Research On Bridge Damage Detection By Dynamic Analysis

Based on the research Status of dynamics method of structural damage identification and some problems about it, the thesis mainly chooses two methods basing on frequency and curvature modal to analysis the damage of bridge. Finally, the author makes a modal test about a PMMA simple-supported box beam and makes a damage analysis using the actual modal parametersAnalysis of damaged bridge mainly uses numerical calculation. The numerical result clearly states that the damage in single location can be reacted by the changed rate of frequency and changed squared rate of frequency, but they can not identify damage in more than one location. Due to curvature modal, not only single damage but also damages in different location can be identified, and the accurate location of damage just needs low- curvature modal. The major factor which affects the identification effect should be the meshing degree. So in actual test, the spacing size between test points directly impacts the accuracy of damage identification. Owing to low-curvature modals can not absolutely reflect the situation of damage, damage index should be used to identify the damage with integrating high- curvature modal. When the damage occurred in an inflection point, the corresponding curvature modal becomes insensitive.The thesis takes a PMMA simple-supported box beam as the test model. Through the dynamic response analysis by ANSYS, extract the first three bending modal, simulate the damage, and then analyze the damage for locating the damage in theory. At last, through the model's modal test, extract the first three bending modals in the damaged and undamaged model for analysis. From the perspective of test, it verifies the feasibility of the technology for damage analysis based on curvature modal, and artificial method applies to the damage of model's damage simulation...