受火预应力混凝土箱梁桥温度场数值模拟分析  

Numerical Simulation of Temperature Field of Prestressed Concrete Box Girder Bridge After Fire Exposure

作　　者：刘旭政[1,2] 余晨曦 饶文真 刘嘉奕 郑尚敏[1] 吴刚 LIU Xuzheng;YU Chenxi;RAO Wenzhen;LIU Jiayi;ZHENG Shangmin;WU Gang(School of Civil Engineering and Architecture,East China Jiaotong University,Nanchang 330013,China;State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure,East China Jiaotong University,Nanchang 330013,China;Fujian Provincial Transportation Research Institute Co.Ltd.,Fuzhou 350004,China)

机构地区：[1]华东交通大学土木建筑学院,江西南昌330013 [2]华东交通大学轨道交通基础设施性能监测与保障国家重点实验室,江西南昌330013 [3]福建省交通科研院有限公司,福建福州350004

出　　处：《防灾减灾工程学报》2024年第6期1377-1385,共9页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(52068026;52068025;52368073);赣鄱俊才支持计划-主要学科学术和技术带头人培养项目—领军人才(产学研类)(20243BCE51050);江西省自然科学基金项目(20232BAB204070;20232BAB204071)资助。

摘　　要：火灾下桥梁内部温度场随着时间与空间的变化规律是研究火灾作用下桥梁结构安全及抗火性能研究的基础。以一座实际受火预应力箱梁桥为例,采用火灾动力学软件FDS重构桥梁火灾场景,研究火灾作用下预应力箱梁表面温度分布规律。通过有限元软件ANSYS计算分析箱梁内部温度场,并将火灾后现场检测结果与模型计算结果进行对比分析。研究结果表明:(1)火灾作用下混凝土结构表面温度逐渐升高,高温区域集中在火源正上方的底板区域及底板边缘与腹板相交位置处,最高温度约为750℃;(2)随着火灾时间的不断增加,箱梁构件内部温度不断升高,构件温度梯度增大,底板表面最高温度为754℃,距表面20 cm深度处温度为28℃;(3)采用二次曲线拟合得出了受火箱梁距表面深度与计算温度的关系曲线,并与规范建议值进行了对比。二者温度变化趋势较为一致。但是由于温升曲线及构件尺寸的不同,其内部温度计算值与规范建议值存在一些差异;(4)现场火灾影响区域与FDS模拟箱梁底面温度场所显示的高温区域基本一致,火源上方箱梁底板、腹板位置为主要损伤区域。内部温度场的数值分析结果与现场检测推定结果基本吻合,说明采用ANSYS计算构件内部温度场具有较好的准确度。The variation of the internal temperature field of the bridge with time and space under fire is the basis for studying the safety and fire resistance of the bridge structure under fire.Taking a pre-stressed box girder bridge under actual fire as an example,the fire dynamics software FDS was used to reconstruct the fire scenario of the bridge,and the surface temperature distribution pattern of the prestressed box girder under fire was studied.The internal temperature field of the box girder was cal-culated and analyzed using finite element software ANSYS,and the post-fire field test results were compared with the model calculation results.The results showed that:1)The surface temperature of the concrete structure gradually increased under fire exposure,with high-temperature areas concentrat-ed in the bottom plate area directly above the fire source,and at the intersection of the bottom plate edge and the web,reaching a maximum temperature of approximately 750℃.2)With the continuous increase of fire time,the internal temperature of the box girder components continued to rise,and tem-perature gradient of the components kept increasing.The maximum temperature on the surface of the bottom plate was 754℃,while the temperature at a depth of 20 cm from the surface was 28℃.3)The relationship curve between the depth of the box girder from the surface and the calculated temper-ature was obtained by quadratic curve fitting,and compared with the recommended values in the speci-fication.The temperature variation trends were generally consistent.However,due to the differences in the temperature rise curve and component size,there were some differences between the calculated value of internal temperature and the recommended values in the specification.4)The fire-affected ar-ea on site was generally consistent with the high-temperature areas displayed by the FDS simulation of the box girder's bottom surface temperature field,with the main damage occurring at the bottom plate and web areas directly above the fire source.The

关 键 词：桥梁工程 火灾 数值模拟 FDS ANSYS 温度场 

分 类 号：U448.213[建筑科学—桥梁与隧道工程] U447[交通运输工程—道路与铁道工程]