2025 Volume 4 Issue 1 Pages 318-327
Ultrasonic was applied to investigate the grout filling of a PC post-tensioned T-girder bridge constructed in the 1960s. The error rate between the web thickness in the T-girder estimated by the ultrasonic method and the design web thickness was used as the judgment index for grout filling. A new estimation method using the multiple reflection frequency of ultrasonic longitudinal waves was proposed for web thickness estimation. In the proposed method, two types of speeds were applied for web thickness estimation: (1) wave speed obtained by transmission method, (2) wave speed a variation of about ±10% of the transmission method speed is allowed. The judgement criteria for grout filling were an error rate of less than 10% in the former case and less than 1% in the latter case. As a result, it is found that the measuring areas where the grout filling criterion is exceeded by ultrasonic method correspond to the areas where the grout filling is insufficient by the X-ray transmission method. In addition, it is shown that the proposed method can figure out the grout filling condition as an error rate distribution in T-girder.
