大跨度混凝土拱桥原型与模型时变行为对比

Time-dependent behavior comparison of long-span concrete arch bridge between prototype and model

北盘江大桥为一座主跨为445 m,矢高为100 m的无铰拱桥,是中国已建的最大跨度劲性骨架混凝土拱桥。为研究该桥施工过程的合理性和成桥后的长期性能,开展了模型试验研究,但当考虑长期性能后,原型和模型桥测试的变形和应力比例不符合线弹性比例关系。因此,本文建立了原型桥与模型桥的三维有限元模型,用实测数据验证有限元模型的正确性;对比了原型桥与模型桥在弹性和考虑温度与收缩徐变耦合效应后的位移、应力结果,并对其长期变形行为进行参数分析。研究结果表明:当考虑有效温度和混凝土收缩徐变效应后,原型桥和模型桥的有限元分析结果与实测结果吻合较好;原型桥与模型桥在不同施工和成桥阶段的位移和应力相似比不再完全满足7.5和1.0的要求;混凝土收缩徐变预测模型和温度变化历程均会对原型桥与模型桥的位移比例产生较大影响。

Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction sequence and the time-dependent behavior of CABSS,an experimental study of a model bridge was explored.But the measured displacement and stress ratios of arch rib between prototype and model bridge did not subject to linear similarity relation when the time-dependent behavior was considered.So,the three-dimensional finite element models were established,and verified by the measured data.Then,the displacements and stresses of the prototype and model were compared with each other,when the elastic analysis or coupling of temperature and shrinkage,creep effect was considered.Furthermore,a parametric study was studied.The results showed that when the temperature,shrinkage and creep effect of concrete are considered,the finite element analysis results of prototype and model agree well with the measured results.The displacement and stress ratios of prototype and model bridge in construction and bridge completed stage do not present the geometric similarity ratio 7.5 and 1.0,respectively.They are also much influenced by concrete predicting model and variation of temperature.