The Research On The Damage Identification Of The Continuous Beam Bridge Under Moving Loads Based On Wavelet Analysis

Bridge there will be a variety of diseases which affect the structure safety and driving comfort in the process of operation of the structure, so the structure damage diagnosis timely is very important. In the traditional methods of structural damage detection, there are various defects, such as the need to interrupt the traffic, the arrangement of a large number of sensors, as well as the detection and diagnosis process is complex. Based on the dynamic response of bridge under the operating load detection method solve the above problem. But this method is mostly in the simple structure of the research more, and in the continuous beam structure with multiple degrees of freedom the research is less. The continuous beam structure as the research object, damage index and identification method of continuous beam bridge based on dynamic response and continuous wavelet transform based on moving load are studied. The results show that the method has good identification effect. The main research contents and results of this paper include the following aspects:1.Aiming at the shortage of traditional structural damage identification methods,emphasizes the structural damage identification method based on moving load, and the status of damage identification of continuous girder bridge are summarized.2.The theory of moving loads of two span continuous beam without damage and damage of the midspan dynamic response was deduced. Analysis shows that any cross structure damage has an influence on the structure of other cross response, which can be used to damage identification of structure response by arbitrary span continuous beam bridge.3.Damage identification method for continuous beam bridge based on any point acceleration response is proposed. The acceleration time history of a continuous beam bridge under moving load is obtained, and then the wavelet transform is carried out. A scale of wavelet transform coefficients can realize the identification of the damage,and identify the damage degree by the damage degree evaluation index. The effectiveness of this method is verified by the numerical simulation of a continuous beam bridge with three span continuous beam bridge. The effect of multiple damage locations, moving load speeds, different damage degrees and the effect of noise on the damage identification are studied. The study shows that the method is more affected by the load speed, and the damage location can be identified accurately at the speed of40km/h and below the 5% noise level.4.Calculate the logarithm energy of the acceleration response of continuous girder bridge. Then using wavelet packet decomposition and reconstruction to calculate the sample entropy of reconstructed signal, thereby we can got the structural damage index SPLE. The effectiveness of this method is verified by the numerical simulation of a continuous beam bridge with three span continuous beam bridge. The damage index can be used to identify the location of the structural damage, and the noise robustness of the index is analyzed. The results show that this index not only can identify the damage, but also has better noise immunity.