Local Vibration Testing and Damage Evaluation for RC Bridge Decks

Abstract

The effectiveness of local (through-thickness) vibration testing, using a portable vibrator, is examined for determining damage locations and conditions within reinforced concrete (RC) bridge decks. The local vibration tests were conducted on deck specimens containing voids, for measuring resonant frequency during standing vibration. Wave propagation analyses based on a finite difference time domain (FDTD) method were then used to interpret the experimental results. It was shown that diffraction of waves around the void decreased the resonant frequency as the void size increased. As practical examples, local vibration tests were conducted on a deteriorated, decommissioned RC deck and bridge decks in service. The tests indicated that local resonant frequency was decreased by internal cracks within the deck. Resonant frequency distributions of the decks were also determined. The testing method is found to be applicable to detecting damage within actual bridge decks, even when the deck surfaces are covered with asphalt overlays and carbon fiber sheets. Moreover, periodic measurements could be used to evaluate the rate of deterioration of the bridge deck.