危险火灾场景下铁路钢桥温度场和极限承载力研究

Research on Temperature Field and Ultimate Bearing Capacity of Railway Steel Bridge in Dangerous Fire Scene

选择典型铁路桥梁64 m单线钢桁梁为研究对象,对其火灾作用下的温度场分布情况和力学行为进行分析。基于桥梁结构特点,分析可能发生的火灾场景,确定桥面列车火灾为危险场景,并提出温度场升温曲线。通过危险火灾场景下的升温曲线对钢桁梁桥温度场进行分析,发现构件受火时间超过25 min时的温度基本接近火灾烟气温度;将桥梁温度场赋予到力学有限元模型中进行力学分析,发现受火约38 min时钢桁梁达到极限破坏状态,耐火极限较小。

The typical 64 m single track steel truss of railway bridge was selected as the research object to analyze the temperature field distribution and mechanical behavior under the action of fire.Based on the structural characteristics of the bridge,the possible fire scenes were analyzed and the train fire on the bridge deck was determined as the most dangerous scene,and the temperature rise curve was proposed.The temperature field of the steel truss bridge was analyzed by the temperature rise curve in the dangerous fire scene.It is found that the temperature of the component is close to the temperature of the fire smoke when the fire time is more than 25 min.The temperature field of the bridge was given to the mechanical finite element model for mechanical analysis.It is found that the steel truss bridge reaches the ultimate failure state when the fire time is about 38 min,and the fire resistance limit is small.