Damage Identification For Multisupported Beam Based On Wavelet Analysis

The multisupported beam structure is a common form of bridge,and widely applied in engineering. Under the wind or earthquake loads, and natural environment erosion, some local structural damage appear and its mechanics character degradation of stiffness and strength. This degradation has the directly effect on the structure dynamic character. Wavelet transform is a analysis method both for time and frequency domain, and it adapted well to singularity analysis for its multi-resolution. Based on study of civil and abroad scholars to structural damage identification methods in this paper, standard deviation of acceleration used as damage index, and wavelet transform is used for identification of the site and degree of damage.Dynamic response information of collectting is limited, whether field test or numerical analysis. Each decomposition amount could generally appeared Gibbs phenomenon at its boundary while wavelet transform. After compared the typical methods by treating edge problem of the signal with limited time zone, method of information expansion based on curve fitting is proposed in the paper, and validated this method by numerical example.For the multisupported beam with uniform stiffness,the method of expanding the use of information and inhibit the effects of Gibbs oscillations, the multisupported beam structures for damage detection, wavelet transform to identify structural damage information of the range extends Dao whole structure, particularly the border region is a structure; for more multisupported beam damage, due to injury as well as between the impact of their bearing, structural damage location is difficult to identify. To this end, the introduction of information truncated methods to eliminate these effects and to develop methods of combining information on the response information to process, complete and accurate identification of damage location.Finally, the wavelet coefficients modulus maxima points corresponding Lipschitz index to determine the extent of structural damage. On the multisupported beam under moving load displacement of the structure of the continuous wavelet transform variance curve, with the damage of Lipschitz index of the degree of damage location, damage occurred in the number of injuries between the effects of load size, load speed variation.