Photoelastic Experiment And Finite Element Analysis For The Joint Structure Between Pier And Girder In Continuous Rigid-Frame Bridge

The prestressed concrete continuous rigid-frame bridge, which based onprestressed concrete continuous beam and T shape rigid frame, is a kind of newdeveloped structure of continuous beam. This structure has advantages ofcontinuous girder and T shape rigid-frame bridge. With the perfection of designtheories increasingly, and with the development of prestressed techniques andmodern methods in the bridge construction, the continuous rigid-frame bridge hasgotten rapid development in the internal and external bridge engineering. As far asthe condition of forces, it is more complex than continuous girder and T shapesystem. In the whole continuous rigid-frame bridge, the joint structure between pierand girder is a key location which has most complex stress states. Therefore,determining the stress in the joint structure is a very important research work for thestructural optimization.In this thesis, taking a prestressed concrete continuous rigid-frame bridge as anengineering background, the stress analysis for the joint structure has beenperformed with the method of three-dimension photoelasticity frozen stress andfinite element computation under the stress states of different working conditions. Itshows that the results from experimental stress analysis agree with calculating dataof finite element numerical method very well.Besides, in order to obtain experimental data, the applications of digital imageprocessing techniques to photoelasticity fringe patterns are also studied. Theapplications mainly include isochromatic fringe multiplication and isoclinic fringeseparating and sharpening. A single fringe pattern is increased by three times withthe trigonometric function method. The isoclinic fringe is perfectly separated withthe image logarithm subtraction method, and the isoclinic fringes are sharpened, andit makes the extracting of central lines of fringes become easier. A utility imageprocessing technique, called extreme value of gray scale combined with curvefitting method, is used and the central lines of isoclinic fringes are extracted by thismethod successfully. The speed of process is raised and the precision is improved.While the joint structure between pier and girder is computed with finiteelement analysis, three dimensional model is set up with software SolidWorks inthat finite element model must be accurate and perfect for reflecting the complexstructure shape. Then, three-dimensional model is inputted into ANSYS through thegraphic interface. Therefore, the precision of computation is improved. The finiteelement analysis results of the structure under adverse loading prove that the designis realizable and reasonable, and provide a reference for designing best structureshape.The results obtained with model experiment and finite element analysis arehelpful for comparing the structure schemes, and for optimizing the structure designand construction. The results have already applied to actual engineering, and madegreat significance.