Experimental Study on Damage Detection of Non-uniform Steel Pipe Beam Using Impedance and Natural Frequency

Abstract

As the importance of steel pipe structures, widely used in facilities, increases, the development of health monitoring techniques is more required. This study experimentally detects damage to cantilever-type steel pipe beams with step changes their cross-section properties in the longitudinal direction. The impedance signal and acceleration were measured together for more accurate damage detection. Impedance and free vibration tests were performed for each intact and damage case, gradually increasing the damage severity to 9 steps. To analyze the impedance signal, two damage indices were used, and the 1st, 2nd, and 3rd natural frequencies were obtained using the measured acceleration. I found that the variance in the impedance damage index increased as the damage severity increased. The variation of the natural frequencies and impedance damage indices according to the damage progress were compared, and it has been found that the impedance damage indices are sensitive in early damage stages, and the change of the natural frequency is relatively large above a certain degree of damage. Therefore, if the impedance-based method and the acceleration-based method are complemented, it is supposed that more reliable damage detection of the steel pipe structure is possible.