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采用数值模拟方法,研究钢-混凝土组合梁式公路桥在大型车辆火灾下的结构响应,考察桥梁形式、火灾工况及荷载比的影响。首先以规范给定的烃类火灾升温曲线及CFD模拟实际油罐车火灾所得到的升温曲线作为温度边界条件,用ABAQUS建立了8个有限元模型进行计算,得出了构件内部温度场,发现实际火灾下斜交桥受火跨最高温度低于正交桥的,但整体温度更高;实际火灾较规范火灾下结构升温更快,最高温度更高;随后以受火升温结果作为温度荷载,通过恒载升温分析,考察了共计18个案例的结构响应,发现正交桥和斜交桥在火灾下的破坏模式有较大差别,前者出现不适于继续承载的变形,同时伴随着远端支座腹板屈曲的局部破坏,而后者主要体现为远端支座腹板严重屈曲;最后提出了针对钢-混凝土组合梁桥抗火措施和设计思路的建议。
The numerical simulation method is used to study the structural response of steel-concrete composite beam-type highway bridges under fires of large vehicles. The effects of bridge form, fire conditions and load ratio are investigated. Firstly, using the temperature rise curve obtained from the given hydrocarbon fire curve and the CFD simulation of real tanker fire as the temperature boundary conditions, eight finite element models were established by ABAQUS, and the internal temperature field was found. Under the actual fire, the maximum temperature of the cross-over fire bridge is lower than that of the orthogonal bridge, but the overall temperature is higher; the actual fire is warmer and the highest temperature is higher than that of the normal fire; then the result of temperature rise by fire is taken as the temperature load, Through the analysis of constant temperature and temperature, the structural responses of a total of 18 cases were investigated. It is found that the failure modes of the orthogonal and skewed bridges are quite different under the fire. The former is not suitable for the deformation of the bearing and the other is accompanied by the distal branch The local buckling of the seat web was destroyed, while the latter was mainly manifested by the severe buckling of the webs of the distal abutment. Finally, some suggestions were put forward for the fire-resistant measures and design ideas of the steel-concrete composite girder bridge.