矮塔斜拉桥近似分析方法研究

发布时间：2018-03-07 21:08

  本文选题：矮塔斜拉桥　切入点：索梁活载比　出处：《长安大学》2016年博士论文　论文类型：学位论文

【摘要】：矮塔斜拉桥作为一种具有竞争力的组合桥型,该桥型的力学性能介于连续体系梁桥和常规斜拉桥之间,具有良好的经济性能和美学效果。开展矮塔斜拉桥结构体系方面的研究具有重要的现实意义。本文从结构分析角度分析了矮塔斜拉桥中设计理论中存在问题,所做的主要研究工作和取得研究成果有:(1)文中首先简要介绍了矮塔斜拉的起源及发展现状,指出索梁活载比可在本质上反映矮塔斜拉桥在车道荷载作用下的结构效应。本文采用比拟梁法,推导了车道荷载作用下的单塔、双塔及多塔矮塔斜拉桥的索梁活载比计算公式。研究了索梁活载比与结构参数之间关系,进一步指出索梁活载比可从力学本质上反映了矮塔斜拉桥索梁塔及支承条件等结构特性,以此可方便设计人员从宏观上把握矮塔斜拉桥的结构性能,在概念设计阶段选择合理的结构参数。(2)基于荷载平衡理论、索膜理论推导了恒载作用下的主梁的弯矩、轴力及主塔的轴力;基于弹性支承连续梁理论推导了活载作用下的主梁、主塔的弯矩和挠度;在推导主梁的竖向位移计算表达式时,本文考虑了拉索的弹性变形、主塔的偏位及弹性压缩变形等因素(3)为方便计算矮塔斜拉桥的自振频率,分别基于双塔塔梁固结、墩支承的矮塔斜拉桥和高墩固结体系矮塔斜拉桥,应用Rayleigh法,推导了其一阶对称和反对称竖弯振动频率公式及纵向漂浮基频估算公式,并提出了名义单位质量的抗弯刚度的概念,最后对此公式的可行性进行了算例验证,并讨论了该公式的应用对象。研究结果表明:支承条件对矮塔斜拉体系的基频影响较大,进行频率计算时应准确考虑支承条件;给出的能量法得到的基频计算值与有限元值误差能满足概念设计阶段的要求;该公式适用于双塔塔梁固结、墩支承的矮塔斜拉结构和高墩固结体系矮塔斜拉桥,并指出抗风设计规范中的竖弯基频公式不适用于双塔塔梁固结、墩支承的矮塔斜拉结构。(4)为研究多塔矮塔斜拉桥的中塔纵向刚度,将拉索对桥塔的约束等效为弹簧单元。在推导中采用能量守恒原理,忽略了主塔的弹性压缩。在活载作用下桥塔发生纵向变形,并引起主塔的纵向弯曲、主梁的竖向弯曲及拉索弹性伸长,在此过程中拉索的水平向做功等于主梁的重力势能增量与斜拉索的弹性势能增量之和,据此推导出了拉索对中塔纵向约束刚度表达式。研究表明:等效弹簧刚度与斜拉索线刚度成线性关系;与斜拉索水平角存在一定关系,并不与等效弹簧刚度成线性关系;此公式具有较高的计算精度,可供概念设计阶段选取合理的结构参数使用。(5)为研究多塔矮塔斜拉体系的在活载作用下的主梁的竖向挠度,将斜拉体系等效为多跨弹性支承连续梁。基于多塔斜拉体系的结构力学本质,推导了单位荷载作用下的边中跨拉索弹性支承刚度系数的计算表达式。并对其进行了参数研究,最后对斜拉体系的塔梁刚度进行讨论。(6)针对预应力混凝土矮塔斜拉桥的特点,提出了基于索梁权矩阵的索力优化方法。该方法的思路是以主梁截面上下缘的正应力为控制条件,给出主梁截面恒载应力可行域和弯矩可行域,即将《公路桥规》中规定的设计强度值减去活载作用在主梁截面活载应力包络值,使其落在主梁截面应力可行域内;并提出单位荷载法,采用最小二乘法原理,以索梁权矩阵为优化目标,来解决优化索力和预应力优化配置问题,使主梁上下缘的正应力位于上述可行域内。采用编程实现了这一方法并进行了实桥算例验证(7)收集国内外连续体系梁桥、常规斜拉桥及矮塔斜拉桥的资料,统计了混凝土、普通钢筋及拉索(或预应力筋)用量指标,以此拟合上述三种桥型的经济跨径;从结构体系措施、构件措施及材料措施等角度分析指出,改善大跨度矮塔斜拉桥力学性能的措施;最后根据本文所推导的近似估算公式,从力学性能角度分析了矮塔斜拉桥极限跨径。论文对推导的近似计算式,均获得了有限元解的验证。
[Abstract]:As a competitive bridge low tower cable-stayed bridge, the mechanical properties of the bridge system between continuous girder bridge and conventional cable-stayed bridge, which has good economic performance and aesthetic effect. It is of great significance to research the extradosed cable-stayed bridge structure system. This paper from the angle of structure analysis the problems of the design theory of the extradosed cable-stayed bridge, the main research work and research achievements are: (1) this paper briefly introduces the origin and development status of Extradosed cable girder, pointed out that in essence the live load ratio reflects the structure effect of extradosed cable-stayed bridge in lane loads the paper used the beam analogy method, deduces the single tower under Lane loads, the Twin Towers and the tower of the extradosed cable-stayed bridge cable beam live load ratio. The calculation formula of cable beam live load ratio and the relationship between structure parameters, further pointed out the cable beam The live load ratio from the mechanical essence of extradosed cable-stayed bridge cable tower and beam condition of supporting structure characteristics, which can be used to facilitate the designers to grasp the structural performance of the extradosed cable-stayed bridge from the macro view, select the reasonable structure parameters in the conceptual design stage. (2) the load balance based on the theory of membrane theory the main beam under the action of dead load bending moment, axial force and axial force of tower; based on the theory of elastic bearing continuous beam girder under live load, the main tower of the bending moment and deflection in vertical displacement is derived; calculation formulas of girder, considering the cable's elastic deformation, deflection and elastic main tower of compression deformation and other factors (3) to facilitate the calculation of the natural frequency of the extradosed cable-stayed bridge, based on the Twin Towers tower pier beam consolidation respectively, supporting the extradosed cable-stayed bridge and high pier consolidation system of extradosed cable-stayed bridge, using the Rayleigh method to deduce the first-order symmetric and anti symmetric 绔栧集鎸�鍔ㄩ�戠巼鍏�寮忓強绾靛悜婕傛诞鍩洪�戜及绠楀叕寮，

本文编号：1580959