沪昆高铁北盘江特大桥主拱圈施工全过程非线性稳定性评估

为评估沪昆高铁北盘江特大桥主拱圈在施工阶段的非线性稳定性能,运用LSB软件建立主拱圈有限元模型,基于荷载增量法计算了施工全过程的结构非线性稳定系数,考察其随施工过程的变化趋势,并探讨横向风荷载对稳定系数的影响。结果表明:(1)钢管骨架拼装阶段主拱圈非线性稳定系数值为3.4~35.1,最小值3.4发生在拼装与拱顶合龙段相邻的20号吊装节段,钢管骨架合龙时非线性稳定系数为4.5;(2)灌注钢管内混凝土阶段主拱圈非线性稳定系数值为2.6~3.4,最小值2.6发生在灌注下弦外侧钢管内混凝土;(3)浇筑外包混凝土阶段非线性稳定系数值为2.1~4.4,最小值2.1发生在浇筑全断面以外腹板外包混凝土6个工作面的第5段,也是施工全过程主拱圈非线性稳定系数的最小值;(4)非线性稳定系数对横向风荷载的作用并不敏感。

Nonlinear Stability Assessment of Main Arch Ring during the Whole Construction Process of Beipan River Super Major Bridge on Shanghai-Kunming High Speed Railway

In order to assess the main arch ring nonlinear stability during the construction of Beipan River Super Major Bridge on Shanghai-Kunming high speed railway, LSB software is used to establish the finite element model of main arc ring. Based on load increment method, the structural nonlinear stability coefficient during the whole construction process is calculated and the variation tendency of the coefficient in the construction process is assessed. The effect of the transverse wind load on the stability coefficients is also discussed. The results show that:(1) The nonlinear stability coefficient of the main arch ring at the stage of steel tube assembly ranges from 3.4 to 35.1, and the minimum value 3.4 occurs in 20# lifting segment next to the closure segment of vault, while the value of the nonlinear stability coefficient at the stage of steel tube closure is 4.5.(2) The nonlinear stability coefficient of the main arch ring at the stage of pouring concrete into steel tube ranges from 2.6 to 3.4, and the minimum value 2.6 occurs in pouring concrete into outward bottom chord steel tube.(3) The nonlinear stability coefficient of the main arch ring at the stage of pouring encased concrete ranges from 2.1 to 4.4. The minimum value 2.1 occurs in pouring the 5 th encased concrete segment of webs on six working faces beyond the full section of the main arch ring, which is also the minimum value of the nonlinear stability coefficient of the main arch ring in the full construction process.(4) The nonlinear stability coefficient is not sensitive to transverse wind load.