Passive Tap-scan damage detection method for beam structures

Efficient damage detection technologies are highly demanded in the maintenance of bridge structures. For this purpose, the authors have developed the active Tap-scan damage detection method, which can extract bridge damage from the acceleration of a passing vehicle mounted with a shaker. Although this method can be efficiently implemented in a noisy environment with normal traffic, the damage detection accuracy could be deteriorated by the fluctuation of vehicle velocity, and the portability of the vehicle is impeded by the cumbersome shaker system. To solve these problems, this paper proposes a passive Tap-scan damage detection method, which uses an automatic driving vehicle with specially designed tire treads to scan the bridge. Instead of using the shaker, the tapping force is passively generated by coordinating the vehicle velocity with the periodic pattern of the tire tread. The theoretical basis of this method is firstly established on the analysis of the interaction between a simply supported beam and a passing vehicle with tapping contact forces, as well as the analytical solution of the deflection of a damaged beam subjected to a unit point force. Then, in-house experimental damage detection results of a simply supported aluminium box beam are reported to demonstrate the effectiveness of the proposed method.