【作者】 江锋；

【导师】 叶梅新；

【作者基本信息】 中南大学 ， 桥梁与隧道工程， 2004， 博士

【摘要】 斜拉桥因其强大的跨越能力和优美的景观而得到人们的青睐。随着科学技术的进步和社会需求的增长，斜拉桥数量越来越多，跨度越来越大，结构形式也日益多样化。我国大江大河众多，斜拉桥在中国有着广阔的应用前景。斜拉桥是一种柔性结构体系，实践证明，设计计算中必须考虑几何非线性，如果作承载力分析，还必须考虑材料非线性。方案比选和初步设计中，经常要变更数据，计算工作量巨大，通用软件虽然功能非常强大，但很难在短时间内获得准确的结果。因此，迫切需要一种简单、实用且能满足工程要求的计算方法和软件为设计服务。斜拉桥主梁和主塔大多为薄壁箱梁结构，其受力状态非常复杂，经典梁理论很难正确反映其受力特性。本文对薄壁箱梁和斜拉索的分析理论和计算方法作了较为深入的研究，提出了新的计算理论和方法，并将其应用于斜拉桥非线性分析，主要取得如下创新性成果： 1、在广泛阅读国内外资料文献的基础上，对斜拉桥非线性特性、薄壁箱梁的计算理论和方法以及存在的问题作了较全面、深入的研究，确定以混合变分原理为本文薄壁箱梁单元的理论基础。 2、提出了基于Hellinger-Reissner混合变分原理的两节点空间非线性薄壁箱梁单元，推导了增量形式的几何非线性有限元方程、弹性刚度矩阵、几何刚度矩阵、初应力荷载阵等的计算公式。该单元考虑了薄壁箱梁的轴向变形、双向弯曲变形、剪切变形、约束扭转变形和截面畸变等因素，较全面地反映了箱梁的变形特征；编制了程序，给出了简单算例。结果表明，该单元简单有效正确。 3、提出了塑性削减应力当量荷载法，将上述两节点空间几何非线性薄壁箱梁单元发展到材料非线性问题，推导了适用于薄壁箱梁的弹塑性本构关系，塑性削减应力增量及其当量荷载增量、塑性削减应力及其当量荷载的计算公式，列出了计算步骤和计算方法。该法将塑性引起的结构刚度的削弱转化为当量荷载，简化了计算；编制了程序，给出了简单算例。结果表明，该法的计算理论和方法正确，简单可行。 4、提出了空间悬链线斜拉索单元，该单元严格按照斜拉索的自然几何形状建立；推导了缆索单元刚度矩阵和节点力列阵；给出了两类缆索问题的算法；考虑缆索与主梁相关节点之间的主从关系；编制了程序，给出了简单算例。结果表明，该缆索单元精确地模拟了斜拉索的几何非线性行为，计算结果真实可信。 5、将上述计算理论、计算方法和所编制程序综合起来，应用于两座单索面斜拉桥的非线性分析计算，其中一座为钢一混凝土混合梁斜拉桥，另一座为预应力混凝土斜拉桥，对该桥还作了成桥静载试验，本文分析计算结果与实测值及通用软件的计算结果吻合良好，但本文的计算准备工作量和计算机时远小于通用软件.计算结果还表明，钢斜拉桥的几何非线性效应比混凝土斜拉桥的几何非线性效应更为明显。 实践表明，本文研究既有理论意义，又有实用价值。关键词斜拉桥，薄壁箱梁，混合变分原理，塑性削减应力当量荷载， 悬链线斜拉索更多还原

【Abstract】 Cable-stayed bridges get into good graces of people because of their great spanning capability and beautiful sight. With the development of scientific technology and increasing demands of the society, cable-stayed bridge has great increase in number and span; its structure form is increasingly diversiform. There are numerous rivers in China, which brings cable-stayed bridge a good future in application. As a kind of flexible structure, practice shows that geometry-nonlinear must be taken into account in the design and calculation of cable-stayed bridge. For carrying capability analysis, material nonlinear has to be taken into account, too. In the comparison of schemes and preliminary design, data are changed often, so that the amount of calculation work is huge. Though current software has powerful functions, it is still difficult to get accurate results in a short time. Therefore, there is an urgent need for a set of calculation methods and software for design of cable-stayed bridges, which should be simple, applied and able to meet engineering demands. The main girders and towers of cable-stayed bridges are usually thin-walled box girder structures, which have complex stress state. The classic beam theory has difficulty in reflecting the deformation characteristic of thin-walled box girders accurately. In this thesis, the author made an in-depth study of the analysis theories and calculation methods of thin-walled box girder and cable, put forward new calculation theory and methods, and applied them into the non-linear analysis of cable-stayed bridges. The main innovative achievements are listed in the following:1. On the basis of extensive reading, an in-depth study was made on the non-linear characteristic of cable-stayed bridges, the calculation theories and methods of thin-walled box girders, and the existing problems in the above -mentioned subjects; hybrid variation principle was fixed to be the theoretical basis of the thin-walled beam element of this paper.2. A two-node spatial non-linear thin-walled box girder element isput forward, which is based on Hellinger-Reissner hybrid variation principle. The non-linear FEM (finite element method) equation, elastic rigidity matrix, geometry matrix and pre-stress load column matrix were formulated. In the element, axial deformation, double flexural, shear deformation, restraining torsion warping and section-distortion were all taken into account, which lead to a comprehensive reflection of deformation characteristic of thin-walled box girders. The corresponding program was designed, and some simple examples were given. The results of the examples show that the element is simple, accurate and effective.3. A method named equivalent load of cut-down plastic stress was put forward, which extended the above two-node spatial non-linear thin-walled hybrid beam element to material non-linear field. The plastic constructive equation suited for thin-walled box beam was derived, the increment of plastic cut-down stress and its resultant, the plastic cut-down stress and its resultant were formulated. The calculation steps were listed out. The method simplifies calculation by translates the impairment of structure rigidity, caused by plasticity, into an equivalent load. The corresponding program was designed, and some simple examples were given. The results of the examples show that the theory and the method are correct, simple and applicable.4. A spatial catenary cable element was brought forward, which was built strictly according to the natural geometric shape of cables. The rigidity matrix and node force column matrix of the cable element were formulated; the arithmetic of two kinds of cable problems was given; the master-slave relationship of the relative nodes between cable element and beam element was considered. Corresponding program was designed and some simple examples were given. The results of the examples show that the catenary cable element simulates the geometric non-linear behavior accurately, the results are actual and believable.5. All the above-mentione更多还原