【作者】 李孟然；

【导师】 高荣雄；

【作者基本信息】 华中科技大学 ， 桥梁与隧道工程， 2006， 硕士

【摘要】 随着国民经济的快速发展和交通量的日益增长,大跨桥梁的修建规模和数量与日俱增,斜拉桥是大跨径及特大跨径桥型中具有很强竞争力的一种桥型。斜拉桥成桥内力分布是衡量设计优劣的重要标准之一,而成桥内力在很大程度上由斜拉索索力决定,因此进行斜拉索索力优化是本文研究的主要内容。目前,索力优化的方法多种多样,可归结为指定受力状态的索力优化,无约束条件的索力优化和有约束条件的索力优化,如刚性支承连续梁法、最小弯曲能量法、力平衡法、拉索用量最小法和影响矩阵法,实际应用中应根据实际情况选择合适的优化方法。混合梁斜拉桥的主梁沿长度方向由两种不同的材料组成,主跨跨越能力大。根据混合梁斜拉桥自身的特点,提出以斜拉桥索塔和梁的最大变位最小为目标,以拉索容许应力为约束条件,建立成桥索力优化模型,同时考虑了主梁钢混接合处的弯矩约束。基于提出的模型,将复合形法应用于索力优化中。另外,重点介绍了单纯形法和复合形法的基本思想、算法过程、适用范围,比较详细地阐述了影响矩阵的求解步骤。本文以无锡市蓉湖大桥为工程背景,应用有限元程序ANSYS建立空间模型,并运用ANSYS自带的优化分析模块进行索力优化分析。详细介绍了ANSYS优化设计技术的基本原理、基本概念,以及优化分析流程,比较了零阶优化分析方法和一阶优化分析方法的优缺点。先用零阶方法初步求得最优索力,然后再采用梯度寻优的一阶方法在最优索力的位置进行更精确的确定。最后,介绍了APDL参数化设计语言的功能,并基于此语言编写了复合形法的实现程序,运用该程序进行蓉湖大桥索力优化分析,得出成桥恒载最优索力。通过比较一阶分析方法和复合形法的优化结果可以得出:采用复合形法进行混合梁斜拉桥索力优化计算,不需求解位移函数的导数,操作起来相对简单,优化结果可行。更多还原

【Abstract】 With the rapid development of the national economy and the increasingly rise of the traffic, the scale and number of bridges with long span increase daily. The cable-stayed bridge is a competitive bridge type of bridges with long span and super span bridges. The distributing of internal force of the cable-stayed bridge at completion stage is one of the important standards to evaluate the design quality. As for bridges at completion stage, the distributing of internal force is determined by the cable tension to a great degree. So it is the main purpose of this paper to study the optimization of cable tension.At the present time, there are various methods to optimize the cable tension. They can be sorted into optimization of cable tension with specified stress state、unconstrained optimization of cable tension and constrained optimization of cable tension. For instance, there are rigid support continuous beam method、minimal bending energy method、force balance method、minimal cable usage method and influence matrix method. In the practical applications, you should select the appropriate optimization method according to the fact.The girder of the hybrid cable-stayed bridge is composed of two materials along the length direction. The main span has large span ability. Based on the characteristics of the hybrid cable-stayed bridge, this paper brings forward an optimization model of cable tension at completion stage. It aims to minimize the maximum displacements of the girder and the main pylon of hybrid cable-stayed bridge. And it takes allowable stress of cable as a restriction. Otherwise, it also considers the restriction of joint bending moment between steel gilder and concrete girder. On the basis of the above model, the paper applies complex method to optimization of cable tension. In addition, the basic idea、arithmetic along with scope of application of simplex method and complex method are stressed. The solving steps of influence matrix are introduced in detail.Based on the Ronghu Bridge of Wuxi city, this paper uses finite element program ANSYS to establish the spatial model, and optimizes the cable tension by optimal analysis module with ANSYS. In addition to particular introduction of the ANSYS optimal analysis technique’s fundamental、basic concepts and optimal analysis flow, the paper also compares the merits and flaws of zero order and first order optimal analysis method. At first, use zero order method to primarily get the optimal cable tension. Then, adopt first order method with gradient optimization to exactly confirm it.Finally, the paper introduces the functions of APDL parameter design language and writes program in this language to carry out the complex method. In this paper, use the program mentioned above to do the optimization of cable tension analysis of RongHu Bridge and educe the optimal cable tension under dead loads and completion stage. By comparing the results of first order analysis method and complex method, we can draw a conclusion as follows: when optimizing the cable tension of hybrid cable-stayed bridge with complex method, there is no use to obtain the differential coefficient of displacement function, so the operation is relatively simple, nevertheless the optimization result is feasible.更多还原