A new indicator is proposed to facilitate the detection of newly induced damage in reinforced concrete(RC) beams, based on the transient characteristics of nonlinear vibration. Two full-scale RC beams,one reinforced with externally bonded fiber-reinforced-polymer sheets, are tested to develop theproposed damage indicator. Both beams are statically and dynamically loaded to correlate thedynamic characteristics of the beams to the damage level. A phenomenological model is developedto simulate the ...