Detection Of Bridge And Optical Detection Exploring Method

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.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.