Testing research on defect monitoring of CFST internal holes

The monitoring test of internal hole defects of concrete filled steel tube was carried out. A monitoring method was proposed for measuring and analyzing the hole defects in the concrete filled steel tube, in which manufacturing embedded piezoelectric sensor by using piezoelectric material, by arranging the monitoring system and using the principle of wave analysis. Concrete filled steel tubular specimens with internal holes of different diameters and sensor monitoring groups with different spacings were designed experimentally. The stress wave measurement results were compared and analyzed from the perspective of time-domain analysis based on amplitude and wave velocity and frequency-domain analysis based on wavelet packet energy. The results showed that the proposed monitoring method can accurately identify the internal hole defects of concrete filled steel tube.