Analysis On Dynamic Responses And Progressive Collapse Of Steel Frame Structure Subject To Internal Gas Explosion

With the rapid development of economics, natural gas has been widely used all over the world. Gas explosions happen frequently lead to huge damage of structures. Gas explosion not only cause the casualties and property loss directly nearby the explosive source, but also lead to local damage even as progressive collapse of the building. As steel structures have been widely used in industrial and civil construction, study on dynamic responses and collapse mechanisms of steel structures under internal gas explosion have been a hot research topic in civil engineering and related fields.The purpose of this paper is to research on the propagation law of internal gas explosion shock wave and the dynamic responses and damage of steel frame structure subject to the internal gas explosion, to provide some suggestions about blast-resistant and blast-resistant design methods of steel frame structure. Firstly, by way of changing the parameters such as the volume, density of a gas mixture and pressure venting window setting effect on internal gas explosion, the simulation of internal gas explosion wave propagation in a three-story steel frame structure and the pressure of shock wave that acting on floors and walls in explosion room and nearby regions were investigated. Based on fluid-structure coupling method, using ANSYS/LS-DYNA dynamic analysis software, the finite element model was presented for the simulation of internal gas explosion. Secondly, when the conversion over pressure of floors and walls action on beams and columns of steel frame, impact responses and failure modes of steel frame under different pressure peak were investigated, duration and the role position blast loading are conducted. At last, the collapse process of structure with the larger blast loads action on different form structure bottom corner rooms are simulated.Through theoretical analysis and numerical simulation, the main results are included as follows:(1) The fluid-structure coupling method can well simulate shock wave propagation law of internal gas explosion and the action on the structural.(2) Locality is the characteristic of explosion pressure in sealed space, and the pressure pass weakly when it propagates in solid such as floors and walls in structures. When gas explosion occur in enclosed space, some times setting up reasonable pressure venting window can reduce the impact of structure damage under blast loading.(3) When the explosion load is smaller, the steel frame beams and columns directly subject to blast loading tend to cause large plastic deformation and the members away from explosion source cause smaller deformation. Explosion actions have the characteristics of locality and weak transitivity.(4) The dynamic responses of steel frame structure increased with the increasing of the peak pressure, even caused progressive collapse of steel frame structure. The deformation of frame structure under blast loading that act on middle position of frame structure is greater than the loads act on side or corner position of frame structure.