Applicability of fatigue crack detection with infrared thermography camera to bridges in Denmark

This paper reports that applicability of fatigue crack detection with infrared thermography camera, T-gap method, to the steel bridge in Denmark. T-gap method is a non-destructive test developed in Japan and does not need to approach closely to the bridge members rather than visual inspections. The principle of T-gap method is to measure the thermal profile of welding point. One of the crucial factors generating temperature gap is the solar altitude, so that there is less solar altitude in high latitude area and it is unclear that whether T-gap method is applicable in higher latitude area than Japan. Then, trial of T-gap method in Denmark, which is located at higher latitude than Japan, was planned to grasp its applicability. As the results of trials, T-gap method successfully detected both locations and length of cracks even in Denmark.