【作者】 金波；

【导师】 李鸿琦；

【作者基本信息】 天津大学 ， 固体力学， 2004， 硕士

【摘要】 本文分别通过数值计算和现场检测两种手段对 DH 立交桥破坏最严重的匝 2西连续梁段进行了承载力分析，并总结出了适于异形连续梁承载力测试的有限元模型和实验方法。结果表明，两种方法所得到的结果比较吻合。 本文还研究了利用数字图像处理技术采集与测量土木结构面内位移的光学测试方法，即形心搜索法。所谓形心搜索法是，在待测面内位移的物体表面均匀喷上浅色背景，然后画上数个与背景颜色反差很大的离散标记，最后利用变形前图像和变形后图像当中相对应的标记形心坐标的变化作为该标记形心处的位移增量来测量梁体表面位移的方法。在提取标记形心处的位移增量时，用计算机图形学、边缘检测、图像二值化等数字图像相关知识处理图像得到了数据，并开发了数字图像数据处理系统。利用这一系统，可以准确地获得标记形心处的位移。从实验数据表明，此方法的误差一般在 0.1—1%之间，绝对误差绝大部分都在10 μm以内，也说明了此方法是计算速度快、精度高的测量方法。 本文将形心搜索法和有限元法位移插值函数相结合探索了快速测量桥梁梁体局部表面位移场、应变场的一种新方法。所用测量节点位移增量的方法是形心搜索法，并用插值函数设定了单元内的位移模式，并在此基础上进一步求出了单元内的应变和应力。较一般方法测物体表面局部位移场、应变场，具有较高的精度和很高的计算速度。在本文中，在待测位移场的梁体表面上喷上以矩阵形式排列的m×n个与背景颜色反差很大的离散标记，以标记形心坐标作为变形前节点坐标，以变形前图像和变形后图像当中相对应的标记形心坐标的变化作为节点位移增量，用弹性力学平面问题理论进一步计算出了单元内的应变和应力。 本文还在数字图像相关原理的基础上，把形心搜索法与数字图像相关方法进行了结合。在数字图像相关测量方法的相关算法中，每一种算法都需要获取初始值，而且初始值的获取对于相关运算的正确性和计算速度起着至关重要的作用。本文的计算方法以用形心搜索法得到的标记形心处的位移增量作为初始值，并以变形前标记形心处的坐标值作为子区中心值，并运用相关理论计算了包含一个标记的变形前后图像。从而节省了初始值的搜索所用的时间，并保证了相关运算收敛于全局最小值点。更多还原

【Abstract】 In recent years, the highway construction of our country has gotten the hugeachievement that makes one focus attention with the fast development of nationaleconomy. Highway nets extending in all directions of many cities that take higherlevel highway as main skeleton have already formed preliminarily. But after bridge isestablished and open to traffic, various factor can make safe degree of bridge dropalong with time pass.Now only from increasing of vehicle load and traffic, many bridges have huge hiddentrouble. So, in order to guarantee the safe operation of existing bridge and prolong itssafe tenure of being used as far as possible, it is necessary to detect and assess existingbridge and to know its safe condition and surplus bearing capacity. Therefore, for builtbridge recently and old bridge, detection to bridge has very important meaning. This paper has analyzed bearing capacity to continuous beam section damagedseriously of DONG-HUAN overpass by numerical calculation and detection on jobsite respectively and has summarized experiment method and finite element modelthat are suitable for test of bearing capacity of irregular continuous beam. As a result,the conclusions gotten by two methods are coincident fairly. This paper has still studied the method of handling the displacement in structuralsurface using digital image-center of figure search method. The center of figure searchmethod claimed is the method that spray the background of light color on surfacemeasured, then draw the great marks that their color is different from the backgroundcolor, finally take the change of coordinates of some corresponding center of figure inoriginal image and formed image as displacements of the center of figure. When drawing the displacement increment of marked center of figure, this paperhas handled images by computer graphics and edge detection etc, and developeddigital image processing system. Using this system can get the displacement ofmarked center of figure accurately. From experimental datas, the error of this methodis in 0.1 — 1% generally and absolute error is nearly in 10 μmwithin. It is a methodwith rapid calculating speed and high precision. This paper has established an rapid and effective calculation method of measuringstrain value of marked center of figure at the foundation of analyzing digital imagecorrelation principle fully.<WP=5>In digital image correlation method, to obtain initial value play a most important rolefor the correctness and speed of correlation operation. The calculation method of thispaper takes the displacement increment of marked center of figure as initial value andtakes coordinates of marked center of figure in original image as center values ofsubset, to calculate original and formed image including a mark by correlation theory.So, can raise calculation speed and precision under the prerequisite of guaranteeingcorrelation operation to restraint the minimum value point of overall points.更多还原