해양구조물의 동특성 평가 및 건전성 모니터링

Abstract

Previous long-term measurements of the Uldolmok tidal current power plant showed that the structure’s natural frequencies fluctuate with a constant cycle—i.e., twice a day with changes in tidal height and tidal current velocity. This study aims to improve structural health monitoring (SHM) techniques for offshore structures under a harsh tidal environment like the Uldolmok Strait. In this study, lab-scale experiments on a simplified offshore structure as a lab-scale test structure were conducted in a circulating water channel to thoroughly investigate the causes of fluctuation of the natural frequencies and to validate the displacement estimation method using multimetric data fusion. To this end, the numerical study was additionally carried out on the simplified offshore structure with damage scenarios, and the corresponding change in the natural frequency was analyzed to support the experimental results. In conclusion, (1) the damage that occurred at the foundation resulted in a more significant change in natural frequencies compared with the effect of added mass

(3) displacement estimation using data fusion was valid compared with the reference displacement using the vision-based method.

(2) the proposed damage index was able to indicate an approximate level of damage and the nonlinearity of the lab-scale test structure

moreover, the structural system became nonlinear when the damage was severe