Frequency Shift Curve Based Damage Detection Method for Beam Structures

Vibration based damage detection methods play an important role in the maintenance of beam structures such as bridges. However, most of them require the accurate measurement of structural mode shapes, which may not be easily satisfied in practice. Since the measurement of frequencies is more accurate than that of mode shapes, this paper proposes a frequency shift curve (FSC) method, based on the equivalence between the FSC due to auxiliary mass and the mode shape square, which has been demonstrated to be effective in structural damage detection. Two damage indices based on the FSC are developed, which are called the local outlier detection index and the global outlier detection index, respectively. The efficiency and reliability of the proposed method are demonstrated by numerical simulations and experimental results. Compared with traditional methods, this method can provide reliable results without the requirement of fixing many sensors on the structure.