Numerical Analysis of Ultimate Mechanical Characteristics of Suspension Bridges’s Cable in High Temperature Fire

Abstract

Relying on the joint research project, research is carried out on the ultimate mechanical characteristics of suspension bridge slings under high temperature fire. The establishment of a local transient temperature field heat transfer model based on the FDS software, and the analysis of the temperature distribution law of the fire source at different wind speeds. The most unfavorable fire condition is the combination of the fire source heat release rate of 300MW and the wind speed of 14m/s; the overall structure model of the bridge is modeled by ANSYS software. Firstly, the modal analysis of the whole bridge model is carried out to verify the accuracy of the modeling, and then the thermal structural coupling analysis is carried out under the most unfavorable fire conditions to obtain the structural response of the whole bridge structure under the sling fire. According to the change trend of the structure response of the cable under fire, the fire resistance limit of the bridge structure is obtained as 460°C; Under the most unfavorable fire burning situation, when the limit number of broken cable in the span is 3, the cable will be caused into collapsing continuously; the composite protective layer has a significant effect on the fire resistance of the cable.