Study On Simplified Load Model And Dynamic Response Of Subway Station Structures Under Explosion

The subway station is airtight and crowded.Once a terrorist explosion occurs,it will not only cause a large number of casualties,but also cause the destruction of the structural components of the station,and even the progressive collapse of the structure.In this paper,study the overpressure load on the structure and the dynamics response and the destruction model of the station structure during the close explosion with LS-DYNA.The main research contents are as follows:(1)Through LS-DYNA finite element software,the range of the air area around the platform pillar during the explosion inside the metro station is determined,and the propagation process of explosion shock wave is simulated;the characteristics and distribution of the time history curve of the overpressure load on the platform column surface under 120 working conditions are analyzed;a simplified overpressure load model and a load space model suitable for the platform column are proposed,and the applicability of the simplified model is analyzed.(2)The multi-scale finite element model of subway station structure is established,and the failure modes of platform pillars under different explosive equivalent and explosive distance are analyzed by simplified model of overpressure load,and the development process of various failure modes are also analyzed.A formula for calculating the damage length and maximum horizontal displacement of platform column under close-range explosion is proposed,which can quickly predict the failure modes of platform column.(3)The dynamic response of subway station structure is analyzed by direct simulation method and demolition method.The results show that the vertical displacement of the top of the column obtained by demolition method is larger,the difference is about 60%.When a single platform column fails,the station structure will not collapse continuously.A simplified method for dynamic response analysis of station residual structure with residual coefficient of bearing capacity is proposed which can avoid the establishment of complex finite element model to rapidly analyze the dynamic response of station residual structure when platform column fails.