Study On Damage Identification Of Bridge Structures Based On Ambient Excittation

Vibration-based damage identification method is the leading method of nondestructive testing technique in bridge structure. As the development of mode identification methods and the capability of sensor, ambient excitation is becoming the mostly way of excitation. But the application of damage detection method based on ambient excitation is limited because of the low precision of dynamic parameter measurement and imperfection of early structural information. Base on the present research, the research works is explored and developed deeply for damage detection method of bridge structures based on ambient excitation in this paper, and research works on 4 aspects have been done around the purpose. (1)Study on mode identification of bridge structure based on ambient excitation Consider the practicability of damage detection, the damage identification of bridges ought to be based on ambient excitation. So, the modal analysis based on ambient excitation is very important for damage identification of bridges. In this paper, a new modal analysis and damage identification method is developed for bridge structures, in which the displacement mode and curvature mode can be obtained by nature frequency and so local damage are characterized by only the nature frequency measured from the damaged structures, in contrast with most of the existing vibration-based damage identification methods, which require both the nature frequency and other modal parameters measured from the damaged structure. By the method proposed in this paper, the displacement mode can be obtained as the same exactitude as nature frequency, contrast with most of the existing modal analysis method, in which the exactitude of displacement mode obtained from testing data is much lower than that of nature frequency. (2)Study on damage localization based on ambient excitation It is hard to localize the damage on operating condition because of the modal data can not be obtained completely. Based on the modal flexibility of field observation, a damage localization approach is developed for the bridge structure in this paper, in which damage is...