The loading process of a gantry crane with a rated lifting capacity of 41t is monitored,with the help of a portable electrical impedance testing system established in this study.The stress distribution cloud map of the crane during loading was determined by the finite element analysis method,and the stress concentration area was selected as the monitoring point.Four monitoring frequency bands were selected,and the electrical impedance signals of the piezoelectric sensors were measured before,during,and after loading of the crane.The results indicate that the overall impedance amplitude of the piezoelectric sensor shows a decreasing trend with the increasing of measurement frequency.In the high-frequency range,there are more peak and valley values of electrical impedance,which makes it more sensitive for structural damage monitoring.When there is no crack damage in the metal structure of the monitored crane,there is no deviation in the frequency corresponding to the peak and valley values of the electrical impedance during the entire loading cycle.
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