Abstract: Non-uniform shrinkage of concrete box-girder cross-section has remarkable effect on the long-term structure behavior, which hasnt been solved till now. Based on the mechanism of drying shrinkage deformation of concrete and the characteristics of long-term shrinkage deformation of long-span PC box girder bridges, a new idea to control the long-term non-uniform shrinkage deformation of PC box girder bridges by setting a sealing coating on the surface of the structure was proposed. The rationality and reliability of the proposed method was verified by model test, in which factors such as the shape size of the structure, the water-cement ratio of concrete and the way of sealing coating were considered comprehensively. Taking the Jiangjin Yangtze River Bridge as an example, the test design of sealing coating was carried out, and the sensitivity analysis of environmental humidity, painting time and other parameters was carried out. The analysis results show that the drying shrinkage deformation can be effectively reduced and the direction of structural shrinkage and flexure deformation can be controlled by setting a sealing coating on the surface of box girder.

Key words: bridge enginering, concrete box girder bridges, sealing coating, non-uniform shrinkage, long-term structure behavior, control of shrinkage deformation

摘要： 混凝土箱梁截面不均匀收缩对结构长期行为影响显著，但目前尚无有效控制方法。从混凝土干燥收缩变形机理出发，针对大跨度PC箱 梁桥长期收缩变形特征，提出一种通过结构表面设置封闭涂层的收缩变形控制新思路，实现PC箱梁桥长期不均匀收缩变形控制。模型试验验 证了该方法的合理性及可靠性，试验中综合考虑结构外形尺寸、混凝土水灰比及封闭涂层方式等因素。以江津长江大桥为例，开展了封闭涂 层试设计，并进行了环境湿度、涂装时间等参数敏感性分析。分析结果表明：通过在箱梁表面设置封闭涂层可以有效降低结构干燥收缩变形 、控制结构收缩挠曲变形方向。

关键词: 梁桥工程, 混凝土箱梁桥, 封闭涂层, 不均匀收缩, 长期结构行为, 收缩变形控制