Experimental Study On Seismic Performance Of Rubber Concrete Filled Circular Steel Tube Columns With Polypropylene Fiber

In this paper,experimental research and finite element simulation methods are used to explore the seismic performance of rubber concrete filled circular steel tube columns with polypropylene fiber externally.The main contents and findings of the research are outlined below:(1)Design and fabricate 10 circular concrete-filled steel tube(CFST)columns for low-cycle reciprocating loading test to simulate earthquake damage.The effects of different rubber powder content,slenderness ratio,axial compression ratio and steel content on the damage change of the specimen column were discussed.The hysteretic curve,skeleton curve,ductility performance,energy dissipation performance,and stiffness degradation data of the specimen were obtained.At the same time,the digital image correlation(DIC)and Acoustic emission(AE)instruments were used to measure the full field of the rubber concrete filled circular steel tube columns with polypropylene fiber externally the development of the drum warp deformation and the cracking condition of the concrete are monitored.The failure of rubber concrete filled circular steel tube columns with polypropylene fiber is similar to that of ordinary CFST column,which forms buckling at the root of the column and then is cracked.The incorporation of rubber powder will reduce the bearing capacity of the specimen,but improve the energy dissipation capacity and ductility of the specimen.Excessive axial compression ratio will make the rubber concrete filled circular steel tube columns with polypropylene fiber fail in advance,and the slenderness ratio has a great influence on the hysteretic process of the specimen.(2)Under low-cycle reciprocating loading,the failure of the rubber concrete filled circular steel tube columns with polypropylene fiber is buckling failure.The energy dissipation capacity of the rubber concrete filled circular steel tube columns with polypropylene fiber is significantly higher than that of the ordinary steel tube concrete column,and it has good seismic performance and ductility,but the increase in rubber powder will reduce the load-bearing capacity of the specimen.Using DIC technology,it is found that the specimen with 10% rubber powder content has a larger range of bulging than the specimen with 5% rubber powder content,and the deformation occurs earlier.Through AE technology,it is found that the specimen column is in the stage of failure and destruction,the internal concrete columns are mainly damaged by shear cracks.(3)On the basis of the experimental research,the finite element analysis of the rubber concrete filled circular steel tube columns with polypropylene fiber externally mixed with ABAQUS software was carried out.As for the seismic performance under load,the skeleton curve obtained by software simulation are in good agreement with the test results,and the cloud image is also consistent with the actual damage phenomenon of the test.The model has been verified very well,and this study has laid a good foundation for the application of rubber concrete filled circular steel tube columns with polypropylene fiber.