Study On Dynamic Behavior Of Base-isolated Structures Under Blast Impact

With the continuous development and utilization of seismic isolation technology,it has been widely used by more and more civil buildings due to its advantages such as good seismic performance and low cost.In recent years,explosions caused by gas leaks and improper accumulation of flammable and explosive materials have occurred frequently in civil buildings.The impact of explosion shocks on buildings has caused serious damage to people's lives and safety.At present,the research on the dynamic response of indoor explosions of isolated structures and the continuous collapse of structures is very scarce.Therefore,this article will use LS-DYNA finite element software to simulate the impact of explosions caused by gas leakage on isolated structures,and replace the gas with equivalent explosive The explosion impact damage caused by the leakage is analyzed by analyzing the explosion response characteristics of the isolated structure by changing the position of the explosive,and the damage process of the isolated structure is studied and summarized.The main research contents of this article are:(1)This article reviews the destroy mechanism of structures under blast loads at home and abroad,and proposes reasonable research methods for specific problems in this article.Determine the calculation parameters: the selection of the seismic isolation,the material of the explosive material,the selection of the constitutive model,the selection and treatment of the boundary conditions,the contact method,etc.The LS-DYNA analysis software was used to simulate the formation,diffusion and propagation of the explosion in the soil cavity using a fluid-solid coupling method,and compared with experimental data in the literature to verify the rationality and effectiveness of the model.(2)The impact of different explosive positions on the isolation and deformation of the isolation layer is simulated and analyzed.The effect of gravity load on the overall structure is not considered during the entire simulation analysis.The explosives were placed at the same height near the center pillar,the corner pillar,and the inner center pillar.The effects of the damage of different key pillars on the overall isolation structure were analyzed.The simulation analysis found that the damage near the long side pillars greatly affects the overall structure.(3)Study the overall structure destroy process when the simulated explosive is near a fixed key column and the height of the explosive is 0m,1.65 m,2.75 m.The simulation analysis found that the first layer of the members of each layer has the most damage,and the explosive height is0 m position,the overall deformation of the structure is relatively large.(4)According to the collapse criterion in GSA2003,a direct simulation method with short simulation calculation time and intuitive and accurate calculation results is selected from two continuous collapse analysis methods: alternative force transmission path and direct simulation forcontinuous collapse analysis.A gravity system was used to apply the restart function to establish a coupled system model of the foundation soil,explosives,air,and the isolated structure,and the collapse process and collapse method of the isolated structure were studied in the vicinity of different key columns.