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桥塔结构火灾温度荷载模型及效应分析

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为研究火灾对桥塔结构的影响,提出桥塔近火面的火灾温度荷载模型,并对全塔结构的火灾效应进行分析.以高345 m的钢-混组合桥塔作为研究对象,设定7种火灾场景,采用火灾动力学仿真软件(fire dynamics simulator,FDS)获取不同火灾场景下桥塔近火面的温度分布.基于距离和高度参数建立近火面火灾温度荷载模型公式.以温度荷载模型为输入,计算获得桥塔壁面内部的瞬态温度场,通过顺序耦合力场分析桥塔在火灾下的力学性能.研究结果表明:火源与塔面距离较近时,火焰会发生贴壁现象,近火面温度较高且温度沿着桥塔高度方向逐渐降低;火源与塔面距离较远时,近火面整体温度较低,桥塔倾斜使近火面的最高温度出现在火焰距离桥塔最近高度上;在桥塔厚度方向,温度沿着厚度方向迅速降低且温度上升起点逐渐滞后;不同火灾场景下桥塔的最大应力取决于近火面温度,应力集中在近火面温度较高的区域;随着火灾的发展,应力集中区域由高温区域逐渐向低温区域发展;近火面温度较低时,热膨胀效应会引起桥塔发生远离火源方向的侧向位移,而温度较高会导致近火面及其内部材料的承载能力大幅下降,侧向位移靠近火源方向发展;桥塔施工期间发生火灾引起的侧向位移较运营期间更小.
Fire temperature load model and influence analysis of bridge tower structure
In order to study the influence of fire on the bridge tower,the fire temperature load model of the near-fire surface of the bridge tower was proposed,and the fire effect of the whole tower structure was analyzed.The steel-concrete composite bridge tower with a height of 345 m was used as the research object,seven fire scenarios were set up,then,the temperature distribution of different fire scenarios was obtained by fire dynamics simulator(FDS).Based on the distance and height parameters,the temperature load model formula of near-fire surface fire was established.The temperature load model was used as input,and the transient temperature field within the wall of the bridge tower was calculated.Furthermore,the mechanical properties of the bridge tower under fire were analyzed by sequential coupling force field.The results show that when the distance between the fire source and the tower surface is close,the flame will stick to the wall,the temperature near the fire surface is higher and the temperature gradually decreases along the height of the tower.When the distance between the fire source and the tower surface is far,the overall temperature of the near-fire surface is low.The inclination of the bridge tower makes the highest temperature of the near-fire surface appear at the height of the flame closest to the bridge tower.In the thickness direction of the bridge tower,the temperature decreases rapidly along the thickness direction and the starting point of temperature rise gradually lags behind.The maximum stress value of the bridge tower under different fire scenarios depends on the temperature of the near-fire surface,and the stress is concentrated in the area where the temperature of the near-fire surface is high.With the development of fire,the stress concentration area gradually develops from high temperature area to low temperature area.When the temperature near the fire surface is low,the thermal expansion effect will cause the lateral displacement of the bridge tower away from the fire source direction,while the high temperature will lead to a significant decrease in the bearing capacity of the near-fire surface and its internal materials,and the lateral displacement develops near the fire source direction.The lateral displacement caused by fire during tower construction is smaller than that during operation.1 tab,13 figs,30 refs.

bridge engineeringbridge towertemperature load modelfire dynamicsfire effecttemperature field

王佐才、郭战、徐京海、李阳、辛宇

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合肥工业大学土木与水利工程学院,安徽合肥 230009

安徽省道路与桥梁检测工程研究中心,安徽合肥 230009

中国铁路上海局集团有限公司,上海 200071

桥梁工程 桥塔 温度荷载模型 火灾动力学 火灾效应 温度场

国家自然科学基金项目

52278301

2024

长安大学学报(自然科学版)
长安大学

长安大学学报(自然科学版)

CSTPCD北大核心
影响因子:1.011
ISSN:1671-8879
年,卷(期):2024.44(4)