Long-Term Bridge Health Evaluation Using Resonant Frequency Changes under Random Loading Conditions

This study explores theoretical insights and experimental results on monitoring load-carrying capacity degradation in bridge spans through frequency analysis. Experiments were conducted on real bridge structures, including the Binh Thuan Bridge, focusing on analyzing the power spectral density (PSD) of vibration signals under random traffic loads. Detailed digital models of various bridge spans with different structural designs and construction periods were developed to ensure diversity. The study utilized PSD to analyze the vibration signals from the bridge spans under various loading conditions, identifying the vibration frequencies and the corresponding response regions. The research correlated the observed frequency changes of PSD with the actual deterioration of the bridges over time, identifying patterns that indicate a reduction in stiffness. Experiments demonstrated that frequency changes, particularly in high-frequency regions, are directly related to a reduction in the stiffness of bridge spans. This supports the hypothesis that natural frequencies can serve as effective indicators of structural damage. Furthermore, the emergence and shift of resonant frequency regions provide valuable insights into the extent of damage in actual bridge spans, highlighting the potential for using changes in resonant frequency regions as a new tool for structural damage detection.