Experimental Investigation On The Residual Strength Of Concrete-Filled Steel Tube Column After Subjected To Lateral Impact

From the point of view of shape,concrete-filled steel tubular column is made up of concrete-filled circular steel tubular column,concrete-filled square steel tubular column,round-end concrete-filled steel tubular column and concrete-filled polygonal steel tubular column.The concrete-filled circular steel tubular columns and concrete-filled square steel tubular columns are most commonly used.The concrete filled steel tube has the advantages of good ductility,high bearing capacity,good seismic performance,which is good for the fire resistance and fireproofing of the steel pipe,the improvement of corrosion resistance of steel structure and the convenience of construction,and the shortening of construction period.Therefore,as the member of concrete-filled steel tube,the concrete-filled steel tubular column is widely used in the engineering practice.So it is very necessary to make a study of its mechanics.In this paper,the mechanical properties and residual bearing capacity of concrete-filled circular steel tubular columns and concrete-filled square steel tubular columns after lateral impact load are studied respectively.In this paper,48 concrete-filled circular steel tubular short columns are made with variables of impact energy,impact position and strength of core concrete,of which there are three without impact load.After the impact test,it is found that the concrete-filled circular steel tube subjected to the impact gets the greater deformation and the more serious damage when the core concrete strength is lower,the impact position is closer to the end of the specimen and the impact energy is greater.Through the axial compression test of concrete-filled circular steel tubular short columns after the lateral load,the paper focuses on the mechanical performance and damage mode during the axial compression test.It is discovered that all variables make influence in some degrees,which initial stiffness,ductility and the ratio of the residual strength comparing to the original strength falling more with the increase of impact energy,the strength of core concrete and the decrease of distance to the end of the impact energy.Besides,the paper carries out the research on the strain of concrete-filled circular steel tubular column during the experiment and it is found that the stress at the impact point grows faster than the opposite and the side in elastic and plastic phases.At last,the analysis,which is for the impact energy,impact location and strength of core concrete,on the influence to the ratio of the residual strength comparing to the original strength is gave out,based on the compressive experiments of 45 concrete-filled circular steel tube column after subjected to lateral impact and 3 concrete-filled circular steel tube column without subjected to lateral impact,as while as the calculation formula of the ratio of the residual strength to the original strength is worked out.To concrete-filled square steel tubular column,48 concrete-filled square steel tubular short columns are made with variables of impact energy,impact position and strength of core concrete,of which there are three without impact load.After the impact test,it is found that the concrete-filled square steel tube subjected to the impact gets the greater deformation and the more serious damage when the core concrete strength is lower,the impact position is closer to the end of the specimen and the impact energy is greater.By the axial compression test of concrete-filled square steel tubular short columns after the lateral load,the paper focuses on the mechanical performance and damage mode during the axial compression test.Then it is discovered that all variables make influence though in different degrees,which initial stiffness,ductility and the ratio of the residual strength to the original strength fall more with the increase of the strength of core concrete,impact energy,and the decrease of distance to the end of the impact energy.Besides,the paper carries out the research on the strain of concrete-filled circular steel tubular column during the experiment and it is found that the vertical and horizontal train are basically the same in the elastic and plastic phase while the impact point is greater than the others,and the corner portion is larger than the plan for high-grade core concrete specimens,but the corner portion of side plan is largest for low-grade core concrete specimens.At last,the analysis,which is for the impact energy,impact location and strength of core concrete,on the influence to the ratio of the residual strength to the original strength is gave out,based on the compressive experiments of 45 concrete-filled square steel tube column after subjected to lateral impact and 3 concrete-filled square steel tube column without subjected to lateral impact,as while as the calculation formula of the ratio of the residual strength to the original strength is worked out.