Displacement Response Reconstruction Of Bridge Subjected To Moving Load Based On Data Fusion

Moving load induced displacement directly reflects bridge stiffness,and it is normally used for bridge health monitoring and condition assessment.The traditional direct method of displacement measurement has some limitations,such as the need for a fixed reference point and the low measurement accuracy.However,the indirect method that reconstruct displacement using acceleration response or strain response has some shortcomings,such as low-frequency partial drift and difficulty in determining the position of neutral axis.Therefore,obtaining the bridge displacement under moving load accurately,economically and conveniently has become an urgent problem.Aiming at the displacement reconstruction of bridge under moving load,a displacement reconstruction method based on strain and acceleration data fusion is proposed in this paper.Combined with the displacements derived from acceleration and strain,this paper proposes a method to calculate the neutral axis correction factor accurately.Further,the paper proposes a displacement reconstruction method for bridge under moving load,using the data fusion of acceleration and strain response.The numerical examples and laboratory experiments are carried out to verify the effectiveness and stability of the proposed method.Finally,the application of reconstructed displacement in bridge damage localization and impact coefficient calculation is investigated.The main contents of this paper are as follows:(1)The research status of traditional bridge displacement identification methods and the application of bridge displacement under moving load in bridge condition assessment and health monitoring are introduced in detail.(2)The bridge displacement reconstruction method using acceleration and strain response are introduced firstly,and their advantages and disadvantages are analyzed.Combined with the displacement reconstruction method based on acceleration response and strain response,a new neutral axis correction factor is proposed to locate the neutral axis position quickly and accurately,which provides a foundation for improving the accuracy of displacement reconstruction method based on acceleration and strain response.(3)A bridge displacement reconstruction method under moving load based on data fusion is proposed.Based on the variational principle,the control equation of the data fusion method is derived.The bridge displacement under moving load is divided into acceleration derived displacement and pseudo static displacement,and a low-pass filter is designed to extract the pseudo static displacement from the corrected strain derived displacement.The reconstruction process of bridge displacement under moving load based on acceleration and strain data fusion is provided.The effectiveness and adaptability of the proposed method are verified by numerical examples and laboratory experiments,and the effects of the number and location of sensors,test noise and other factors on the accuracy of reconstructed displacement are systematically investigated.(4)The reconstructed displacement is successfully applied to bridge damage location and impact coefficient calculation.The applications of pseudo static displacement in reconstructed displacement in bridge damage location and impact coefficient calculation are investigated.Numerical example indicates that the pseudo static displacement extracted by the proposed method is insensitive to load moving speed and damage quantity when used for damage location,and has higher accuracy than the traditional Peak-Valley method when used to calculate impact coefficient.