Numerical Simulation On Underground Concrete Frame Structures Subjected To Fire Loading

In recent years,the development and utilization of underground spacehas brought great convenience to people's production and life.As the main use form,traffic tunnel and underground integrated corridor are rapidly developing.However,fire that is main disaster is frequent when the traffic tunnel and underground integrated corridor bring the convenience to people's production and life.Due to the closure of the environment and the difficulty of escape and rescue,once if fire disaster occurs,it will result in serious casualties,huge social impact and economic losses.In addition,itwillalso lead to the bursting of concrete and the deterioration of mechanical properties and the damage to the structure in some extent due to the high temperature,which greatly reduces the bearing capacity and safety of the structure,and even cause structural damage.Therefore,it is very important to study the mechanical behavior of underground space structure in fire.Because most underground structures such as tunnels and underground integrated corridors are reinforced concrete frame structures,it is important to study the mechanical behavior of underground concrete frame structure in fire,which is important for fire protection design of underground space structure such as traffic tunnel and underground integrated corridor.In this paper,the fire behavior of underground concrete frame structure is simulated numerically on the basis of T.Ring's underground concrete frame fire test,and the following work is done as follows:(1)The fire model of underground concrete frame was established by respectively using special fire resistance analysis software SAFIR and large-scale finite element analysis software ABAQUSaccording to the experiment of T.Ring.By comparing with the experimental data,the special fire resistance analysis software SAFIR validates the advantagesin fire resistance analysis and verifies the effectiveness of the model.(2)The fire model of underground concrete frame is established by using SAFIR fire resistance analysis software.The temperature and displacement of underground concrete frame structure under fire are analyzed,and the mechanical properties such as film force and bending force are changed over time and the features of the internal force.(3)Using SAFIR fire resistance analysis software to analyze the influence of the parameters such as the reinforcement ratio of the longitudinal reinforcement,the thickness of the frame and the thickness of the concrete protective layer on the mechanical properties such as the film force and bending force of the underground concrete frame structure fire,and analyze the reasons(4)Summarize the conclusiondrawn from the numerical simulation analysis,and provide suggestions and advice for the fire protection work of the underground concrete frame structure.