Study On Damage Identification Method Of Simply Supported Beam Based On Lifting Wavelet Transform

With the development of bridge construction,various new types of bridges have been built rapidly.However,the bridges are affected by external environment,static and dynamic load and other factors in the process of operation.Many problems such as aging,deformation,cracking and so on have appeared in these bridges,and it may cause the collapse of the structure if the safety problems can't be found in time,resulting in huge economic losses and casualties.Therefore,it is necessary to explore an effective method of damage identification.In this paper,based on the basic theory of lifting wavelet transform,the damage identification of simply supported beam bridge is mainly carried out in the following aspects:(1)The dynamic response of the simply supported beam bridge under the impact load and the moving vehicle load are analyzed by the lifting wavelet transform respectively,and then the damage is identified according to the structural energy curvature index.Numerical simulation result shows that this method can achieve the goal of identifying damage.(2)The noise robustness of the of energy curvature method is analyzed,and the result shows that the robustness of the method is poor.Therefore,the noise in dynamic response should be reduced to ensure the reliability of the recognition result before the damage identification.Furthermore,this paper discusses the effect of the load moving speed,the measuring point density and the vehicle jumping to the recognition result.The experimental model under the moving vehicle load is designed according to the corresponding relationship between the theoretical model and the structural prototype,which verifies the validity of the identification method.(3)This paper proposes a method to identify the damage of simply supported beam by combining the lifting wavelet transform and the cross correlation function.Through numerical simulation and experiments,the effectiveness of the method is verified.The influence of noise on the identification results is discussed in this paper,and the results show that this method has good noise robustness,so it is more suitable for engineering practice.