.