Remote and Digital Inspection for Concrete Bridge by Laser Hammering Inspection

We are developing and operating the laser hammering system (LHS) that is non-destructive remote sensing device for concrete infrastructures. LHS can digitize the hammering test which is current mainstream of the inspection of concrete by using an impact laser (short-pulse laser), laser Doppler vibrometer, scanning system and camera. In this study, long-range LHS (applicable distance of 30 m) and small LHS (160 kg weight, for use on aerial work platforms) are developed for the bridge inspection. Long-range system succeeded on measurement of the concrete specimens of class 2 and 3 defect which were identified by active inspectors, and real defect of class 2 on bridge on use at the distance of 30 m. Small LHS succeeded on generation the surface vibration of the concrete specimens of class 2 and 3 defect which were identified by active inspectors. It indicates Long-range LHS and small LHS satisfied the inspection requirement as the support tool of hammering test prescribed by Japanese government. These devices are available for support to inspectors and digitalization of concrete sound status to achieve smart infra-maintenance.