Damage Identification Of Continuous Rigid Frame Bridges In Service Under Moving Loads

The rapid development of the traffic system has led to an increase in bridge construction,and people have paid more attention to the functionality of the bridges during normal use within the design life.Nowadays,due to the increasing frequency of bridge collapse incidents,scholars everywhere are paying more and more attention to the system of bridge health monitoring.In order to discriminate the damage of bridge under the action of dynamic load,this paper uses the cofi5 continuous wavelet transform of acceleration response to identify the damage of simply supported beam and continuous rigid frame bridge under the factors such as the speed of load movement,load size,and noise.Methods were studied.Based on the numerical analysis and calculation,the possibility of cofi5 wavelet transform to identify the damage of the simply supported beam's mid-acceleration response under moving load is studied.Based on this,a cofi5 wavelet was used to identify the single-position damage and multiple positional damages of the continuous rigid-frame bridges' mid-acceleration response using wavelet transform,and the moving load speed,moving load size,and Damage degree and noise impact on damage identification.The main research work of this article is summarized as follows:(1)This paper introduces the basic theory of the widely used damage identification technology at the present stage,compares the advantages and disadvantages of various methods and the scope of application,and provides reference for different purposes and different requirements for damage identification.Secondly,the theory of wavelet analysis is introduced in detail,which lays a theoretical foundation for the subsequent use of wavelet analysis.(2)ANSYS software is used to establish a well-supported beam model and the finite element model under different damage conditions.Under the action of moving load,the damage is identified by the cofi5 wavelet transform of the acceleration response difference in the span.The specific steps are as follows: Acceleration history in the intact state and the damage state are obtained respectively,and then the acceleration response difference is obtained.Then,the acceleration difference is subjected to wavelet transform,and the damage is identified by observing the peak value of the wavelet coefficient.The influence of moving load speed,moving load size,damage degree and noise on the discriminative damage of simply supported beam is analyzed.(3)Based on the damage identification method of simply supported beam,the cofi5 wavelet was used to carry out the wavelet transform of the mid-span acceleration response of continuous rigid frame bridge to identify single position damage and multiple position damage,and analyze the moving load velocity and moving load.The effect of size,degree of damage,and noise on damage identification.The research results show that the method of damage identification is affected by the load moving speed.When the speed is less than 10m/s and the SNR is higher than 40 dB,the damage location can be determined accurately.