自锚式悬索桥吊索张力及主缆线形的设计研究

Design of hanger tension and cable configuration for self-anchored suspension bridges

确定自锚式悬索桥的吊索张力及主缆线形是设计中的难点。由于吊索是在架设完加劲梁和主缆后安装并张拉的,所以吊索张力的大小对自锚式悬索桥的内力状态影响很大。因此,研究提出以主梁弯曲应变能最小为目标的无限轴向刚度法,用它确定吊索的合理张力;考虑吊索张力后的主缆精确线形是分段悬链线,通过迭代计算可求解出主缆线形及内力;依据吊索安装前后主缆及主梁的无应力长度相等的原则,可联立相关方程,求解出吊索安装前主缆在塔顶的预偏量和各索夹在主缆上的定位。

Design of hanger tension and main cable configuration constitutes the key issues in designing self-anchored suspension bridges.Since hangers are installed between the pre-constructed stiffening girder and main cable,their tensions have fundamental influences on the flexural state of the stiffening girder.A infinite-axial-stiffness method is proposed,based on minimizing the flexural strain energy of the stiffening girder,to determine the reasonable hanger tensions.The rigorous cable configuration under hanger tensions is in the form of segmental catenaries.An iterative procedure is developed to solve the cable force and configuration.Thereafter,realizing the fact that the zero-stress length of the main cable and the stiffening girder remain unchanged with or without hangers,relevant equations can be used to find the cable offset position on the tops of towers before installing the hangers,the hanger bands can also be positioned in this construction stage.