Development of digital hammering inspection technology to evaluate the fixed condition of steel plate embedded in concrete

Digital hammering inspection technology using an acoustic emission (AE) sensor has been developed to evaluate the fixed condition of steel plates embedded in concrete. Since supporting structures for such equipment and pipes are welded to the plates, the reliability of the plates should be extremely high especially in nuclear facilities. The development was carried out through mock-up tests and FEM analysis as well as field application tests. It was confirmed that the embedded plates are in the state of being firmly fixed to the concrete when the hammering inspection index of "vibration duration" is below 20 ms. In addition, the stud welded on the back surface of the embedded plates has standard length, when the hammering inspection index of "natural frequency" close to the stud is higher than 1900 Hz. (author)