Seismic Damage Behavior Of Aeolian Sand Concrete-filled Round Steel Tube Column

River sand,as a kind of non-renewable construction resource,is facing the problem of lack of river sand resources at present.If it continues to be mined without limit,it will inevitably cause serious damage to the natural environment.Therefore,looking for its substitute material has become one of the key research points of sand for concrete.There are a large range of desert areas in China,so the reserves of aeolian sand are extremely rich.If it is applied to engineering practice,it will bring great ecological and economic benefits.In order to promote the application of aeolian sand resources in steel-concrete composite structures.In this paper,the aeolian sand of Kubuqi Desert in Tuoketuo County of Hohhot city is selected as raw material,the seismic performance of aeolian sand concrete-filled round steel tube columns was studied by low cycle repeated load test.1.Research on low cyclic load testConsidering the different aeolian sand replacement rate and structure form,Design and manufacture 4 specimens of aeolian sand concrete-filled round steel tube column with the aeolian sand replacement rate of 10%-40% and 4 specimens of Circular section aeolian sand concrete column with spiral reinforcement(as control group)with the aeolian sand replacement rate of 10%-40%.Through low cycle repeated load test,the failure characteristics,hysteresis curve,bearing capacity,ductility,stiffness degradation,energy dissipation and other seismic performance indicators of each specimen were compared and analyzed.The results show that the hysteretic curves of each specimen are basically prismatic,relatively full,and showing good ductility;In the case of the same replacement rate of aeolian sand the seismic performance of the specimens can be significantly improved by setting the Wrapped round steel tube.Through the comparison between the calculation results and the test results,it can be seen that the calculation formula of shear capacity of ordinary concrete-filled steel tubular column in the relevant codes and regulations of our country can be applied to the eolian sand concrete-filled round steel tube column,and the calculation result is safe.2.Research on damage performanceOn the basis of low cyclic load test,The damage evolution process of the aeolian sand concrete-filled round steel tube column specimen based on single deformation parameter,single energy dissipation parameter and double deformation and energy dissipation parameter was studied,and the two-parameter damage model of deformation and energy dissipation is further modified,so as to better reflect the evolution law of seismic damage of the eolian sand concrete-filled round steel tube column,and provide the basis for their seismic damage analysis,according to the measured data,the model of restoring force is established for the eolian sand concrete-filled round steel tube column.3.Research on resilience modelBased on the experimental fitting method,a three fold skeleton curve model of the eolian sand concrete-filled round steel tube column is established,the model is in good agreement with the skeleton curve measured in the experiment.Through the regression analysis of the curve characteristics and test data of the specimen,the stiffness degradation law is obtained,and the restoring force model of the specimen is established.The calculation results show that the model is in good agreement with the test results,which can provide a basis for the elastic-plastic analysis of the eolian sand concrete-filled round steel tube column under earthquake action.4.Finite element analysisUsing ABAQUS finite element simulation software,the finite element model of the eolian sand concrete-filled round steel tube column is established and the model was tested by simulating low cyclic load.The calculated results are in good agreement with the measured data.On this basis,by changing the test variable axial compression ratio,thickness of specimen steel tube wall,strength grade of aeolian sand concrete and other related parameters,the influences of different parameters on the seismic performance of the eolian sand concrete-filled round steel tube column were calculated and analyzed.