Journal of Engineering Research

For a 30-meter prefabricated PC simply supported T-beam bridge under the coupling environment of heavy-duty mining trucks and chlorides along the coast, a two-step inspection system of "drone high-definition photography + manual re-inspection" is constructed to conduct rapid screening of four types of apparent defects, namely bending, shearing, network shrinkage cracks and concrete spalling, at the operational window level. U-Net semantic segmentation achieves 92% recall of 0.1mm cracks, introduces crack density ρ and chloride salt to correct the threshold, and the on-site verification data error is less than 5%, providing a reusable quantitative model for subsequent BIM connection and precise allocation of maintenance funds.

Simply supported beam bridge; Disease inspection; Unmanned aerial vehicle; Acoustic emission; Analytic hierarchy process