Fire-induced temperature response of main cables and suspenders in suspension bridges: 1:4-scaled experimental and numerical study

As traffic increases, vehicle fires on suspension bridges present significant threats to structural integrity and traffic safety. This study, centered on a suspension bridge in China, investigates the thermal responses of main cables and suspenders during vehicle fires using 1:4 scale gasoline pool fire experiments and numerical simulations. The study examines the effects of wind speed, pool size, and lane position on flame dynamics and the temperature response of cables. The results demonstrated that higher wind speeds and larger pool sizes enhance the mass burning rate, leading to flame deflection and uneven temperature distribution along the cables. Under a wind speed of 1.56 m/s, the emergency lane fire generated a maximum temperature of approximately 960 °C at the base, while the slow lane fire reached 909 °C at a height of 1.6 m. These findings highlight the greater thermal threat posed by emergency lane fires. A fire protection zoning strategy is proposed: the 0-12.8 m zone should be protected with a target temperature of 1000 °C, and the 12.8-20.8 m zone with a target of 700 °C, with a fire resistance duration of 90 minutes. This research provides a critical reference for the fire protection design of suspension bridge cables.