A Strategy for Optimal Sensor Placement in Modal Signal-to-noise Ratio-based Structural Health Monitoring

In structural vibration monitoring, the sensor layout scheme directly affects the identification accuracy of structural modal parameters. Aiming at the problem of operational modal identification, the concept of modal signal-to-noise ratio is proposed to characterize the difficulty of modal parameter identification of each order, and the influence of external random load amplitude, distribution and sensor noise level on the optimal layout of sensors can be considered. In order to balance the influence of each mode to be measured on the sensor layout scheme, the optimal layout of vibration monitoring sensors is realized by maximizing the minimum modal signal-to-noise ratio and minimizing the maximum off diagonal element of the modal assurance criterion (MAC) matrix. For the solution of the optimization problem, the subset simulation algorithm is selected to verify, and the effectiveness of the proposed method is verified by the modal test of the beam bridge model in the laboratory. The optimization results of measuring points show good linear independence and large enough modal signal-to-noise ratio.