가거초 해양과학기지 구조물 동특성을 이용한 해석모델 개선

Model Updating for Gageocho Ocean Research Station Structure Using Structural Dynamic Characteristics

In order to study oceanic environmental changes affecting the climate change and global warming, the Korean government supports the construction and operation of several ocean research stations (ORS) such as Ieodo ORS, Gageocho ORS and Sochengcho ORS in remote area. Among these ORSs, the Gageocho ORS was directly attacked by Typhoon Muifa in 2011 and its structural members were severely damaged. After this structural failure, the Gageocho ORS was rehabilitated and instrumented with dynamic measurement system. In this study, the preliminary finite element (FE) model of the repaired Gageocho ORS was updated using the natural frequencies estimated by the measurement. Mass reallocation method and the pattern search method were utilized for the FE model updating. The former was applied to rationally redistribute the lumped mass ignored in static analysis in platform and the latter was used to obtain the optimal values for mass redistribution as well as other material properties such as an elastic modulus of concrete. This significantly reduced the errors of natural frequencies for the estimated values by under 1% from larger than 15% in the preliminary FE model. The updated baseline FE model can be useful for further performance analysis including reliability analysis, wave and seismic analysis, and also for structural health monitoring.