Fatigue Resistance of Traffic Signal Mast-Arm Connection Details

Changes in the AASHTO Specifications and an increasing rate of fatigue related problems have raised awareness of fatigue concerns in traffic signal mast-arms. Prior research has indicated that the most commonly used connection details exhibit poor fatigue performance. This study was initiated to confirm the previous research results, as well as to investigate a larger variety of connection details and a weld treatment method. During this study, 55 full size mast-arm connection detail specimens were tested for fatigue resistance. The results indicate that the Ultrasonic Impact Treatment weld treatment can significantly improve the fatigue life of a fillet-welded socket connection detail. Several other connection details exhibited improved fatigue lives; however, the improvements were not as significant as the UIT treated specimens.