Abstract: A frame structure is regarded as the object of research,wavelet analysis is applied to determine the location of damage of frame structure and the neural network method to identify the damage degree.The principle of strain mode parameter identification of damaged frame structure is given and thus a wavelet neural method for identifing damage structure is proposed.Through the establishment of damage identification method of vibration mode and strain mode,the framework crack positions under 9 different working conditions were identified,and the identifying effects in the two modes were compared. Then the vibration parameters and strain parameter were undergone continuous wavelet transform to obtain the two maximum mode parameters. Neural network was applied to identify the damage degree of structures through simulating the nonlinear relationship between the maximum of wavelet coefficients of the structure and the damage degree,and the damage identification effects in the two modes were compared.The numerical analysis indicates that the wavelet neural network can identify the damage location and degree of structure effectively,and the accuracy of damage identification method based on strain mode is better.

Key words: frame, wavelet transform, BP neural network, structure damage, strain mode, vibratory mode