【作者】 杨俊；

【导师】 杨德灿；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2005， 硕士

【摘要】 斜拉桥合理成桥状态的确定是斜拉桥设计中的关键问题,围绕这一课题,国内外许多研究者发表了不少论文。本文在分析总结前人研究成果的基础上,提出了采用综合最小弯曲能量法和应力平衡法来确定斜拉桥的合理成桥状态,并通过大型通用有限元计算程序ANSYS来实现这一过程。 最小弯曲能量法以结构的弯曲应变能为目标函数,通过求出最小弯曲能量来求得合理索力。运用该方法得到的索力比较均匀,但在求解过程中,人为增大了塔、梁、索的截面积,无法计入预应力的影响,而且忽略了拉索引起的势能,得出的索力在尾索区存在着不合理值。使用该方法只能确定由恒载引起的索力,无法计入活载的影响。应力平衡法以主梁弯矩合理为目标,通过主梁上下缘应力平衡来求得拉索索力。使用该方法,能同时考虑恒载和活载的影响,但同样存在着尾部密索区,某些索力不合理的现象。本文提出的综合方法,以最小弯曲能量法确定的状态为初始状态,它是进行调索的基础,然后根据主梁弯矩合理来进行调索,进而得出合理索力。该方法能充分利用两种方法的优势所在,起到优势互补的作用,得到的索力也比分别使用两种方法更合理。 目前,在进行斜拉桥合理成桥状态设计时,通常都是采用专用桥梁设计程序。本文以大型通用有限元计算程序ANSYS为操作平台,通过建立模型,分别采用最小弯曲能量法、应力平衡法、综合最小弯曲能量法和应力平衡法三种方法,对某桥的合理成桥状态进行了计算,比较了计算结果。分析表明,使用综合法确定斜拉桥的合理成桥状态,同时考虑到了索、梁、塔的受力,所确定的索力状态要优于单一使用某一种方法。大型通用有限元计算程序ANSYS,因其功能强大,操作简单,可开发性强,故能够在确定斜拉桥合理成桥状态时采用,如果进行合理的二次开发,其计算精度是相当可信的。本文首次采用ANSYS程序,对斜拉桥合理成桥状态的三种方法进行了计算,并对所得计算结果进行了比较,证明了综合法的优越性所在。更多还原

【Abstract】 It is a key problem to determine the reasonable cable forces in designing cable-stayed bridges. Surrounding this subject, many researchers in or outside the country have published many theses. On the basis of analyzing and generalizing the former researchers’ achievements, the least bending energy method combined with stress balance method is adopted to determine the reasonable cable forces by using the large-scale general finite element process ANSYS.The least bending energy method takes the bending energy as the objective function, and gets the reasonable cable forces by seeking the least bending energy. The cable forces obtained by using the method are uniform. But in the solving process, the area of towers, girders and cables is magnified artificially. The influence of pre-stress can’t be exerted and the potential energy caused by cable is ignored, so cable forces in dense cable area are unreasonable. Using this method can only determine cable forces caused by dead loads, but can’t by live loads. The stress balance method aims at the girders’ reasonable moment, getting the cable forces by balancing the stress in girder’s upper and lower margin. Using this method can consider the influence caused by dead loads and live loads meanwhile. But cable forces in dense cable area are unreasonable. The synthetic method takes the state determined by least bending energy as its initial state, which is the base to adjust cable forces. Then according to the girders’ reasonable moment, cable forces are adjusted to get the reasonable forces. Using this method can make good use of the two methods, and the cable forces determined by this method are more reasonable than that of the two.Up to date, when designing the reasonable cable forces of cable-stayed bridges, the special bridges design process is adopted. In this article, based on the large-scale finite element process ANSYS, a bridge’s cable forces are calculated by using the least bending energy method, stress balance method and the synthetic method respectively. After comparing the results, it can be shownthat using synthetic method is prior to anyone of the two. The function of the large-scale general finite element process ANSYS is powerful. It can be used conveniently and exploited greatly, so it can be used in determining the reasonable cable forces. If it can be exploited rationally, its calculation accuracy is more credible. In the article, author firstly use large-scale general finite element process ANSYS to calculate rational completion status of cable-stayed bridge with three methods, compare the results and demonstrate the advantages.更多还原