苏通大桥连续刚构收缩徐变效应的不确定性分析

UNCERTAINTY ANALYSIS OF CREEP AND SHRINKAGE EFFECT IN CONTINUOUS RIGID FRAME OF SUTONG BRIDGE

收缩和徐变是混凝土材料的固有特性,其影响因素众多,具有时变性和不确定性。大跨径预应力混凝土连续刚构是对混凝土收缩和徐变较为敏感的结构,正确地预测大跨径连续刚构的收缩徐变效应具有重要的现实意义。采用现桥规中收缩徐变模型的形式,以苏通大桥连续刚构所用高强高性能混凝土收缩徐变试验为基础,提出了修正的收缩徐变预测模型,其预测值与试验值吻合较好。介绍了结构收缩徐变效应的不确定性分析方法,在数值模拟中采用了拉丁超立方抽样方法,减少了抽样次数。基于修正的收缩徐变模型,对苏通大桥连续刚构收缩徐变效应进行了不确定性分析,应用于苏通大桥连续刚构的施工阶段计算,并和实桥监控结果进行了比较。最后预测了苏通大桥连续刚构带有一定置信水平的长期变形区间。

The creep and shrinkage are inherent characters of concrete, with many influencing factors, time-dependence and uncertainty. Long-span prestressed concrete continuous rigid framed bridges are sensitive to their creep and shrinkage. It is very important to accurately estimate and predicate the creep and shrinkage effect in long-span continuous rigid framed bridges. Based on a creep and shrinkage prediction model in the code for the bridge design and the experimental research on the creep and shrinkage of the high-strength and high-performance concrete used in the continuous rigid frame of Sutong Bridge, a revised prediction model for the concrete creep and shrinkage was presented. The results show that the accuracy of the prediction of the creep and shrinkage increases significantly. Subsequently, the probabilistic analysis method of the structural creep and shrinkage effect was studied. Moreover, Latin Hypercube Sampling Method was adopted to improve the sampling precision and decrease sampling number in random simulations. The uncertainty analysis of time-dependent effects in the continuous rigid frame of Sutong Bridge was performed using the revised model, and the calculated values were compared with measured results in the construction stage. At last, time-dependent deformations due to the concrete creep and shrinkage were analyzed.