Applicability of Fatigue Crack Detection with Infrared Thermography Camera for Bridges in Denmark

This paper reports on the applicability of fatigue crack detection with an infrared thermography camera, the T-gap method, to a steel bridge in Denmark. The T-gap method is a non-destructive test developed in Japan and does not require approaching close to the bridge members, unlike visual inspections. The principle of the T-gap method is to measure the thermal profile of the welding point. One of the crucial factors generating the temperature gap is the solar altitude, and there is a smaller solar altitude in high-latitude areas, so it is unclear whether the T-gap method is more applicable in higher-latitude areas than Japan. Thus, the trial of the T-gap method in Denmark, which is located at a higher latitude than Japan, was planned to grasp the method’s applicability. As the results of trials, the T-gap method successfully detected both locations and the length of cracks even in Denmark.