【作者】 张群；

【导师】 刘沐宇；

【作者基本信息】 武汉理工大学 ， 桥梁与隧道工程， 2011， 硕士

【摘要】 结合梁斜拉桥因其相对混凝土斜拉桥和钢斜拉桥的跨越能力大,梁高小,外观轻巧,用钢量少,自重小,造价合理,施工简便等优点,近年来在我国的桥梁建设中得到了广泛的应用。正在建设中的武汉二七长江大桥是主梁采用钢结构、桥面板为混凝土结构的世界最大跨径三塔结合梁斜拉桥,为了使大桥建成后受力合理,对三塔结合梁斜拉桥进行施工计算分析,掌握施工阶段桥梁内力特性是十分必要的。目前常用分析方法主要有倒拆法、正装法、正装迭代法等,其中正装迭代法可以根据桥梁实际施工顺序模拟实际施工过程,并且能避免计算结果不闭合问题。本文以武汉二七长江大桥为工程背景,首先系统地分析了结合梁斜拉桥施工过程计算分析的整体思路,并重点分析探讨了结合梁斜拉桥施工过程计算的理论,然后在介绍武汉二七长江大桥主梁施工过程的基础上,基于正装迭代法,运用Midas/Civil软件建立全桥空间有限元分析模型,确定合理的成桥状态和施工状态,得出合理成桥索力以及斜拉索的初张力,系统地计算分析了全桥的施工过程。具体地说,本文主要进行了以下几个方面的工作：1、在现有斜拉桥施工过程分析资料的基础上,总结大跨度结合梁斜拉桥施工方法及计算分析基本理论。目前常采用的倒拆法、正装法、倒拆-正装迭代法、无应力状态法等都或多或少存在这些不闭合的问题,即按这些方法计算得到的控制参数进行正装计算所得成桥状态与设计成桥状态不一致。而正装迭代法只需要进行正装计算,且可以通过差值法将不闭合造成的影响降低到最低程度。2、基于正装迭代法,运用MIDAS/CIVIL有限元分析软件,通过建立三塔结合梁斜拉桥双主梁空间有限元模型,分析其各施工阶段及成桥阶段的内力、位移和索力,经过与合理成桥状态进行对比分析,最终确定各施工阶段的节段标高、索力及主梁内力。计算结果表明：合理施工索力与合理成桥索力相比,误差均在±5%范围内,主梁最大抛高40.3cm,混凝土桥面板未出现拉应力,且最大压应力为8.8Mpa,钢主梁下翼缘最大压应力为159Mpa,说明三塔结合梁斜拉桥施工受力合理,斜拉桥索力、主梁内力和位移均满足设计规范要求3、施工过程中,由于变形、内力不断累积,所以,在悬臂拼装的过程中,最大悬臂状态为最不利状态。在完成某一节段的施工后,后续5-10个节段的施工对该阶段各个参数影响都比较大,因此,必须对后续5-10个阶段的施工给予重视以保证施工过程的安全和成桥状态符合设计要求。更多还原

【Abstract】 The composite cable-stayed bridge is developing quickly in china recently years which have the advance of fewer steel consumption, lower deadweight and reasonable construction cost. The constructing Wuhan Erqi Yangtze river bridge which girder composed by the steel I beam and concrete deck is the largest composite girder cable-stayed bridge with three towers of the world. To ensure the bridge have a reasonable load distribution in finished bridge state, so grasping the internal force of the constructing is quite necessary. The methods carried out to analyze the bridge construction present have forward-calculation method, taking-away method, forward-iteration method and so on, above all, the forward-iteration method can simulate the construction process and could avoid the question of calculation outcome non-closed.This document takes the Wuhan Erqi Yangtze river bridge as background, firstly to make an whole thought of the way to simulate composite girder bridge construction, to discuss the calculation theory of the composite girder bridge constructing, and then based on the forward-iteration method, a FEM analysis modal of the bridge was built in the Midas/Civil program, after calculation, the reasonable finished bridge state and construction state can be get, and the reasonable final cable force can be calculated. The main conclusion of this document as following:(1)Summarize the basic theory of the construction method and simulation of large-span composite bridge;(1)Based on construction process analysis data of existing cable-stayed bridge, Summary the construction method and calculation of the basic theory of large-span composite cable-stayed bridge. Currently often used methods,such as forward method, backward method, forward-backward iteration method and unstressed state method, More or less exsit a not closed problem, that is the state Calculated by these methods of control parameters loaded into the bridge forward-calculation and the state designed to finished bridge state is inconsistent, however, forward iteration method only needs forward-calculation, and it can minimize the impact of not closed by using the differential method.(2) Based on the forward-iteration method,a FEM modal of Wuhan Erqi Yangtze river bridge considering two-girders of the bridge was built in the Midas/Civil program, Analyzing the internal force of bridge, displacement, and cable tension of the various stages of the construction and completed bridge state.comparative analysis reasonable completed bridge state, Ultimately determine Segment elevation, the internal force of main girder,cable tension of each construction stage. The calculation results show that:compared the cable tension of reasonable construction stage to completed bridge state, errors are within±5%.The maximum high throw of main girder is 40.3cm, tensile stress of concrete Bridge deck does not appear,and the maximum compressive stress is 8.8Mpa,the maximum compressive stress of bottom flange of the main steel girder is 159Mpa,which can illustrate the force in construction stage of the composite cable-stayed bridge with three towers is reasonable, the internal force of main girder, tension and displacement meet the design specifications.(3)In the construction process, due to the accumulation of the deformation, internal forces accumulate, the Maximum cantilever state is the most adverse conditions in the process of assembling cantilever. After completed construction of a segment, the construction of following 5-10 segments have a large influence on each parameter of the stage.So,it should give attention to the construction of following 5-10 segments,which can ensure the safety of the construction process and make completed bridge state meet the design specifications.更多还原