The results of a series of harmonically forced tests
carried out on a reinforced concrete single-span bridge subjected
to increasing levels of an artificial damage are interpreted in
this paper. The deck structure of the bridge consists of a slab
and three simply supported beams. The damage is represented by a
series of notches made on a lateral beam to simulate the effect of
incremental concentrated damage. The variation of natural
frequencies shows an anomalous increase in the transition {}from
one intermediate configuration to the next damage configurations.
Vibration modes shapes show an appreciable asymmetry, despite the
nominal symmetry of the reference configuration of the bridge. A
justification of this unexpected dynamic behavior is presented in
this paper. The analysis is based on progressive identification of
an accurate finite element model of the reference and damage
configurations based on natural frequency and vibration modes
measurement. Finally, changes in modal curvature of the first two
modes evaluated along the main beams were successfully used to
identify the location of the damage.
