Abstract
Bolts and bolted connections are indispensable in most steel structures today. In civil engineering field, especially in bridge structures, bolts of large diameter are frequently used in very important portions such as shoes, expansion joints, cable anchorages and so on. Recently, accidents caused by fatigue failure of these bolts have been reported and importance of maintenance has been strongly noticed.
This research is to establish reasonable non-destructive detection method for fatigue cracks of bolts in their service conditions. Two types of ultrasonic testing method were proposed and their detection performances of fatigue crack were examined by fatigue test of bolts. From this experiment, data on fatigue crack growth and fatigue life of bolts were obtained and accuracy of fatigue crack detection by proposed ultrasonic testing was confirmed. As the results, possibility of rational supervision system for bolts in use was shown.
