Abstract
Vibration-based methods are widely used in bridge assessment, yet their engineering interpretation for serviceability evaluation remains inconsistent across studies and national practice. This paper comparatively analyzes international practice in the vibration diagnostics of beam bridges with a focus on how measured dynamic response is translated into conclusions about operational suitability. The analysis covers field-oriented studies and review sources and compares excitation strategies, sensor layouts, measured parameters, interpretation routes, and links between diagnostic results and engineering decisions. Across the reviewed studies, the most frequently used indicators are natural frequencies, mode shapes, damping characteristics, and vibration response levels, since these quantities are sensitive to changes in stiffness, boundary conditions, and structural deterioration. The comparison also shows that these indicators are not equally informative across all field conditions and do not, by themselves, provide a uniform basis for serviceability assessment. Their practical value depends on the test organization, signal interpretation, and the extent to which vibration data are combined with structural models, inspection context, or baseline states. The paper identifies the most transferable findings from international practice and highlights considerations relevant to bridge networks that require practical, selective, and reproducible assessment procedures, including those in Kazakhstan.