基于地区的温度实测数据，采用4种常用的概率分布模型对桥址区不同季节日温度极值分布进行拟合，通过5项拟合指标评价各概率分布模型的拟合优劣，并选取最优概率分布模型。基于最优概率分布模型，进一步推算出桥址区重现期分别为20、50、100 a的温度极大值和极小值。采用ANSYS有限元软件建立某大跨度钢箱梁悬索桥有限元模型，并研究考虑极端温度下不同构件升降温对桥梁自振频率和位移的影响。进一步研究中央扣、竖向支座和伸缩缝等约束体系对桥梁温致效应的影响。结果表明：全桥自振频率除加劲梁一阶对称横弯频率外，其余的频率与全桥的温度呈负相关；悬索桥的桥塔和加劲梁分别升、降温25℃时，桥梁各阶自振频率变化量都在5%以内；悬索桥主缆降温12℃时，导致加劲梁反对称竖向振动频率的显著增加，约为12%。此外，加劲梁纵向竖向位移响应及桥塔竖向和纵桥向位移响应与桥梁温度变化的呈线性相关性，且加劲梁的纵向位移受加劲梁的温度变化影响最大，建水测和元阳侧纵向位移变化率分别为4.7、3.3 mm/℃。加劲梁梁端竖向位移和转角主要受到主缆温度变化的影响。竖向支座和伸缩缝纵向限位装置对桥梁的温致位移响应影响可忽略不计，但中央扣会使桥梁跨中处短吊杆的内力发生突变。

Based on the regional measured temperature, four common probability distribution models were proposed to fit the probability distribution of the daily temperature extremes in different seasons at the bridge location. The fitting of each model was evaluated through 5 performance indexes and the optimal probability distribution model was selected. Based on the optimal probability distribution model, the maximum and minimum temperature values with the return periods of 20 a, 50 a, and 100 a at the bridge location were calculated subsequently. The finite element model of a long-span steel box girder suspension bridge was established using ANSYS. Based on the established model, the effects of temperature variation of different structural components on the bridge's natural frequency and displacement was studied considering the extreme temperature. The influence of restraint systems such as central buckle, vertical supports and expansion joints on the temperature-induced effect of the bridge was further studied. The investigated results show that, except for the first-order symmetrical transverse bending frequency of the stiffening girder, the natural frequencies of the others are negatively correlated with the temperature of the full bridge; When the temperature of the pylons and stiffening girder of the suspension bridge rises or falls by 25℃ respectively, the changes in the natural frequency are all within 5%; When the temperature of the main cable of the suspension bridge is reduced by 12℃, the anti-symmetric vertical vibration frequency of the stiffening girder will increase significantly by about 12%; In addition, the vertical displacement response of the stiffening girder and the vertical and longitudinal displacement response of the bridge tower are linearly related to the temperature variation. And the longitudinal displacement of the stiffening girder is mainly affected by the temperature variation of the stiffening girder. The longitudinal displacement rate of Jianshui side and Yuanyang side are 4.7 mm/℃ and 3.3 mm/℃, respectively; The vertical displacement and rotation angle of the stiffening girder ends are mainly affected by the temperature variation of the main cable; The influence of the vertical support and the longitudinal limit device of the expansion joint on the temperature-induced displacement response of the bridge is negligible, but the central buckle will cause a sudden change in the internal force of the short suspender at the middle of the bridge.

U448.25

中国博士后科学基金（2019M663554、2019TQ0271）；四川省科学技术厅科技计划（2020YJ0080）