【作者】 刘兆丰；

【导师】 赵人达；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 随着交通量的增加,桥梁设计得越来越宽,一种新颖的桥梁断面形式——双幅桥面桥梁以其宽敞的视觉效果、良好的行车条件而逐渐受到人们的青睐,双幅桥面桥梁在国内外的建设也在逐渐增多。大多数的双幅桥面桥梁是两座平行独立的桥梁,除气动干扰效应外受力完全独立,正在建设中的宁波甬江特大桥除具备双幅桥面桥梁的特点外,将两幅桥的索塔横向联成整体,两幅桥的受力通过联塔部位相互传递,呈现出耦合状态,联塔结构本身的工作状态和安全储备受到工程师们的瞩目。本文在收集国内外相关资料和深入分析已有研究成果的基础上,以宁波甬江特大桥为背景,研究联塔分幅斜拉桥的结构行为,并对联塔结构进行模型试验研究。主要研究内容如下：1.详细推导了随施工阶段变化的结构状态量对斜拉索施工张拉力以及预拱度的响应函数关系式,并考虑几何非线性和徐变的影响。依据这些响应函数,针对斜拉桥悬臂浇筑施工过程中斜拉索施工张拉力的优化,建立了数学规划模型,利用多目标、多约束优化算法编制了相应的MATLAB程序进行斜拉索施工张拉力的优化。基于ANSYS中的APDL语言编制了斜拉桥悬臂浇注施工阶段分析的程序,以实现施工仿真分析的程序化、简单化。在仿真分析中,对斜拉桥在施工及成桥阶段的线性和非线性效应作了简要比较。2.鉴于两幅桥梁受力的耦合性,对两幅桥梁的受力相互影响程度进行了定量分析。拓展联塔部位的刚度参数、联结区域长度,考察两幅桥梁相互影响对这些参数的敏感性。3.鉴于我国规范规定的气动三分力系数和风荷载计算是仅针对单幅桥面桥梁,利用有限元程序ANSYS中的FLOTRAN CAD模块对甬江特大桥双幅桥面桥梁的风力三分力系数进行了数值模拟研究。并对联塔分幅式斜拉桥、分离塔单幅式斜拉桥两种塔结构型式的斜拉桥的静风稳定性能及动力特性进行了比较分析。4.以宁波甬江特大桥为工程背景,对其整个联塔结构进行室内模型试验研究。针对模型试验中加载斜拉索的布置位置、数量及索力的确定,提出了最少索数的索力优化方法,编制了相应的数值分析程序。在满足目标状态要求的前提下,以最少斜拉索数量为原则确定了试验中斜拉索的优化布置及相应的优化索力,在达到预期目标的同时增加了斜拉索的利用率,且减少了资源的耗费。5.模型试验对联塔结构的受力性能进行了研究,测试了联塔结构的变形、控制断面的应力、斜拉索索力,实测值与计算值符合较好。通过试验验证了最少索数优化方法的合理性和可行性；明确了各斜拉索特别是不同塔上斜拉索之间的索力相互影响程度；验证了联塔结构在施工、运营阶段的受力性能；对联塔结构模型进行了极限承载力测试,结果表明结构有较大的安全贮备。本研究表明：大跨宽幅斜拉桥中采用联塔分幅结构型式是可行的。更多还原

【Abstract】 With the increase of traffic volume, bridges are designed with more and more wide decks, a kind of novel twin-deck bridge emerges as the times require. With spacious visual effect and good driving conditions, the twin-deck bridge gradually wins many people’s good graces. The number of twin-deck bridges built at home and abroad gradually increases day by day. Most twin-deck bridges are two parallel structures, which are in independent force state except for aerodynamic interference effects. Yongjiang super-large bridge being built in Ningbo is a twin-deck cable-stayed one, but twin pylons of separate twin-decks are transversely joined into a monolithic one. The forcing states in twin bridges are mutually transferred through the joint part of the pylon. Twin bridges are in coupling force state. The working state and the safe reserve of the united twin-pylons have attracted engineers’attention. On the basis of collecting and studying correlative information at home and abroad, taking Yongjiang super-large bridge as an example, the structural behavior of cable-stayed bridges with separate twin-decks and united twin-pylons is studied and model test study on the united twin-pylons is made. The main research work is as follows:1. The structure state variables change with the construction stages going on, The variables can be expressed as the functions of cable forces and construction camber. The functions are derived in detail by considering the effect of geometric nonlinearity and creep. On the basis of the functions, a mathematical programming model for cable forces optimization in the cantilever construction stages of cable-stayed bridges is established, and the optimization program method is developed by the multi-objective, multi-restriction optimization algorithm using MATLAB program language. The command file about the simulation analysis for the cantilever construction stages of cable-stayed bridges is programmed on the basis of the development tool APDL language in ANSYS, which makes simulation analysis with a rule and simple. The linear and nonlinear calculation results are simply compared in the construction stages and the finished stage.2. In view of the coupling force state of twin bridges, quantitative analysis of the interaction degree of their force state is performed. A series of parameters extension analysis is carried out with different stiffness of the joint part and different lengths of the joint zone in order to study the parameters’effects on the interaction degree of twin bridges.3. Whereas aerostatic coefficients and wind loads specified in domestic codes are only in view of bridges with one deck,the aerostatic coefficients of two separate decks in Yongjiang super-large bridge are numerically simulated using the FLOTRAN CAD module in ANSYS. The stability in static wind and dynamic characteristics between the cable-stayed bridge with separate twin-decks and united twin-pylons and the one with single deck alone are compared.4. Taking the Yongjiang super-large bridge in Ningbo as an example, model test study on united twin-pylons is done. In order to optimally determine the assigning positions of stayed-cables, the number of stayed-cables and cable forces in the test, mathematical model and numerical programs for the least cables are developed. On the premise of meeting target state, assigning positions and corresponding cable forces are optimally determined according to the principle of minimal number of stayed-cables. Thus, at the same time of achieving the desired goal, the rate of utilization of stayed-cables is increased and the resource cost is reduced.5. Structural behaviors of united twin-pylons are studied in the model test. Displacements, stresses in control sections and cable forces are measured. The measured and the calculated results agree well. The rationality and feasibility of the cable forces optimization method for the minimal number of stayed-cables is verified by the test results. The mutual influence among stayed-cables, especially among those between different pylons in the united twin-pylons are made clear. Structural behaviors of united twin-pylons in the construction stages and the finished stage are shown in the test. Finally, the ultimate bearing capacity is tested and it shows a high coefficient of safety for the united twin-pylons. The model test results show that the cable-stayed. bridge with twin-united pylons and twin separate girders is feasible.更多还原