NON-DESTRUCTIVE EXAMINATION METHOD OF CRACK DETECTION IN PAINTED STEEL BRIDGE MEMBERS

This study summarized non-destructive methods and evaluates their reliability and adaptability for the detection of fatigue cracks in painted steel bridge members. On the painting, it was possible to detect small cracks up to 5mm length with oxide formation by visual examination. And cracks with length longer than 5mm were detected by the eddy current examination with the suitable coil and frequency of the current. However, these were poor in the estimation of crack length. A combination of these examination over the paint and the close examination after removing the paint would be a superior detection method. For the estimation of the crack length, the magnetic particle examination was found exellent, allowing the detection of cracks with length longer than 2mm with accuracy of better than 1mm provided the paint was removed.