多拱肋蝶形拱桥的施工索力优化研究

Study on Optimization of Construction Cable Forces for Multi-rib Butterfly-shaped Arch Bridges

多拱肋蝶形拱桥由于各拱肋的异化导致结构的受力异常复杂且空间效应明显,针对该桥型索力优化问题的特点,并考虑施工过程中混凝土的收缩徐变和结构的几何非线性等因素的影响,采用割线迭代法进行施工索力的调值计算,并对4种不同的调索方案从钢管内核心混凝土的拉应力、索力的不均匀程度、拱顶位移等方面进行对比分析。结果表明:割线法迭代速度较快,但适用范围小;调索顺序对各关心量值的影响较大,调索顺序不合理甚至会导致构件的破坏而影响结构在施工阶段的安全性及成桥阶段的承载能力;钢管内核心混凝土在索力调整过程中容易受拉开裂,在确定蝶形拱桥的调索顺序时,可将拱脚截面混凝土拉应力的变化规律作为切入点初拟调索方案,再从多个角度判断该方案的可行性。

Due to the alienation of arch ribs of butterfly-shaped arch bridge,the structural behavior of the bridge is particularly complicated and presents obvious spatial effects.According to the characteristic of cable force optimization,the cable forces during the construction stage were calculated by secant iterative method considering the influencing factors such as the shrinkage and creep of concrete and geometric nonlinearity of the structure.In addition,the results of four proposals with different adjusting orders were contrasted from the aspects of tensile stress of kernel concrete in steel tubes,inhomogeneity of cable forces,displacement of vault and so on.The results show that（1） the computational efficiency is improved by the secant iterative method,however,the scope of its applicability is limited;（2） the critical values are quite different for different proposals of cable adjusting order,and some components are even damaged to weaken the security during the construction stage and the bearing capacity on the finished-stage as a result of an unreasonable adjusting order;（3）the tension crack of kernel concrete in steel tubes is easy to occur during the adjustment of cable forces,in order for the adjusting order to be reasonable,the variation law of tensile stress of concrete at the impost of arch can be used as the starting point of cable force optimization,and a preliminary proposal can be worked out,then this proposal can be tested from various aspects.