油池火灾下空心板通道桥温度场及结构损伤分析
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华东交通大学土木建筑学院

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Analysis of Temperature Field and Structural Damage of Hollow Slab Channel Bridges under Oil Pool Fire
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    摘要:

    【目的】研究油池火灾下空心板通道桥梁底温度场分布及结构损伤特征。【方法】利用FDS分析不同油池火灾场景下空心板通道桥梁底温度场分布,利用ABAQUS对所有火灾场景中最不利的空心板梁进行热传导分析,获取梁体内部温度场,最后利用基于强度折减的虚拟层截面等效原理,计算其火灾损伤程度。【结果】空心板通道桥跨径越小、桥下净高越大、油池面积越大,梁底温度越高;梁底宽度对梁底温度场的影响不显著;在风速较小时,梁底最高温度会升高,但风速过大时,火焰被吹出通道桥,导致梁底温度变低。火灾场景V-2下10#梁底绝热温度出现最大值,达到1 440 ℃。不同受火时间下10#梁跨中截面温度场呈现平行于受火面的层状分布,在受火180 min时,梁底混凝土和底板钢绞线的最高温度分别达到1 417 ℃和718 ℃,底板混凝土合计烧损深度达到7.94 cm,钢绞线S1和钢筋S3的剩余强度仅为96 MPa和19 MPa。根据钢绞线、钢筋和混凝土虚拟层的损伤数据,分阶段建立了油池火灾下空心板梁跨中截面抗弯承载力保有率的预测公式。【结论】研究结果可为通道桥的灾后评定、加固和修复方案制定、防火措施研究等方面提供参考。

    Abstract:

    【Objective】To study the temperature field distribution and structural damage characteristics of hollow slab channel bridges under oil pool fire scenarios.【Method】FDS was used to analyze the temperature field distribution at the bottom of hollow slab channel bridge under different oil pool fire scenarios.ABAQUS was used to conduct heat conduction analysis on the most unfavorable hollow slab girder in all fire scenarios, and the internal temperature field of the girder was obtained. Finally,based on the equivalence principle of cross sectional virtual layer due to the reduction of the strength,the fire damage degree was calculated.【Result】The smaller the span of hollow slab channel bridge, the larger the bridge vertical clearance and the larger the area of the oil pool, the higher the temperature at the girder bottom.The influence of girder bottom width on temperature field of girder bottom is not significant. When the wind speed is small, the maximum temperature at the girder bottom will increase, but when the wind speed is too large, the flame will be blown out of the channel bridge, resulting in lower temperature at the girder bottom. In the fire scenario V-2, the adiabatic temperature at the bottom of 10# girder reaches the maximum value, at 1 440 ℃. Under different fire times, the temperature field of the mid-span section of 10# girder presents a layered distribution parallel to the fire exposure surface. When the fire-exposure time reaches 180 min, the maximum temperature of the concrete at the girder bottom and the steel strand at the bottom slab reach 1 417 ℃ and 718 ℃ respectively, the total burning depth of bottom slab concrete reaches 7.94 cm, and the residual strengths of steel strand S1 and steel bar S3 are only 96 MPa and 19 MPa. According to the damage data of steel strands, steel bars and concrete virtual layers, the prediction formula of flexural capacity retention rate of hollow slab girder under oil pool fire is established in stages.【Conclusion】The research results can provide reference for the post-disaster assessment, formulation of plans to reinforcement and repair, and fire prevention measures research of the channel bridges.

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  • 收稿日期:2025-01-11
  • 最后修改日期:2025-03-02
  • 录用日期:2025-04-01
  • 在线发布日期: 2026-06-05
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