Monitoring of Bridges Based on Natural Frequency Measurements

Dynamic analyses of the representative concrete bridge superstructures with spans up to 50 m, have been utilized to check the load-carrrying capacity and serviceability of bridges and overpasses on newly Croatian highways. Traditional non-destructive evaluation methods, such as acoustic emission, ultrasonic, thermograph, visual inspection and vibration measurements have been often employed to assess the structural integrity of a bridge. These methods, however, do not produce quantitative damage information that can be used to design a repair or assess the safety of the damaged structure. This shortcomings can be overcome when vibration measurements are used with the system identification algorithms. The study reported in this paper is the first stage of a research aimed at developing an effective and reliable monitoring method for structural damage identification. A computational procedure for structural damage identification using only the measured natural frequencies is proposed. A laboratory test was performed on a simply supported reinforced concrete beam to demonstrate the effectiveness of the proposed method. The results of the damage identification procedure show that this method can accurately locate the damage and predict the extent of the damage.