| The steel tube can effectively restrain the internal concrete,solve the brittleness and strength problems of recycled concrete,and provide a new idea for the application of recycled concrete.Recycled concrete-filled steel tubular structure in the service process in addition to the load,but also affected by corrosion factors,in order to study the mechanical properties of circular recycled concrete-filled steel tubular column in chloride environment,this paper through experimental research,theoretical analysis and finite element simulation of circular recycled concrete-filled steel tubular column in chloride environment under axial compression.The main contents are as follows:(1)The axial compression tests of recycled concrete filled steel tubular columns with different test parameters were designed,including two circular steel tubular columns,30 circular recycled concrete filled steel tubular columns with different concrete strength grades(C30,C45,C60),different wall thicknesses(3mm,4mm)and different chloride corrosion degrees(0%,5%,10%,15%,20%),The effects of concrete strength,steel tube wall thickness and corrosion degree on the bearing capacity,displacement,stiffness,ductility,strain and residual deformation were studied.(2)In this paper,the strength improvement coefficient of recycled concrete-filled steel tubular column under chloride environment is introduced,the calculation method of axial compression bearing capacity is derived,the influence of different pressure measurement coefficient on the results is compared and analyzed,and the reasonable value is obtained by comparing with the experimental results;the ultimate bearing capacity of each specimen is calculated and analyzed by referring to the current domestic and foreign codes,and the anastomosis process of the two is compared and analyzed Degree.(3)The software ABAQUS was used to establish the finite element numerical analysis model,and the damage deformation and load displacement curves of each specimen were obtained.Compared with the test results,the accuracy of the finite element analysis model was verified.The main conclusions are as follows(1)The failure modes of the specimens are basically the same,and the specimens bulge continuously in many places,resulting in axial compression or shear slip failure.With the increase of corrosion degree,when the load reaches the peak value,the failure rate of specimens is accelerated,and there are many continuous bulges on the surface of recycled concrete filled steel tubular columns with high corrosion degree.(2)According to the different applied loads,the load longitudinal displacement curve of each specimen can be divided into straight-line rising elastic section,curve rising elastic-plastic section and failure section.The results show that the increase of steel tube wall thickness has limited influence on the axial compression stiffness of the specimen,but it has obvious improvement on its ultimate bearing capacity and ductility;the higher the strength of recycled concrete,the greater the ultimate bearing capacity,stiffness and ductility of the specimen;the bearing capacity and ductility of the specimen decrease under chloride corrosion.(3)Based on the limit equilibrium theory,the calculated results increase with the increase of pressure coefficient.When the value is between 3 and 4,the calculated results are in good agreement with the experimental results.The ratio of the calculated value to the test value is between 0.678 and 1.278.The calculated value of cecs 28 and Eurocode is more consistent with the test value.(4)The stress nephogram and skeleton curve obtained from the finite element analysis are in good agreement with the experimental results,which indicates that the analytical model can effectively simulate the bearing and deformation performance of recycled concrete filled steel tubular columns in chloride environment. |
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