Research On Structural Damage Identification Of Girder Structure Base On Wavelet Packet Analysis

Long-span structure especially large bridge structure safety integrity and durability health monitoring during normal operation has gradually become academic and engineering research hotspot at home and abroad . Under the common function of disaster such as environmental erosion,materials aging,load long-term effects,fatigue effects,mutation effect and other disaster factors, Structure damage is unavoidable, Some component damage may even have expanded quickly. Bridge monitoring system are required to Prompt capture to moments when the the damage happen And can accurately identify the damage location. Thus it can provides the basis for engineering structure maintenance and management.Wavelet transform is a new mathematical tools after the fourier transform. It also has strong localization characteristics In the time domain and frequency domain. It can adopt gradually fine sample step to The different frequency ingredients. Focus to signal any detail, and is Considered to be the microscope of analytical signal. Wavelet transform is very sensitive to signal singularity, Can identify mutation information existing in structural response signal .So, we can use wavelet transform to singular signal detection,The SNR separation and the signal frequency analysis,extract damage characteristic,confirm structure damage degree and damage location. structure dynamic response signal is analyzed in this paper based on wavelet packet transform. For how to use wavelet packet analysis injury features extraction, identify the damage degree and structural damage location. Included damage locating with noise jamming ,made a preliminary exploration. It shows from theoretical analysis and experimental study that: Wavelet packet transform can not only determine the correct damage degree of discrimination, Also can undertake the small damage cases damage location, And can correctly identify damage location under the influence of the noise.The main contents are as follows:①Introduces the structural damage warning basic ideas of energy spectrum based on wavelet packet , And the selection of wavelet function, Wavelet packet decomposition level determination, Structure damage characteristic vector construction, The definition of structural damage warning index are described in detail.②By analyzing experimental data of a reinforced concrete simple beams and prestressed concrete box girders, All the damage degree of load conditions are carried out. Contrast with random subspace frequency identification method, Explain benefits of wavelet packet energy method.③Discuss the effects of arrangement of measuring to damage degree discrimination.④It is introduced that structure damage location principle based on wavelet packet band energy, and establish a simple beam structure model with ANSYS. Discuss its damage location effect in small damage situations for different damage location of a single damage and much .⑤Discuss damage location effect in different damage location, different damage degree and different noise level⑥A injuryed steel beam with low SNR signal is positioned accuracyly.