中文摘要：

预应力混凝土箱梁桥以其良好的结构整体受力性能在现代大跨桥梁结构中得到广泛应用,但迄今所修建的混凝土箱梁桥中,运营阶段箱梁开裂及下挠过大的现象较为普遍,实际混凝土箱梁桥中混凝土收缩徐变作用及其效应认识的不足是其可能产生的原因之一。现行有关混凝土收缩徐变的计算公式多以试验室模型试验结果为依据确定,由于实际混凝土箱梁结构的尺寸较大同时又处于复杂的自然环境中,因此对实际结构进行长期测试以获得能够验证现行规范混凝土收缩徐变计算公式的实测数据显得尤为重要。结合某高速公路上两座大跨预应力混凝土箱梁桥的修建及运营,对处于自然环境中的箱梁桥在混凝土收缩徐变作用下的真实反应进行测试,并详细地分析各测试数据,在此基础上提出同时考虑混凝土温度、环境相对湿度、箱梁局部理论厚度等因素及其变化的混凝土收缩应变和徐变系数计算方法,并将其应用于实际桥梁的收缩徐变效应分析中,得出一些具有实用价值的结论,为实际箱梁桥的收缩徐变计算提供参考。

英文摘要：

Concrete box girders have been widely used for long-span bridges due to the advantageous structural behavior. However, because of shrinkage and creep effects, cracking and excessive mid-span sag still exist in many prestressed concrete bridges during construction or service. Because of the large size of concrete box girder and the complex natural environment, it is particularly important to revise the shrinkage and creep models of concrete based on laboratory tests and field measurements. For two long-span prestressed concrete box girder bridges, long-term field measurements were conducted for the structure behaviors under the shrinkage and creep effects of concrete. Based on the test data, a method is developed for the calculation of the shrinkage strain and creep coefficient, taking into consideration of the temperature of concrete, the relative humidity of the environment, the thickness of girder, etc. A detailed analysis of the box girder bridges under the shrinkage and creep effects is conducted to arrive at conclusions for design references.