Experimental Study And Mechanical Behavior Analysis Of Steel Reinforced Concrete Column With T-shaped Steel Cross-section Under Lateral Impact

Steel reinforced concrete(SRC)structures have the advantages of corrosion resistance,fire prevention and convenient construction,and show good seismic performance under earthquake.SRC columns are adopted as the main structural lateral resistance members in a large number of high-rise and super-high-rise buildings.However,SRC columns arranged outside the building plane are vulnerable to impact loads caused by vehicle impact,terrorist attacks and various safety incidents,which lead to serious disaster effects of the structure.Therefore,the performance research and design countermeasures of steel reinforced concrete columns under impact loads have become an urgent problem to be solved in the application of such structures.In this paper,steel reinforced concrete columns with T-shaped steel cross-section are taken as research objects,and the performance of steel reinforced concrete members subjected to lateral impact loads is studied by means of experimental and numerical simulation methods.The main research contents and conclusions are as follows:(1)Seven steel reinforced concrete specimens with T-shaped steel cross-section were designed and manufactured in accordance with the existing codes of China.Considering the impact height,stirrup spacing and axial compression ratio of drop hammer,the lateral impact simulation test was completed by gravity drop hammer testing machine system,and the failure modes of the specimens were analyzed.The performance indexes such as impact force time history curve,maximum displacement in span and residual deformation were measured.The impact resistance of steel reinforced concrete columns with T-shaped steel cross-section was investigated.The results show that under lateral impact load,steel reinforced concrete columns with T-shaped steel cross-section have good overall impact resistance,and the main failure mode is bending-shear failure;with the increase of impact height,stirrup spacing and axial compression ratio,the damage degree,the mid-span displacement and residual deformation of members increase;increasing stirrup spacing weakens the restraint of reinforced skeleton on concrete,leading to inclined cracks.Increasing the axial compression ratio inhibits the development of bending cracks to a certain extent,but the inclined cracks are more serious and the inclination angle of inclined cracks is smaller.(2)The finite element analysis software ABAQUS is used to establish the model of steel reinforced concrete column with T-shaped steel cross-section.Considering the coupling of axial force and impact force,the stress distribution law of steel reinforced concrete members is analyzed.The comparison between numerical calculation and test results shows that the numerical model can well simulate the stress process of members under lateral impact load.The results of parametric analysis show that the dynamic response of members increases with the increase of impact height,stirrup spacing and axial compression ratio.With the increase of impact height,the peak value of impact force,the mid-span displacement and residual deformation of components increase;with the increase of stirrup spacing,the peak value of impact force changes little,but the mid-span displacement and residual deformation of components increase significantly;with the increase of axial compression ratio,the peak value of impact force and the mid-span displacement and residual deformation of components increase.The analysis of the stress distribution of the steel frame in the member shows that the web is the first line of defense and the flange is the second line of defense to resist the lateral impact load.