To effectively uncover overall stiffness changes in structures and address challenges related to accurately identifying modal damping,particularly in complex bridge operations,this study presents an innovative method for determining the modal damping ratio of complex bridges.This approach enables precise and efficient analysis using a limited number of acceleration sensors.Initially,the variational mode decomposition method is utilized to accurately separate measured nonlinear vibration signals into single-frequency modes.Subsequently,these decomposed signals are processed using Hilbert transform and impulse response functions to establish a method for determining the modal damping ratio.An in-service double-layer steel truss arch bridge with extended track-sharing layers is chosen as the empirical research subject,and the acceleration response signals from its main beam are collected.Through the application of variational mode decomposition and impulse response function methods,the signal characteristics are effectively analyzed,leading to the determination of the structure's frequencies and damping ratios.A comparison of these frequency data with results from finite element model analysis validates the accuracy and reliability of the proposed method.
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