Study On Dynamic Response And Residual Bearing Capacity Of H-shaped Steel Column Under Weak Axis Direction Impact Load

Steel structure as one of the main building structure type,because of its high strength,light weight,plastic toughness and simple construction,is more and more used in large factories,super high-rise buildings,and its during service,inevitably encounter some accidents,small to vehicle collision,gravel splash,aircraft impact,explosion impact,the impact of these accidents will bring irreversible damage to steel structure building.The existing research work on the impact response of H-beam mostly sets the impact direction as the impact in the strong axis direction,and lacks the research considering the impact from the weak axis direction.However,the actual experience shows that under the same impact load,the impact in the weak axis direction will lead to more serious deformation than that in the strong axis direction.At the same time,in the relevant damage assessment or residual bearing capacity assessment,the common method is to give the empirical formula in a certain value range by fitting,but the results obtained by this method have great limitations,especially when the length and size of members change,or the load exceeds the range,it is no longer applicable,and can not meet the needs of damage assessment in practical engineering.In order to make up for the deficiency of this work,this paper studies the dynamic response and damage characteristics of H-shaped steel column under weak axial impact load.The main work and conclusions are as follows:(1)Study on weak shaft direction of H-type steel columnA total of 26 pieces of H-type steel columns were tested by the independently designed drop-hammer test device.The test results show that the impact position,axial pressure ratio and steel strength mainly affect the impact force platform value;the development factors affecting plastic displacement can be classified as impact strength,the impact area of H steel members can be divided into overlapping areas and non-overlapping areas,and the impact of the weak axis direction shows different damage modes and energy dissipation ability.(2)Finite element analysis of H-type steel columnA numerical model was established based on the large finite element software ABAQUS to further analyze the impact response process.Numerical simulation results show that the residual stress distribution after the impact is mainly located in the impact area and the column end,and the influence of inertial force on the component is mainly concentrated in the early stage of the whole movement process.Later,the results of the numerical simulation through the gray analysis,the impact energy is the main factor affecting the displacement response of the H steel components,and according to the final damage degree of the component,the weak axis direction damage mode is divided into three categories,by fitting three types of damage mode critical area equation,can judge the damage mode,achieve the purpose of rapid evaluation of damage components.(3)Study on the residual bearing capacity of the damaged H-shaped steel columnBased on the large finite element software ABAQUS,the axial compression simulation of impact-damaged specimens is conducted,and the relationship between impact energy,plastic displacement,impact direction and residual bearing capacity is analyzed.The analysis results show that a very small degree of plastic displacement will lead to a large reduction in the carrying capacity of H-shaped steel components.On this basis,the damage under the impact is assumed to be the initial defect.From the relationship between the remaining carrying capacity coefficient R and the overall stability coefficient under the initial defect,the calculation method of the residual carrying capacity coefficient R is proposed,and the accuracy of the formula is verified.