正交异性钢桥面构造细节的日照温度次应力分析  

THE SECONDARY STRESS AT THE DETAILS OF ORTHOTROPIC BRIDGE DECKS INDUCED BY THERMAL GRADIENT UNDER SOLAR RADIATION

作　　者：祝志文 桂飘[1] 滕华俊 Federico Accornero ZHU Zhi-wen;GUI Piao;TENG Hua-jun;Federico Accornero(Department of Civil and Environmental Engineering,Shantou University,Shantou,Guangdong 515063,China;School of Civil Engineering,Hunan University,Changsha,Hu’nan 410082,China)

机构地区：[1]汕头大学土木与环境工程系,广东汕头515063 [2]湖南大学土木工程学院,湖南长沙410082

出　　处：《工程力学》2022年第8期158-171,共14页Engineering Mechanics

基　　金：国家自然科学基金项目(51878269)。

摘　　要：为研究正交异性钢桥面板构造细节的日照温度次应力行为,多次在高温和强日照天气下现场实测了某自锚式悬索桥钢箱梁外周和实腹式横隔板上温度场,基于观测到的最大顶底板温差拟合了横隔板竖向温度梯度表达式;在ANSYS中建立了钢箱梁节段有限元模型并施加外周温度,计算其24 h温度场,并与横隔板实测竖向温度的对比校验了温度场模拟的合理性;开展了钢箱梁节段和子模型的精细化热应力分析,得到了纵肋-横隔板和弧形切口共4个构造细节的温度应力时程曲线。研究表明:在强太阳辐射和高温环境下,钢箱梁横向温差不明显,但存在明显的竖向温度梯度,横隔板竖向温度梯度可拟合为四折线形式,最大温差明显小于欧规值。正交异性钢桥面板产生热变形并在构造细节处产生明显热应力集中,特别是弧形切口热应力大。仅日照竖向温度梯度作用,或仅桥面货车通行加载,弧形切口均为无限疲劳寿命;但二者共同作用产生的应力幅,大于构造细节的常幅疲劳极限,可能是该构造细节出现疲劳开裂的原因。To investigate the secondary stress at the details of orthotropic steel decks(OSD)induced by thermal gradient in steel box girders,the temperature field of the steel box girder of a self-anchored suspension bridge is measured for multiple times under high environmental temperature and strong solar radiation.The vertical temperature gradient is fitted based on the measured maximum temperature difference between the roof and the floor.After establishing the sectional box girder model in ANSYS with the measured temperature applied on the box-girder surface,the temperature field in the sectional model is obtained.The temperature results on the floor beam agree well with the measured temperature,which validate the thermal analysis.Based on the simulated 24 h temperature field,the thermal stress field in the sectional box girder is first analyzed.Refined stress results are obtained based on a sub-model technology.The thermal stress time histories are determined at the four details around rib-to-floor beam(RF)connection and the cutout detail.It is found that,under strong solar radiation and high environmental temperature,the transverse temperature difference in the steel-deck box girder is not apparent,while the vertical thermal gradient is significant and can be fitted as a four-broken-line function with the maximum temperature difference lower than that of the Eurocode.Significant stress concentration appears at the details of the OSD,particularly at the cutout detail.The cutout detail will be fatigue-free if the thermal stress range resulting from the vertical temperature under solar radiation is considered,or if the stress range resulting from the truck loading is considered.The stress range at the cutout detail,which is jointly produced by the thermal effect of the vertical temperature and by the truck loading,is larger than the constant-amplitude fatigue limit and may contribute to the fatigue crack at the cutout detail.

关 键 词：钢箱梁 温度场 构造细节 热应力 疲劳 现场实测 有限元分析 

分 类 号：U445.71[建筑科学—桥梁与隧道工程]