循环温度对大跨混凝土拱桥长期变形行为的影响

为探讨自然环境条件下高速铁路大跨度劲性骨架混凝土拱桥在运营阶段拱顶截面位移和应力的时变特征,以沪昆客运专线北盘江大桥(主跨445m的钢筋混凝土拱桥)为背景,采用MIDAS Civil软件建立全桥有限元模型,结合成桥后的位移测试结果,分析了循环温度与收缩徐变耦合效应对其长期变形行为的影响。结果表明:年循环温度引起的拱顶截面竖向位移远大于1年内的收缩徐变变形,不同成桥季节对拱圈变形有一定影响,该循环温度效应不容忽视;当考虑温度与收缩徐变耦合效应时,拱顶截面钢管应力可达到屈服强度,外包混凝土应力有较大波动;建议进行混凝土拱桥长期变形效应分析时,应考虑温度和收缩徐变耦合效应。

Effects of Cyclic Temperature on Time-Dependent Deformation Behavior of Long-Span Concrete Arch Bridge

To study the time-dependent deformation and stress in the arch crown of a long-span arch bridge, which is constructed with stiffened skeleton concrete, on high-speed railway under natural environment in service stage, the Beipanjiang Bridge (a reinforced concrete arch bridge with the main span of 445 m) in the Shanghai-Kunming passenger dedicated line was selected as an engineering background. The whole bridge was simulated by the finite element program MIDAS Civil. Based on the measured vertical displacement results after the bridge being completed, the influences of a coupling effect of cyclic temperature, shrinkage, and creep on the time-dependent behavior of arch were analyzed. The results demonstrate that the vertical displacement of arch crown caused by annual cyclic temperature is much greater than that caused by concrete shrinkage and creep in one year. The deformation of the arch can be influenced by the bridge constructed in different seasons, and the cyclic temperature effect should not be ignored. The stresses of steel tube in arch crown can reach the yield stress, and the stresses of surrounding concrete will fluctuate with time when the coupling effect of cyclic temperature, concrete shrinkage and creep are taken into account. It is suggested that the coupling effect of cyclic temperature and shrinkage and creep should be emphasized when analyzing the time-dependent behavior of the concrete arch bridge.