2015 Volume 22 Issue 87 Pages 87_47-87_56
Detection of fatigue cracks at rib-to-deck weld bead in orthotropic steel decks for highway bridges by conventional nondestructive testing (NDT) techniques generally entails many difficulties such as accessibility, inspection time, cost and crack detectability. This paper presents a study on the applicability of a newly developed NDT technique for rib-to-deck weld cracks based on the detection of temperature gaps caused by thermal insulation effect due to the existence of cracks. The use of infrared thermography for detecting temperature gaps provided high-performance remote and effective NDT technique. Detectability of fatigue cracks by the proposed technique was investigated in an actual bridge, in terms of crack length, weather conditions (ambient temperature, sunlight) and measuring conditions (specification of infrared thermography, object distance, spatial resolution). Further, the suitable season and time for the technique were also investigated from one-year temperature monitoring of the bridge. As a result, the effectiveness and practicability of the proposed technique was verified.