Experimental Study on Ultrasonic Tomographic Method to Detect Compactness of Concrete filled Steel Tube

Abstract When the concrete filled steel tube member is poured, due to the large volume, the internal concrete is difficult to vibrate, easy to produce defects, not easy to observe, and the internal defects will have a non-negligible impact on its mechanical properties, therefore, it is particularly important to detect the internal defects of the concrete filled steel tube column. In this paper, the internal defects of CFST are studied based on the principle that acoustic wave propagates along the shortest acoustic path in CFST. For square concrete-filled steel tubular column, when the measurement method is adopted, the theoretical sound time calculation and sound velocity distribution map imaging are carried out for different measurement point densities. It is found that the defect identification effect is better when the number of measurement points is 5.For circular concrete-filled steel tubular column, when the measurement point spacing is determined to be 30° arc length, the measurement point arrangement method in the specification cannot be combined with CT imaging method, so the measurement point arrangement method of one-point emission and five-point receiving is proposed, and it is found that it has good identification effect on internal defects.