Numerical Analysis And Capacity Evaluation Of Slab Bridge After Fire

Since the reform and opening up,China's economy has made rapid development,and the development of the transport industry is the basis of economic progress,with the increase in the number of transport vehicles,logistics and transport density increasing,the probability of traffic accidents gradually increased.As an important part of highway,bridge fire often happens in recent years,and accidents happen suddenly,which is difficult to rescue.The high temperature of fire will damage the mechanical properties of concrete and steel,and affect the bearing capacity of the bridge.The fire of a middle bridge in Bao Ding-Fu Ping expressway is taken as the background,combined with the damage data of the bridge after fire,the numerical simulation software ANSYS is used to simulate the fire process of concrete hollow slab beam.The distribution of temperature field,stress distribution and deflection of component section under temperature load are analyzed.The mechanical properties of damaged component are studied,and the bearing capacity of damaged bridge is evaluated.The main research contents are as follows:(1)According to the the detection data of fire bridge damage,the damage mechanism of concrete,residual compressive strength,thickness of damage layer and damage of asphalt material of bridge pavement under high temperature fire are analyzed.(2)Based on the research results of domestic and foreign scholars on the thermal parameters of concrete and reinforcement,the modeling parameters required to simulate the fire-damaged bridge are determined,and the change rules of the mechanical properties of reinforced concrete members after high temperature are further analyzed.(3)The fire process of concrete hollow slab bridge was simulated and analyzed,and the temperature field,stress distribution and deflection changes of the section under different working conditions were considered under thermal analysis and thermal-structural coupling.The actual damage and simulation software results were compared and analyzed,and the correlation between them was obtained.(4)Based on the simulation results of component section temperature field,combined with the change law of mechanical properties of reinforcement and concrete under high temperature,combined with the modified formula of mechanical properties reduction of hollow slab section material,the mechanical properties of hollow slab members after fire damage were evaluated.(5)The bearing capacity,Section Deflection and maximum crack width of reinforced concrete hollow slab bridge damaged by fire are evaluated and checked by using the mechanical properties of hollow slab material after reduction.The damage condition of concrete hollow slab bridge is judged by fire high temperature.