Study On Continuous Collapse Resistance Of Reinforced Concrete Frame Structure In Gas Explosion

The continuous collapse of building structures caused by explosion load has attracted much attention in the engineering field.Scholars at home and abroad have done a lot of research on this problem,but they mainly focus on explosive explosion,automobile explosion,terrorist attack and so on,and pay less attention to gas explosion.In cities,gas is a necessity for residents’ life.Improper use may lead to explosion risk,which may cause component damage or continuous collapse of structures.Therefore,taking a civil reinforced concrete frame structure residence as an example,the performance damage of frame columns,dynamic response and continuous collapse resistance of the structure during gas explosion are studied by using the direct dynamic method.Firstly,referring to the research of domestic and foreign scholars on gas explosion,the over-pressure peak value and action time of gas explosion shock wave are determined,and the over-pressure time history curve of shock wave is simplified.Then,combined with the model example,the stages of the shock wave acting on the frame structure are analyzed.The shock wave action is simplified as a line load applied to the frame column and frame beam,and the gas explosion load which can be used to analyze the continuous collapse problem by the direct dynamic method is obtained.According to the material dynamic constitutive relationship under gas explosion,the reinforced concrete column analysis model is established in ABAQUS,and six examples are set to analyze the influence of different concrete ultimate compressive strain on the calculation results.Combined with the actual situation of gas explosion accident,the reinforced concrete failure criterion suitable for this model is obtained.The dynamic analysis of frame columns is carried out by applying three peak explosion loads,and the decline degree of bearing capacity of frame columns under three peak values is obtained.The damage of frame columns is evaluated based on the bearing capacity damage criterion,and the damage index and corresponding fitting formula of frame columns under different peak values are obtained,which provides a reference for the damage evaluation of frame columns under gas explosion.The overall model of the frame structure is established in the finite element software SAP2000.The nonlinear dynamic time history analysis method is used for calculation.Twelve working conditions of gas explosion loads with different peaks and different action positions are set to analyze the dynamic response and continuous collapse of the frame structure.The results show that the continuous collapse resistance of frame structure under the action of peak gas explosion is low,the acceleration of frame joints will increase greatly when continuous collapse occurs,and the continuous collapse resistance of frame structure is higher when gas explosion occurs in the middle floor and middle span of frame structure.Finally,according to the calculation results,some suggestions to improve the continuous collapse resistance of the structure are put forward.