Abstract
This fundamental research is concerned with the crack detection of a concrete pillar combined with a concrete hexahedron, which is a model of the base pile of a bridge pier. Stationary waves are generated in the pillar and the hexahedron by hitting the head of the concrete hexahedron with a hammer. An acceleration pickup on the hexahedron observes the stationary waves generated inside the concrete pillar through the concrete hexahedron. The proposed method measures not only the length of the pillar but also the depth of the crack in the pillar by modeling the sensor output as an output of a linear dynamic system with unknown parameters and applying a maximum likelihood method.
