| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 102 === Bridge scour is the major cause for many bridge failures and damage to piers and abutments. Scour is not easily discernible since it is hidden under the channel flow. Over the years, a number of sensors have been developed for detection of scour depth. Development, testing, and small-scale field implementation of a new and simple type of scour sensor in a flume are described in this study. The proposed sensor uses a MEMS accelerometer and attached to a reed which is fixed on the considered pier. The scour depth detection concept is based on observing the amplitude of acceleration time history whether reached the threshold or not. In addition, the relationship between the fundamental frequency of the pier and the scour depth is also discussed. The fundamental frequency of the pier is obtained from the acceleration time history, acquisition by the accelerometer on the top of the pier, using Hilbert-Huang Transfer (HHT) method. Experiment results demonstrate that the fundamental frequency decreased with increasing the scour depth. Furthermore, the proposed sensor could be used as a water-level indicator, scour depth sensor, and anemometer.
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