[301] Plenary Keynote Lecture: Development of NDE techniques for the maintenance of long-span steel bridges based on infrared measurement

Propagation of fatigue cracks from welded joints in steel bridges is one of the serious problems associated with the deterioration of ageing infrastructure. Inspection of deterioration such as fatigue damage or corrosion is necessary to ensure safety and to estimate the remaining strength of the steel bridges. In this respect, non-destructive testing (NDT) and non-destructive evaluation (NDE) techniques play important roles. The present author has been conducting cooperative research with Honshu-Shikoku Bridge Expressway Company Limited on the development of remote NDT and NDE techniques using infrared thermography for the effective maintenance of large steel structures. In this presentation, some experimental studies using infrared thermography are introduced relating to fatigue crack detection, estimation of fatigue crack propagation based on fracture mechanics and evaluation of strength recovery through repair work. Furthermore, a newly developed remote monitoring technique using a short-wave infrared camera for the detection of wear and deterioration of heavy-duty coatings is introduced.
Keywords: non-destructive evaluation, infrared thermography, thermoelasticity, fatigue cracks, steel bridges.