温度变化对大跨度钢管混凝土拱桥徐变效应的影响

Influence of Temperature Change on Creep Effect of Long⁃span Concrete⁃filled Steel Tubular Arch Bridge

为研究在非标准恒定温度条件下主跨575 m的钢管混凝土拱桥在运营阶段拱顶截面位移和应力的时变特征,结合考虑温度影响的CEB⁃FIP(1990)徐变模型,通过控制温度参数将温度变化引入到大跨度钢管混凝土拱桥的徐变效应分析中,并与JTG 3362—2018《公路钢筋混凝土及预应力混凝土桥涵设计规范》进行对比,分析了非标准恒定温度变化对徐变的影响,以及大跨度钢管混凝土拱桥长期变形和应力状态的预测偏差。结果表明:非标准恒定温度下,温度越高,混凝土徐变引起的主拱肋拱顶截面的长期变形越大,成桥10年时钢管和管内混凝土应力的变化幅度越大。CEB⁃FIP(1990)模型计算得到的主拱跨中拱顶处长期变形最大预测偏差为8.9%,成桥后10年主拱肋跨中拱顶截面钢管和混凝土应力最大预测偏差分别为7.5%和18.7%。在大温差区大跨度钢管混凝土拱桥的徐变效应分析中,建议考虑温度变化对混凝土徐变的影响,从而为运营阶段长期时变行为的预测提供更合理的参考。

In order to study the time-varying characteristics of the deflection and stress of the vault section of a long-span concrete-filled steel tubular(CFST)arch bridge with a main span of 575 m under non-standard constant temperature conditions,based on the CEB-FIP(1990)model considering temperature effect,combined with the CEB-FIP(1990)creep model considering the influence of temperature,the temperature change was introduced into the creep effect analysis of long-span CFST arch bridge by controlling temperature parameters,and compared with JTG 3362-2018 Specifications for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts,the influence of non-standard constant temperature change on creep and the prediction deviation of long-term deformation and stress state of long-span CFST arch bridge were analyzed.The results show that under the non-standard constant temperature,the higher the temperature,the greater the long-term deformation of the vault section of the main arch rib caused by concrete creep,and the greater the change range of the stress of the steel tube and the concrete in the tube when the bridge is completed for 10 years.The maximum prediction deviation of the long-term deformation of the vault in the middle span of the main arch calculated by CEB-FIP(1990)model can reach 8.9%,and the maximum prediction deviation of the steel tube and concrete stress of the vault in the middle span of the main arch rib in 10 years after the completion of the bridge can reach 7.5%and 18.7%respectively.In the analysis of creep effect of long-span CFST arch bridge in large temperature difference area,it is suggested to consider the influence of temperature change on concrete creep,so as to provide a more reasonable reference for the prediction of long-term time-varying behavior in operation stage.