Seismic damage evaluation of RC mem bers based on vibration characteristics

Damage identification methods for repairing and restraining reinforced concrete are important in light of the frequent earthquakes in Japan. Usually, structural damage is checked by visual observation, but it is difficult to evaluate the maximum response displacement and to identify the location of damage by sight alone. In this study, conductedin reinforced concrete beams forced vibration test and tlexural loading. In the experimental results of the global longitudinal vibration tests (excitation of the axial length direction), the natural frequency decreased to about 60% from the undamaged condition by an approximate plasticity rate of δIδ_y, = 2 (deformation ratio based on the yield displacement) in all of the beam specimens. The degree of damage to the RC member was concluded that could be evaluated by changes in natural frequency. Moreover, it has been found that the local dynamic response could be measured using high-frequency excitation in the section height direction. lt was shown that the damage location could be identified based on the local dynamic response.