광섬유 브래그격자를 이용한 해양플랜트 부유식구조물의 안전진단 연구

Abstract

Offshore plant structures must be secured of structural safety applying real-time monitoring technology about structure respond because they are in a state of very poor ocean conditions. Especially, real-time monitoring system development using Fiber Optical Sensor (FOS) that supplements strain gauge's weakness is expected to strengthen technology and infrastructure of domestic high-tech sensor field.

In this study, Fiber Bragg Grating (FBG), sensors were attached to the scaled model of offshore floating structure, and put in scaled model in the water tank, and then calculated strain after measuring scaled model's wavelength through optical spectrum analyzer. Also Finite element model using ABAQUS was modeled and finite element analysis was conducted to analyze strains. The results of experiment was compared with those of finite element analysis. This study was trying to evaluate the suitability of real-time monitoring of offshore floating structures using FOS. The conclusion can be summarized as follows :

1. This study performed strain measurement of the scaled model using FBG sensor through optical spectrum analyzer. It could confirm behaviors of upper plate of the scaled model because wavelength spectrum according to load application can print out results instantly.

2. In this study, a floating structure using ABAQUS was modeled and finite element analysis was conducted. Through structural analysis results, compression was acted at load application area as the center. And tension was acted from 1/4 part of finite element model to the outermost part. The negative bending moment was presented because both ends of upper plate of scaled model were fixed end support by welding.

3. As the results of the experiment, strains of No.1 and No.6, No.2 and No.5, No.3 and No.4, No.7 and No.10, No.8 and No.9 of scaled model had symmetry with load application area as the center. The error range was very small numerical value within the limits of ±2&micro

ε.

ε were very large numerical value. The error range was measured within ±5&micro

ε.

4. Though comparing experiment results with finite element analysis results, the results of experiment were remarkably consistent with the results of finite element analysis. Although errors(%) in strains of long direction's ends and parts within 10&micro