Study on the Optimization of Construction Cable Tensions for Multi-rib Butterfly-shape Arch Bridges

Abstract

Due to the alienation of arch ribs on a butterfly-shaped arch bridge, the structural behavior of the bridge is particularly complicated and presents obvious spatial effects. The cable forces during construction are calculated by the secant iterative method considering factors, such as the shrinkage and creep of concrete and geometric non-linearity of the structure. In addition, the results of four proposals with different cable-adjusting orders are compared based on the angles of tensile stress of kernel concrete in the steel tubes, inhomogeneity of cable forces, and the displacement of the apex of arch, and so on. Based on the results, the computational efficiency is improved by the secant iterative method, however, the scope of its applicability is limited. The critical values are quite different for different proposals, and some components even become damaged, such that they weaken the security during construction and the bearing capacity during the finished stage as a result of an unreasonable cable-adjusting order. To render a cable-adjusting order reasonable, the variation law of tensile stress of concrete at the impost of the arch can be used as the starting point of optimization of cable tensions. A preliminary proposal can then be worked out, and this proposal is tested from various angles.