Accurate Identification of Cable Natural Vibration Characteristics Using the FDD Method to Improve Tension and Bending Stiffness Estimation Accuracy

Abstract

In bridge cable maintenance, a method for indirectly estimating tension from natural vibration characteristics obtained using Fast Fourier Transform (FFT) has been widely adopted. However, to achieve reliable cable maintenance, improving the estimation accuracy of natural vibration characteristics is essential, which necessitates the selection of an appropriate estimation method. This study focuses on the Frequency Domain Decomposition (FDD) method, which estimates natural vibration characteristics using only structural response data, and evaluates its estimation accuracy in comparison with the FFT method. Through validation based on cable experiments, it was confirmed that the FDD method provides higher accuracy in estimating mode shapes, particularly for higher-order modes. Furthermore, using the estimated natural vibration characteristics, cable tension and bending stiffness were determined and compared with true and design values. The results showed that the FDD method achieved superior accuracy in estimating both cable tension and bending stiffness. From these findings, it was confirmed that replacing the FFT method with the FDD method improves the estimation accuracy of cable natural vibration characteristics, leading to enhanced accuracy in estimating cable parameters.