火灾后混凝土桥梁结构安全初步评估方法  

Preliminary safety assessment method for concrete bridge structure after fire exposure

作　　者：刘旭政[1] 李任福 余晨曦 郭河 LIU Xu-zheng;LI Ren-fu;YU Chen-xi;GUO He(School of Civil Engineer and Architecture,East China Jiaotong University,Nanchang 330013,China;Hangzhou Dingqiao Hospital,Hangzhou 310044,China;Fujian Provincial Transportation Research Institute Co.,Ltd.,Fuzhou 350004,China;China Communications Construction Road&Bridge Inspection and Maintenance Co.,Ltd.,Beijing 101301,China)

机构地区：[1]华东交通大学土木建筑工程学院,江西南昌330013 [2]杭州市丁桥医院,浙江杭州310044 [3]福建省交通科研院有限公司,福建福州350004 [4]中交路桥工程检测股份有限公司,北京101301

出　　处：《广西大学学报（自然科学版）》2022年第1期62-73,共12页Journal of Guangxi University（Natural Science Edition）

基　　金：国家自然科学基金项目(52068026,52068025,51968024)。

摘　　要：针对目前火灾后桥梁结构的安全评定尚无可依据的标准和规范的现状。为了建立火灾后桥梁结构安全的初步评估方法,基于流体动力学软件FDS,研究分析不同火源面积和梁底距燃烧物高度对于梁底温度场的影响。结果表明:①不同的梁底距燃烧物高度下,当火源面积超出其临界面积后,中心测点的温度与火源面积大小无关;②由于大气环境中燃烧火焰的自身构造使得梁底最高温度与桥下火源各层焰火的燃烧高度有关,因此不同火源面积下的梁底距燃烧物高度与梁底最高温度变化趋势并不统一;③受火梁底的低、中、高温度区域的面积占比可偏安全地划分为55%、30%和15%。最后,以某实际受火预应力混凝土桥梁的灾后现场检测结果与本文的评估结果进行对比,验证本文提出火灾后桥梁结构安全初步评估方法的有效性。At present,there are no standards nor specifications for the safety assessment of bridge structures after fire exposure.Based on the fluid dynamics software FDS(fire dynamic simulation),with piled wood or textile materials as the combustion materials,the temperature field at the bottom of the fired beam under various fire source areas and heights from the combustion material is analyzed.Furthermore,a set of the preliminary assessment method of bridge structure safety after the fire was established.The research results show that:1)When the fire source area exceeds its critical area with various heights from the bottom of the beam to the burning material,the temperature at the central measuring point is independent from the fire source area.2)Due to the combustion flame structural relationsin the atmosphere,the maximum temperature at the bottom of the beam is related to the burning height of each layer of the fire source under the bridge.Thus,the maximum temperature of the beam bottom is inconsistent with the height from the beam bottom to the combustion source.3)The area of the low,medium,and high-temperature areas at the bottom of the fired beam can be conservatively divided into 55%,30%,and 15%,respectively.Finally,the post-disaster site inspection results of an actual fired prestressed concrete bridge are compared with the evaluation results of this paper,which verifies the effectiveness of the preliminary post-fire evaluation method proposed in this paper.

关 键 词：桥梁工程 桥梁火灾 安全评估 火灾动力学模拟 火源燃烧物 

分 类 号：U447[建筑科学—桥梁与隧道工程]