Safety Assessment And Countermeasures Of Multi Layer Frame Under The Fire And Low Speed Impact

In recent decades,unexpected accidents are more and more with the wide application of reinforced concrete.It is giving huge losses to the people's production and life,and even threatened the people's lives and property.Through the review of the literature I found the reinforced concrete structure was suffered by fire or collision accidents accounted for half of the structure from above,and studied separately by fire and the impact on the structure has been very extensive,but the study on the two conditions together has not seen.Therefore,to study the failure mechanism of frame structures under fire and low velocity impact,and to put forward effective countermeasures has great significance.First looking at the concrete and steel reinforced by fire and the impact of the literature,by comparing the research results at home and abroad,the constitutive equations,parameters and formulas for calculating fire and impact are selected.Second establishing three stories and three spans reinforced concrete frame model by ABAQUS software,The first step is to simulate fire in the different parts of the bottom and simulate the influence of low velocity impact load on the structure,It is found that the RC frame structure under low velocity impact will have local damage,and will not have impact on the overall frame structure.Then the reinforced concrete frame structure under fire is simulated at low speed and compared with the model of low velocity impact without fire,the results show that the damage to the underlying columns after fire is higher than that of the latter,and increased structural risk.The influence of different parameters on the structure was studied by changing the parameters of the model.It is found that the impact velocity has larger influence on structure than the impact mass,the fire condition and the impact site.It is found that under different fire conditions,the failure rate of concrete in the bottom side column is 20m/s~23m/s.Finally on the base of the frame structure,the protective structure is set up and use the ABAQUS finite element method to simulate.The results show that the method of carbon fiber reinforced plate and the external steel plate method are very effective to reinforce the columns after fire.