Experimental Investigation And Numerical Simulation On Dynamic Response Of Steel Tube Members Under Explosion Loading

In recent years,the worldwide explosion accidents occur frequently.Explosion refers to damage effect on building structures.It happens in a very short period of time,releases a large amount of energy and high temperature,and emits large amounts of gas caused by chemical reaction or voltage changes in the surrounding medium.It can heavily destruct the surroundings,so doing research on explosion has a very important significance and application value.The transmission tower material of steel tube structure is easy to be purchased and installed,the steel tube shape is good,and its windward coefficient is small,so it is widely used in the high-voltage transmission tower structure.In this paper,the dynamic response and the time history curve of steel tube members under blast loading is analyzed,and a numerical model of steel tubular members under blast loading is established,and the influence factors of displacement is analyzed through experimental research and numerical simulation.The main work and conclusions in this article are as follows:(1)Summed up the basic theory of explosion through the literature.Expounded the formation,action,reflection,flow and propagation of shock wave and the concepts of failure.Sorted out the parameter and formula of the wave state parameters,the proportional distance,the peak overpressure,the positive pressure time and the positive impulse.Briefly described the dynamic characteristics and application of emulsion explosives,and described the dynamic characteristics under high strain rate.(2)Determined the method of static explosion test base on explosion theory and similarity principle,and did 12 experiments on the steel tube members in the proportion of 1.512/m/kg1/3,1.007/m/kg1/3,0.504/m/kg1/3 and 0.120/m/kg1/3.Measured the overpressure time history curves in the free surface of the top,middle,the back surface of the middle and the free field with equal distance,summarized the data.And got a further understanding of the propagation law of explosive shock wave and the dynamic response characteristics of steel tube members.In the near field explosion,the blast impact load has a great impact on the local part of the steel tube component,which makes the middle part of the steel tube component show the failure form of the tear and local buckling.In the far field explosion,the impact load reaches in a longer time,the peak value is lower,and the action time is longer.In addition to the influence of the first wave front,the shock wave reflected by the ground also has an influence on the component.(3)Used the nonlinear finite element software ANSYS/LS-DYNA and selected the appropriate material model,the calculation parameters and the boundary conditions to establish the numerical model of the interaction between blast shock wave and steel tube.Compared the numerical simulation results with the experimental results to verify the rationality of the numerical model.The wave propagation law is verified,and the reasons for the error between the experimental results and numerical simulation results are analyzed.Based on the numerical simulation,the elastic deformation and recovery process in the static explosion test were observed.The failure modes of steel tube members are classified as bending failure,shear failure and shear failure.(4)The motion of the particle is a sine or cosine curve under the action of un-damped equivalent triangle impact load.The maximum displacement in the middle part of the structure under the impact load of the component is evaluated.The sensitivity of the steel tube components to the blast resistance is influenced by various factors: The length of the component > steel strength > wall thickness.So in order to improve the blast resistance of steel pipe,diameter should be reduced as far as possible.When the diameter is fixed,we can reduce the length or increase the strength of steel to improve its anti-explosion ability.