Research On Bridge Damage Identification Method Based On Wavelet Analysis

Bridge is one of the vital parts of the traffic and transportation system. The healthy status of bridge structures is the premise for traffic and transportation system to operate normally. At present, some bridges appear aging, damage and crack, even breaking down collapses for some reasons, such as design, construction, management, natural disasters and so on. It has caused tremendous losses in the lives and properties of the people. Wavelet analysis is over the last decade an international frontier. Wavelet analysis method is the nature of spatial localization, that is, the signal in a point in the small-scale wavelet transform completely from the vicinity of the point determined by local information, its singularity detection signal has a unique advantage. So, Bridge damage detection method based on the wavelet theory has important theoretical and engineering applications.In this paper, the connections between the damage and modal parameter of the bridge is researched by the finite element model of the bridge is analyzed based on the wavelet theory. The damage bridges are analyzed using continuous wavelet transform by mexh wavelet (Mexican Hat wavelet), and the position of the crack can be identified by the modulus maximum of the wavelet coefficients.The fundamental of the method of damage identification using wavelet analysis is presented.The damage identification method based on wavelet analysis of the curvature modes is established in the paper. Taking continuous steel girders on elastic foundation for example, based on wavelet finite element methods. The rotation mode, strain mode and curvature mode are analyzed using continuous wavelet transform by mexh wavelet (Mexican Hat wavelet), and the position of the crack can be identified by the modulus maximum of the wavelet coefficients. Research on continuous steel girders damage identification method based on modal parameter and wavelet analysis is established. By the calculation and analylsis of the continuous steel girders which has different damages, its effectiveness has been proved.Taking the cable-stayed bridge for example, dynamic characteristics of cable damage, main girders damage and cable and main girders damage are researched by the calculation and analylsis of the damage cable-stayed bridge. The damage cable-stayed bridge is analyzed using continuous wavelet transform by mexh wavelet (Mexican Hat wavelet), and the position of the crack can be identified by the modulus maximum of the wavelet coefficients.The fundamental of the method of damage cable-stayed bridge identification using wavelet analysis is presented.Based on wavelet analysis theory, the damage identification method of the curvature modes, rotation mode and strain mode for bridges is presented. The model of finite element method for cable damage, main girders damage for the single tower cable-stayed bridge and the multi-tower cable-stayed bridge are established. Different damages are calculated and its effectiveness has been provde.This method may be useful in damage cable-stayed bridge identification.