361 - A Study to Use a Triaxial Accelerometer to Assess Bridge Scour Depth

In recent decades, Taiwan has experienced a growing occurrence of flash floods during the rainy season. These fast-flowing, sediment-laden torrents pose a significant risk to the stability of bridge piers. It is imperative to employ advanced and precise technologies for pier scour assessment in disaster prevention. However, conventional methods often incur high field monitoring costs and rely solely on physical hydraulic parameters, often yielding inaccurate results due to the intricate nature of field flow conditions. To tackle this challenge, emerging vibration-based monitoring technology offers an innovative approach to estimating scour depths around bridge piers. This study explores the amalgamation of hydraulic data and vibration signals into a comprehensive formula for scour depth estimation. Dimensionless analysis was employed to derive this formula, followed by a series of carefully designed laboratory experiments to determine the necessary coefficients for its practical application. In this research, a triaxial accelerometer was designed and deployed to measure vibrations at the bridge piers, and the fast Fourier transform was utilized to convert amplitude-based signals into the frequency domain. The fundamental concept underlying this approach is that riverbed erosion leads to a reduction in the loading capacity of the pier foundation and alters the structural stiffness, subsequently influencing the overall structural vibration response. Furthermore, this study also investigated various pier models with varying degrees of stiffness to elucidate the relationship between vibration frequency and the current flow. The objective of this study is to provide a more precise and effective method for estimating scour depths around bridge piers, thereby enhancing early warning capabilities and mitigating potential bridge damage.