ABSTRACT
Some bridge piers in a megacity such as Tokyo have been constructed by steel in the 1960s, because of the very strict construction limit. Most of the steel piers were welded at that time, when weld has been started to apply from the riveting. However, little attention was paid for the weld quality. The quality of some of the welded joints was not satisfactory. That caused fatigue cracking, especially at the intersection of three weld lines of the steel pier. Insufficient bevel processing resulted in an incomplete penetration. The objective of this study is to detect those incomplete penetrations by applying phased array ultrasonic test, because they are internal defects. A specimen of the beam column joint of almost the same dimension as the actual structure was made. By using the information of plate assembly and assuming that a volumetric incomplete penetration was a triangular prism shapes, incomplete penetrations could be detected.
