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以江苏省内某高速公路预应力混凝土空心板桥的突发性火灾为研究对象,阐述了火灾高温对混凝土、钢筋和钢绞线力学指标的影响,总结了火灾现场温度的判定方法,提出了桥梁火灾仿真分析与评估的实施步骤。通过火灾燃烧物性质分析,选择了Eurocode烃类火灾升温曲线,论述了火灾下混凝土爆裂机理,在此基础上建立了空心板混凝土与内腔封闭孔洞内空气的流固耦合传热模型,并进行了火灾温度场有限元仿真分析。根据有限元计算结果,比较了火灾作用下底板混凝土爆裂对空心板温度场的影响,最后结合火灾后材料性能的变化对板梁火损状况进行了综合评估。
Taking the sudden fire of a prestressed concrete hollow slab bridge in a highway in Jiangsu Province as the research object, the influence of high temperature on the mechanical indexes of concrete, steel bar and strand is expounded, and the method of determining the temperature on fire scene is summarized. Bridge fire simulation analysis and evaluation of the implementation steps. Based on the analysis of the properties of the combustion products of fire, the Eurocode hydrocarbon fire heating curve was selected, the burst mechanism of concrete under fire was discussed, and the fluid-solid coupling heat transfer model between the hollow concrete and the air in the closed cavity was established. Finite element simulation analysis of fire temperature field. According to the results of finite element analysis, the influence of fire burst on the temperature field of hollow slab is compared. Finally, the fire damage status of slab beam is evaluated based on the change of material properties after fire.