Acoustic emission detection and monitoring of highway bridge components. Final report

Abstract

Over ten thousand highway bridges in the United States reach their fatigue life limits every year. This emphasizes on the need for developing an effective method for evaluation of the structural integrity of those structures. The current inspection of highway bridges depends on the visual examination, ultrasonic and occasional radiographic techniques that have shown a low degree of reliability in detecting small cracks. Application of acoustic emission technique in the aerospace and nuclear industries have proved considerable capabilities in detecting extremely small crack growth increments. This technique was used in this study to characterize acoustic emission signals that are related to the growth of fatigue cracks in bridge components. A number of welded and rolled beams and small specimens were subjected to cyclic loadings in the laboratory. Acoustic emission data were obtained and evaluated in the time and frequency domains. It was concluded that the acoustic emission technique may provide a positive solution to the existing problem of detecting small fatigue cracks in highway bridge structures.