【作者】 李斐然；

【导师】 张哲； 王清湘；

【作者基本信息】 大连理工大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 自锚式斜拉—悬索协作体系桥是在现代自锚式悬索桥和斜拉桥基础上形成的一种新型缆索承重桥梁,具有受力合理、适应性强、工程造价低等优点,已建成一座并有多座在进行方案设计。本文针对自锚式斜拉—悬索协作体系桥在设计中的相关问题进行研究,主要研究内容如下：1、对自锚式斜拉—悬索协作体系桥的几何非线性分析在精确求解中存在的问题和不足展开研究。以C.R.法为基础研究梁单元的刚体转动,分别使用梁单元的形函数法和稳定函数法计算轴向变形以考虑二阶效应的影响,在求解策略上提出了位移缩减法和多次循环法以提高梁单元非线性求解的收敛性；采用求解单元抗力向量的全量法计算轴向受力单元和索单元,指出了索单元求解中可能存在的多解现象,针对这种现象推导了双杆单元法来获取单索问题的良好初值,提出了多初值求解法以防止发散和舍弃伪解,同时在索结构的求解中引入阻尼刚度矩阵以提高非线性分析的鲁棒性；最后通过各单元有代表性的算例验证算法的收敛性和精度,为后续自锚式斜拉—悬索协作体系桥的分析提供保障。2、通过研究确定了自锚式斜拉—悬索协作体系桥恒载状态的设计变量、约束条件和目标函数,其中考虑了荷载因素和非荷载因素对目标函数确定的影响,并通过约束松弛的二次规划算法进行优化求解,给出了基于有限元的总刚度矩阵减少结构重分析的策略,提出了获取自锚式斜拉—悬索协作体系桥恒载状态的两阶段循环法,通过已建成的庄河建设大桥分析验证该方法的有效性。3、针对04公桥规附录F中给出的混凝土徐变系数幂函数表达式,提出了适合于递推法的指数函数表达式,并采用混合算法进行拟合。即首先用遗传模拟退火算法对徐变系数曲线进行初步拟合,估计传统非线性迭代计算中参数的初值,再通过基于Levenberg-Marquardt法和Gauss-Newton法的非线性最小二乘法对徐变系数进行精确的拟合,最后通过结果分析确定了指数函数表达式的最终形式,给出了徐变计算中各系数的取值表。基于此指数函数表达式和按龄期调整的有效弹模法,以力的增量形式推导了徐变的递推表达式,并编制相应的程序分析了新规范中徐变对自锚式斜拉—悬索协作体系桥的影响。4、通过对比几种常见桥型中采用的结合段构造,分析其优缺点,对金州海湾大桥的钢混结合部进行了试设计,提出了考虑材料非线性的多级收敛准则。针对自锚式斜拉—悬索协作体系桥中钢梁与混凝土梁结合部的多种连接方式,应用有限元软件ANSYS,建立了板单元与实体单元相结合的空间有限元模型,考虑了钢构件与混凝土之间的粘结滑移特征,以研究结合段的传力机理、应力分布特点和局部稳定性等问题,通过两种主要荷载工况下的结合部有限元分析,讨论了不同构造下接触面的应力分布、剪力连接器的内力状况、钢梁的剪力滞效应,得到了结合段的多级稳定系数,给出了提高结合部稳定系数的途径,为设计和评价自锚式斜拉—悬索协作体系桥钢混结合段的性能提供依据。5、对自锚式斜拉—悬索协作体系桥在结构设计中计算效率不高的问题进行研究。首先回顾了桥梁设计的发展演变过程,简单介绍了现代设计方法,提出将现代设计方法融入到桥梁设计中,主要体现在利用协同设计综合其他现代设计方法进行结构分析,对目前应用于桥梁分析的软件进行功能划分,研究自锚式斜拉—悬索协作体系桥的协同方法；讨论自锚式斜拉—悬索协作体系桥的结构描述方法,引入并行计算提高结构分析效率,使用Tcl/Tk开发桥梁分析的图形显示模块,实现了基于协同分析的软件系统开发,初步实现了现代设计方法在自锚式斜拉—悬索协作体系桥设计中的应用。更多还原

【Abstract】 The self-anchored cable-stayed-suspension bridge is a new type of cable supported bridges, originating from modern self-anchored suspension bridges and cable-stayed bridges. It takes a lot of advantages, i.e. reasonable mechanical behaviors, strong foundation adaptability, saving cost. One of this bridge type was accomplished and several other bridges were in scheme design. In this paper, some problems about the bridge design are studied. The main research work covers the following aspects:1. Problems and shortages about accurate solution of geometric nonlinear analysis in self-anchored cable-stayed-suspension bridges are studied. C.R. method is used to study the rigid body rotation of beam element. The axial deformation is calculated by shape function and stability function method to take second-order effects into account. A displacement reduction and multi-cycle method are proposed to improve the nonlinear solution convergence of beam element. The element resistance vectors of axial and cable elements are calculated by total lagrange method. The cable element may exists multiple solutions is put forward. In order to solve the problem, a double bars element method is derived to obtain a good initial value and a multi-initial values method is proposed to prevent divergence and abandon spurious results. Meanwhile, a damping stiffness matrix is introduced in the cable element solution to improve the nonlinear analysis robustness. The elements are verified by the representation examples to prove the convergence and precision, which offer guarantee for the further analysis of self-anchored cable-stayed-suspension bridges.2. The permanent load state is investigated for the self-anchored cable-stayed-suspension bridge. Design variables, constraint conditions and objective functions are then determined, where the load and non-load factors are considered. A quadratic programming method for constraint relaxation is used to solve the optimization problem, and a method about how to reduce structure reanalysis by the global stiffness matrix is presented to improve the solution speed. Finally, a two stage cycle method is proposed to obtain the permanent load state of self-anchored cable-stayed-suspension bridges, and Zhuanghe Jianshe Bridge is studied to verify the effectiveness.3. A hybrid algorithm is adopted to fit the creep coefficient power function introduced in China standard of 2004 highway PC bridge appendix F into exponential function, from which can obtain the successive expression of the creep. The curve of creep coefficient is firstly fitted by the genetic simulated annealing algorithm to estimate the initial data, and then based on the Levenberg-Marquardt method and Gauss-Newton method, the curve is exactly fitted by the nonlinear least square method. The exponential function is determined by the result analysis at last. Based on the exponential function and age-adjusted effective modulus method, the successive expression of the creep is derived. According to the corresponding program, the influences of creep to a self-anchored cable-stayed-suspension bridge are analyzed.4. Compared with several steel-concrete joints of usual bridge type, the advantages and disadvantages are analyzed and the steel-concrete joint of Jinzhou Bay Bridge is trial designed. A multi-convergence criterion is proposed by material nonlinearity. In order to analyze the connection modes of steel-concrete joints, a space finite element model that contains solid elements and shell elements is built by ANSYS. The bond-slip behavior of steel and concrete is taken into account, which aims to study the problems of transfer mechanism, stress distribution, local stability and so on. Finally, the joint is analyzed by two main load cases and the stress distribution of contact surface, internal force of shear connectors and shear-lag effect of steel girder are discussed, from which the multi-stability coefficient of joint are obtained. Ways to increase stability coefficients are also put forward. The method can be applied to design and estimate the steel-concrete joint performance of self-anchored cable-stayed-suspension bridges.5. The problem about low computational efficiency during the structural design of self-anchored cable-stayed-suspension bridges is studied. The development and evolution of bridge design process is reviewed and the modern design methods are introduced. In order to take modern design methods into bridge engineering, the cooperative design method is used to integrate other modern design methods to bridges design. The bridge analysis softwares are divided by functions and the cooperation method is studied. The structure description way is discussed and parallel computation is inducted to improve the analysis efficiency. Tcl/Tk is used to develop the graphic display module. Based on cooperative analysis, the software system is realized and the frame rudiment of self-anchored cable-stayed-suspension bridges is established by modern design methods.更多还原