Study On Damage Identification Of Simple Supported-To-Continuous Bridge Based On Curvature Mode Theory

The bridges are corroded by the environment and harmful substances during the construction and service inevitably, such as overload, earthquake, the structure fatigue, material aging, defect and man-made sabotage, causing the damage of different degree and reducing the actual bearing capacity of the bridges. The bridges often collapse due to the presence of structural defects and damages. The effective long-term health monitoring, regular safety evaluation and the reinforcement for the bridges to ensure the safety of the bridges have become the most concerned problems for the departments of bridge management. In this paper, the simply-supported continuous bridge model was set up based on20m to40m general diagram produced by the ministry of communications, the modal parameters of the continuous beam was obtained by numerical calculation and studying the impact of different section, different span and different span number on natural vibration characteristics of the bridge. And the damage identification of the bridges was studied based on curvature mode theory, the results show:1、Modal curvature method, the curvature modal differential method and absolute deviation of curvature modal method are all able to identify the damage of the bridge, the probability of small misleading peal appears in the low order modes is small. The effect of damage identification is good. The curvature modal absolute difference recognition effect is better than the other two kinds of methods. Curvature modal differential method does not need the raw data of the bridge to identify the damage of the structure.2、The three kinds of identification methods based on curvature mode theory are all relating to the selection of bridge vibration mode. When the location of damages is near the nodes of mode shape, the three kinds of methods could not identify the damages.3、In the single damage identification, absolute deviation of curvature curve will have a mutation at the damage location. Degree of mutations associated with damage degree, damage degree, the more obvious mutation. The structure with several damages, under the same damage degree condition, absolute deviation of curvature modal of the increment of different positions is different and independent. Absolute deviation of curvature modal method could identify the damage degree.4、The damage identification method based on the changes of frequencies depends on the raw data of the bridge. We could identify the damages of the structure by the changes of frequencies, but we can not decide the damage location and degree of the damage.