Structural Monitoring of a Defective Steel Beam Model Based on Image Changes in Power Spectral Density

Using power-spectral density (PSD) analysis for structures, we evaluated defects following a widespread research trend. During the structure’s operation, PSD not only demonstrated its structural integrity at the time of surveying but also predicted future changes in the structure. The present research used changes in PSD as a key feature for monitoring a beam structure’s shearing patterns. Two shearing models—side shearing and shearing under the beam—revealed changes in the shape of PSD images that corresponded to degrees of defect in the different shearing models. We applied these results to the monitoring of simple actual span structures over a long period of time. We monitored the structure’s operational status over time to examine the increased influence of structural defects based on significant changes in the PSD regarding spectral amplitude and spectral width. The frequencies initially found in the high-frequency region of PSD tended to shift toward the lower-frequency regions before disappearing entirely. In the future, the results of this research may improve the evaluation of structural integrity through variations of PSD in vibrational spectral shapes.