Research On Dynamic Response Of Equilateral-Angle Steel Member Under Blast Loading

In recent years, there are many accidents caused by explosions all over the world. The explosion shock wave is characterized three kinds of effects. That is high peak, short duration and fast attenuation. Therefore, its damage to human and architecture structure is extremely serious. Equilateral-angle steel as the main component in the transmission tower structure, due to the features of reasonable stress, high bearing capacity, easy to install, easy to transport advantages, has been widely applied.Therefore, study on how the equilateral-angle steel member would respond to dynamic changes under explosion loading has a very important theoretical significance and practical value in engineering. This paper uses the method of theoretical analysis, experimental research and numerical simulation research to facilitate the whole process; the interaction between explosive blast and equilateral-angle steel member, dynamic response and influence factors and failure mode are thoroughly discussed by using methods mentioned above. In this study, major research work and outcomes are listed below:(1) In accordance with explosive blast basic theory, there 9 kinds of conditions have been determined in the static explosive experiment of equilateral-angle steel member. The experiment measured the overpressure distribution of three places and the displacement lengths in the middle of equilateral-angle steel member. These data provides grounds for predicting the propagation mode of explosive blast and the stress characteristics of equilateral-angle steel member under blast load. When component meet the blast, which including the bottom top and the middle component, by the test to the explosion shock overpressure and the time history curve of deformation. This paper can achieve the further understanding of the explosion shock wave propagation way and equilateral-angle steel member in the mechanical characteristics under blast load.(2) This paper establishes the numerical simulation for the interaction between explosive blast and equilateral-angle steel member. Based on ALE fluid-solid coupling algorithm, this paper forms the numerical model for the interaction between explosive blast and equilateral-angle steel member through choosing suitable material model and model parameters. By contrast result between the explosive experiment and the numerical simulation, it proves the numerical simulation is reliable. Based on the result of the explosive experiment and the numerical simulation, this paper get the theoretical model about the relationship between the peak overpressure and scaling distance for the rock emulsion explosives explosions in air.(3) This paper establishes the numerical simulation for the dynamic response of equilateral-angle steel member under the blast load. Through a large number of numerical simulations, this paper studied the influence that scaling distance, width-thickness ratio and yield strength of steel would do to the dynamic response of equilateral-angle steel member.(4) The result of experiment shows that, as the width-thickness ratio increased, the peak overpressure of each measuring points and the residual deformation in the middle of equilateral-angle steel member increased as well. The peak overpressure gradually decreased on both ends of member height. In the contact-field, the failure mode of the equilateral-angle steel member is partial flexural mode due to the blast load.(5) The result of parameter analysis shows that, as the scaling distance decreased, the maximum horizontal displacement and the residual deformation in the middle of the equilateral-angle steel member and the residual displacement grows significantly. When the scale distance is over 0.6 m/kg1/3, it's influence on horizontal displacement can be ruled out. When the width-thickness ratio is over 10, the extent of destruction of the equilateral-angle steel increased remarkably. Improving the yield strength of steel would optimize anti-explosion performance of the equilateral-angle steel member.