A novel inspection method for orthotropic steel decks using phased array ultrasonic testing

Over the last decade, fatigue cracking has been observed at the weld joint between the trapezoidal rib and the deck plate in many orthotropic steel deck bridges in Japan. Fatigue cracks initiated at the rib-to-deck weld root can cause pavement damage and thus impair transportation safety. It is necessary to detect and repair such fatigue cracks at the early stage of development. This paper presents a novel inspection method for the rib-to-deck weld of orthotropic steel decks with the aid of phased array ultrasonic testing. Automated scanner holding twin phased array ultrasonic probes is developed to simultaneously inspect the deck plate and the weld bead for internal part-through cracks. The developed inspection method is implemented at the Meiko-Chuo Bridge, a steel cable-stayed bridge carrying the Isewangan Expressway over the Port of Nagoya, and its performance is verified.