Numerical simulation study on temperature characteristics of double-deck suspension bridge in vehicle fires

Knowledge of the temperature response of load-bearing structures in suspension bridges under vehicle fires is a prerequisite for fire protection measures. In this study, a double-deck suspension bridge was adopted as the engineering background. The temperature response of the main cables and slings was examined in the case of a fire on the upper vehicle deck, and the temperature characteristics of load-bearing structures such as trusses and the roof plate were investigated on the lower vehicle deck. The simulation variables included heat release rate (HRR), fire location, and ambient wind speed. The results showed that: (1) The fire temperature rose as HRR increased, and the fire temperature was inversely proportional to the wind speed. (2) When a fire occurred on the upper bridge deck, the maximum width of the high-temperature area on the main cable was 15 m, and the maximum temperature was 1040 °C. (3) When a fire occurred on the lower bridge deck, the maximum temperature of the truss was 1209 °C, and the maximum height of the high-temperature area exceeding 300 °C was 7.6 m. The maximum temperature reached in a 200 MW oil tanker fire was 1344 °C, lasting 3650 s.