多塔斜拉桥的结构体系研究

Study on structural system of multi-pylon cable-stayed bridge

多塔斜拉桥由于没有背索将其中间塔锚固到固定点,在活载作用下多塔斜拉桥的塔顶将产生过大的水平位移并导致主梁过大变位。如何确保结构的整体刚度是多塔斜拉桥设计中的关键环节。本文分析了多塔斜拉桥的结构体系,通过对不同结构体系的三塔及四塔斜拉桥模型的数值分析及比较,研究了结构体系对多塔斜拉桥力学行为的影响。结果显示,多塔斜拉桥理想的结构体系是能保证结构具有足够的整体刚度,并使混凝土收缩徐变及温度变化等因素在结构中不致产生过大次内力的体系。同时给出了有益于设计中选择多塔斜拉桥结构体系的结论和建议。

The intermediate pylons of multi-pylon cable-stayed bridges cannot be anchored to fixed points by backstays,indicating that it is possible to cause greater horizontal displacements in the top of towers under the action of external loads. Therefore,it is important to obtain adequate structural stiffness in the design of multi-pylon cable-stayed bridges. In this paper,the structural systems of multi-pylon cable-stayed bridges were investigated. The effect of structural system on mechanical behavior of multi-pylon cable-stayed bridges was analyzed by using a three-pylon cable-stayed bridge and a four-pylon cable-stayed bridge model. The deflection and internal force of models for different structural systems were compared. The results indicated that the best structural system of multi-pylon cable-stayed bridges was the system that had enough structural stiffness and less secondary internal force resulted from concrete shrinkage,creep and temperature effect. Recommendations were given for determining structural system in the design of multi-pylon cable-stayed bridges.