Wind-Induced Displacement Analysis for a Traffic Light Structure Based on a Low-Cost Doppler Radar Array

This study is concerned with the analysis of the displacement measurements simultaneously retrieved from multiple Doppler radars placed at different positions of a traffic light's mast. Currently, the structural health monitoring (SHM) works based on portable Doppler radars consider primarily methods for the extraction of displacement measurements. However, other measurements in the form of instantaneous natural frequencies and mode shapes can also be calculated with the use of Doppler radars arranged as an array. In this article, the wind-induced vibration displacement analysis based on a low-cost Doppler radar array is proposed. The sensitivity of the proposed array to changes in the instantaneous natural frequencies is evaluated. In addition, the structural modal analysis based on a Doppler radar array operating in the passive backscattering mode is demonstrated. The accuracy of the measurements obtained from the radars' demodulated data is compared with the accelerometer-based measurements. The ability of the proposed array to provide instantaneous natural frequency measurements and structural modal analysis is validated by the experimental results.