结合梁桥面板混凝土收缩应力评定

Evaluation of Concrtet Shrinkage Stress of Composite Giredr Deck Slab

灌河大桥为钢-混结合梁斜拉桥。为分析该桥桥面板混凝土收缩应力水平,分别通过试验测定和理论计算公式,得到混凝土前期收缩应变时程曲线和弹性模量时程曲线,根据收缩应变结果进行有限元模拟,得到混凝土前期和后期收缩应力,并对结合梁桥面板混凝土的收缩应力进行评定。结果表明:灌河大桥桥面板混凝土前期收缩量和收缩应力的试验结果大于JTG D62-2004规范公式计算结果;采用杆系模型得到桥面板混凝土顺桥向后期收缩应力最大值为1.5MPa,采用板壳模型得到桥面板混凝土应力最大值顺桥向为1.5MPa、横桥向为2.2MPa,需要采取有效措施以减小桥面板的收缩应力。

The Guanhe River Bridge is a steel and concrete composite girder cable-stayed bridge. To analyze the concrete shrinkage stress levels of the deck slab of the bridge, the timehistory curves of the early concrete shrinkage strain and elastic modulus were obtained, respectively using the test measurements and the theoretic calculation formulae. Based on the measure- ments of the shrinkage strain, the corresponding finite element simulation was conducted, the early and late concrete shrinkage stress was obtained and the concrete shrinkage stress of the deck slab of the bridge was evaluated. The results of the evaluation show that the test measurements of the early concrete shrinkage amount and shrinkage stress of the deck slab are greater than those calculated by the formulae in the code JTG D62-2004. The maximum value of the late concrete shrinkage stress in the longitudinal direction of the bridge obtained by the link model is 1.5 MPa while the maximum value of the late concrete shrinkage stress in the longitudinal direction of the bridge obtained by the plate and shell model is 1.5 MPa and in the transverse direction of the bridge is 2.2 MPa. As for the evaluation of the shrinkage stress, the effective measures should be taken to reduce the stress.