Abstract: To investigate the fire hazard of Beijian Bridge considering real fire condition,research on the fire resistance of wood arch bridges was conducted based on fire dynamics analysis method and structural finite element method.Based on the analysis of fire dynamics,the temperature time history curves of various parts of the Beijian Bridge considering real fire condition were determined.The variation law of carbonization depth of wood members with fire time was determined based on the thermodynamic analysis results of wood members.The mechanical performance analysis of the Beijian Bridge under fire was carried out by using the effective section method,and the variation law of deflection of fire components regarding fire exposure time was determined.The calculation results indicated that after being exposed to fire for 15 minutes,the temperature of most measuring points on the upper part of the bridge reached its peak temperature,exceeding 300℃.Under the same fire exposure time,the temperature at the upper and lower parts of the bridge was lower than the temperature corresponding to the ISO 834 standard fire temperature history curve.The analysis of the mechanical performance of the Beijian Bridge under real fire showed that when subjected to fire for 20 minutes,the vertical deflection of the wood members of the Beijian Bridge was 32.6mm,exceeding 1/250 of its span,and the bridge reached its fire resistance.The reduction of the cross-section of wood members caused by real fires was the main reason for the ultimate failure of the Beijian Bridge.