유탄성 해석을 통한 초대형 부유식 구조물의 구조특성 검토

Abstract

Determination of an appropriate structural stiffness of VLFS(Very Large Floating Structure) in initial design is very important not only for safety assessment but for operational effectiveness. Unlike ships and offshore structure to which rule scantling is applicable in initial design of structural member, there is no practical design guide applicable to VLFS yet. Due to lack of sufficient experience in design of VLFS, we have to tackle the initial structural design of VLFS in direct analysis. Since the global structural integrity is much more important than the local structural strength for such huge structures, direct analysis is prerequisite in structural design of VLFS. Furthermore, it is well known that elastic deformation of VLFS influences hydrodynamic loads and responses of the structure. In order to determine initial structural stiffness of pontoon structures, characteristics of wave loads and corresponding structural stress distributions are investigated for various combinations of size and stiffness of the structures. An eigenfunction expansion method is applied to hydroelastic analysis and Kirchhoff plate theory is used for estimation of wave bending moment and stress. It is shown that an optimal structural stiffness can be obtained through a series of parametric study. It is also shown that there exists a critical structural stiffness even if the size of the structure becomes very large when elastic deformation is considered in structural design.