大跨度拱桥吊装过程计算方法

Research on computation methods for long-span arch bridge in constructing process while its precast segments are assembled with cables

研究了缆索吊装施工的大跨度拱桥吊装过程计算方法。施工实践中拱圈预制节段存在一次放松吊钩和逐步放松吊钩并张拉扣索2种不同的安装就位方式,其对预制节段安装位置的要求有所不同,而现有的计算方法未对这2种就位方式加以区分,为此,提出了一次放松吊钩时的正装迭代法和逐步放松吊钩并同时张拉扣索时的刚性支承-弹性索法,并研究了它们的实施细节。采用这2种方法均可以直接求出拱圈预制节段安装过程中节段安装位置和扣索索力。运用所提出的方法对一个工程实例进行了分析。计算结果表明,采用不同的方法就位时对安装位置的要求差别很大,但对扣索索力影响不大。

The computation methods were studied for long- span arch bridge in constructing process while its precast segments are lifted and assembled with cables. There are two methods in practical construction to make the segments installed at the desired position while assembling them with cables. One of them is to unfasten the lifting cables in a lump without tension the buckling cables, and the other is to unfasten the lifting cables step by step and at the same moment tension the buckling cables. The existing methods presented in most papers didn＇t consider the different demand of installation position for each segment. This paper suggested two methods for computing proper installing posi- tion and forces of the buckling cables. One is iterative forward - analysis method, which is applicable to the situation of unfastening the lifting cables without tensioning the buckling cables, and the the other is rigid - supporting - to - e- lasticity - cable method, which is applicable to the situation that the lifting cables are unfastened step by step with the buckling cables tensioned. Details of the two methods were discussed. Cable forces and the installation position of every segment during the construction process can all be conveniently obtained. At the end, a practical example computed in these two methods was given. The results indicate that when the precast arch segments are installed in different adjusting methods, the installing position is dramatically influenced while there is minor influence to forces of the buckling cables.