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As a global vibration characteristic, natural frequency often suffers from insufficient sensitivity to structural damage, which is associated with local variations of structural material or geometric properties. Such a drawback is particularly significant when dealing with the large scale and complexity of sluice structural systems. To this end, a damage detection method in sluice hoist beams is proposed that relies on the utilization of the local primary frequency (LPF), which is obtained based on the swept frequency excitation (SFE) technique and local resonance response band (LRRB) selection. Using this method, the local mode of the target sluice hoist beam can be effectively excited, while the vibrations of other components in the system are suppressed. As a result, the damage will cause a significant shift in the LPF of the sluice hoist beam at the local mode. A damage index was constructed to quantitatively reflect the damage degree of the sluice hoist beam. The accuracy and reliability of the proposed method were verified on a three-dimensional finite element model of a sluice system, with the noise resistance increased from 0.05 to 0.2 based on the hammer impact method. The proposed method exhibits promising potential for damage detection in complex structural systems.

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Without the difficulty of applying particular excitations on arch dams, a method using the correlation coefficients of time-scale representations (CCTSRs) of seismic responses to identify the damage in transverse joints is proposed. The identification of damage using the CCTSR method is characterized by comparing the time-scale representations (TSRs) of paired seismic accelerations measured from two neighbouring points crossing the transverse joints horizontally. With the CCTSR method, the TSRs of measured seismic accelerations are produced with the continuous wavelet transform; the comparison of the TSRs is carried out by calculating the correlation coefficients. The correlation coefficients of the paired TSRs are combined with the defined damage intervals to evaluate the positions and severities of the damage. The method’s feasibility is numerically verified via the identification of the damage in transverse joints by discussing the effects of the wavelet functions, seismic excitations, and noise resistance. The method’s effectiveness is experimentally validated via the detection of the damage in transverse joints of a scaled arch dam model subjected to artificial seismic loads. The proposed CCTSR method can localize the positions of various damage scenarios and quantify the damage severities caused by progressive seismic loads.

Cracks of sluice hoist beams due to the load and aging of the material threaten the safety of sluice structural system. As the one of the main methods of damage detection, the nondestructive detection method based on natural frequency is still insensitive to local damage. Therefore, this paper proposes a method for hoist beams damage detection driven by resonance frequency band based on local primary frequency in the local mode. Firstly, the possibility of damage detection based on local primary frequency is discussed and the procedure of determining resonance frequency band is explained. Then the damage identification index based on the change ratio of local primary frequency is provided. Finally, numerical results demonstrate the correctness and effectiveness of the proposed method. The proposed method can provide reference for damage detection of hoist beams and health monitoring of sluice structural system.