Signal Processing for Fast RC Bridge Slab Damage Detection by Using UHF-band Radar

Maintenance costs for infrastructures, for example bridges, have been increasing especially in developed countries. The slabs are apparently important parts in bridges, however the structural condition evaluation requires lots of manpower and really time-consuming because dense hammering tests should be conducted in present inspection method. To overcome this difficulty, a non-contact inspection technique using radar is focused on in this research. Radar techniques have been utilized in the fields of mine-search, oil-source search, geographical archeology etc. However, those searches are done by just visually checking reflected-wave image and their evaluation strongly depends on the inspectors' ability and expertise. To more effectively utilize those radar techniques in bridge slab condition evaluation, the analysis of the reflected wave signals should be made automatic, fast and objective because huge amount of bridges to be inspected exist. In this research, to detect the damage of slab, some signal processing techniques for the reflected wave signal measured by UHF-band fast scanning non-contact SF-CW type radar are proposed, and their validity are shown by applying them to the signals obtained in real field bridge decks and full-scale bridge deck models in which some ideal damages are embedded.