Hull Elements Research Articles

조류와 파랑 중에서의 TLP의 동적구조응답해석

A numerical procedure is described for predicting the dynamic structural responses of tension leg platforms(TLPs) in current and waves. The developed numerical approach is based on a combination of the three dimensional source distribution method and the dynamic structural analysis method, in which the superstructure of the TLPs is assumed to be flexible instead of rigid. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in the dynamic structural analysis. The equations of motion of a whole structure are formulated using element-fixed coordinate systems which have the origin at the nodes of the each hull element and move parallel to a space-fixed coordinate system. The dynamic structural responses of a TLP were analyzed in the case of including the current or not including the one in waves and the effects of current on the TLP were investigated.

Structural Response Characteristics of Taut Moored Platforms (continued)

A linear response analysis method of taut moored platforms subjected to the regular waves was proposed in the previous paper. In this method, the superstructure is assumed a three dimensional elastic frame and each structural member is divided into two kinds of elements; a hull element and a beam element, and each mooring leg is replaced by a mooring element. The hull element is an element for estimating the inertia force, the hydrodynamic force and the hydrostatic restoring force, while the beam element is for estimating the elastic rigidities of the structural members and the mooring element is for estimating the linear restoring force of the mooring leg. The applicability of this analysis method was confirmed by comparison with the experimental results using a so-called footing type of small scale model. Unexpected dynamic responses with a large amount of bending deformation, however, were observed and it was concluded referring the calculated results that these phenomena were due to the structural instability as a truss of the superstructure.In this paper, therefore, another footing type of small scale model whose deck structure is rigid enough to neglect the instability is tested and the experimental results are compared with the calculated ones. Moreover, two kinds of small scale models, which are modified from the model in the previous paper by adding several truss members in order to maintain the structural stability, are analyzed. The structural responses of the superstructure with the sufficient rigidities and their effects on the tension fluctuation of the legs are comprehensively discussed and several important structural response characteristics are induced.

Hull's Elements of Algebra for Beginners. George W. Hull

<i>Hull's Elements of Algebra for Beginners</i>. George W. Hull