预制T梁架设阶段横向温度梯度作用侧向变形研究

Lateral Deformation of Precast Concrete T-Girder Under Transverse Temperature Gradient During Erection

为控制大跨预制混凝土T梁架设阶段由横向温差导致的侧向失稳,以标准截面预制混凝土T梁为背景,对架设阶段横向温度梯度作用下的T梁侧向变形进行研究。建立截面热传递理论模型,通过热传递有限元分析得到主梁温度时程与分布,并与实测结果对比以验证有限元分析准确性,分析极端环境条件下(最高气温、最低气温、最大温差和最强太阳辐射)截面横向温度梯度分布,提出横向温度梯度多线性分布模式和预制混凝土T梁在横向温度梯度作用下的侧向变形简化分析方法。结果表明:热传递有限元分析计算结果与实测结果吻合;混凝土T梁顶、底板温差明显,且均产生较大的横向温度梯度;顶、底板及腹板的最高温度均出现在太阳直射边缘,最低温度出现在横向中心位置附近;采用简化分析方法计算预制混凝土T梁在横向温度梯度作用下的侧向变形,并得到不同标准截面梁在极端横向温度梯度下的侧向变形与跨径的关系,可为预制混凝土T梁架设时侧向变形控制提供参考。

This study focuses on the lateral deformation of T-girder under transverse temperature gradient during erection process.Taking the precast concrete T-girder of typical cross-section as the basis,the measures to control the lateral instability of the long-span T-girder induced by transverse temperature gradient at the erection stage are proposed.The theoretical model to calculate cross-sectional heat transfer was established,and the temperature time history of and temperature distribution in the main girder was numerically simulated,afterwards,the theoretical and simulated values were compared with the measured values to verify the finite element analysis.The cross-sectional temperature gradient distribution in extreme environments(including extreme high and low temperatures,maximum temperature difference,and strongest solar radiation)was analyzed,based on which a multi-linear distribution mode of transverse temperature gradient as well as the simplified methods to analyze the lateral deformation of the precast concrete T-girder under transverse temperature gradient were presented.It is shown that the simulated heat transfer analysis agrees with the measured results.There exists significant temperature difference between the top and bottom slabs of the concrete T-girder,and both of which bear great transverse temperature gradients.The highest temperatures in the top and bottom slabs and webs all appear on the surfaces directly exposed to sunlight,while the lowest temperatures appear in the vicinity of the transversal center.The proposed simplified method is applied to calculate the lateral deformation of the precast concrete T-girder under transverse temperature gradient,and the relationship between lateral deformation and span length of T-girder with different typical cross-sections under extreme transverse temperature gradient was figured out.This paper provides a case for the study of lateral deformation control of precast concrete T-girder during erection.