异形拱桥结构设计及空间受力分析

摘要

This paper takes the tied-arch bridge of Zhongxing Road Beiyan New Cross-Qinhuai River of Nanjing City as the subject to study the static spatial effect and dynamical properties of irregular-shape arch bridge broader box girder.A model for the upper space girder of this bridge is built by using MIDAS/Civil and grillage method.Based on this model the stress distributions of typical sections are obtained in both transient situation and persistent situation.Then subspace iteration method is employed to investigate the structural mode of the completed bridge state.The results show that tension stresses in cross beams are large under transient situation and the compression in concrete girders is large under persistent situation.The whole cross-sections of girders are always in the state of pressure and the distribution of stresses makes the spatial effect of the structure more remarkable.Moreover the preliminary beam theory is not applicable any more.The stiffness of arch rib is smaller compared with that of girders for the deformation of girder appears firstly in the 46th modal.%为研究异型拱桥宽箱梁结构的静力空间效应和动力特性，以南京市中兴路北延跨秦淮新河下承式系杆拱桥为研究对象，基于MIDAS／Civil软件建立该桥上部结构空间梁格模型，分析短暂状态和持久状态结构主梁典型截面的应力分布。采用子空间迭代法探讨成桥状态结构模态。结果表明：短暂状态横隔梁的拉应力较大，持久状况下主桥混凝土梁段压应力较大。主梁截面应力在全过程均为全截面受压，且应力分布凸显了结构的空间效应，初等梁理论不再适用。主桥上部拱肋与主梁相比刚度较小，主梁竖弯初见于第46阶模态。