重力式基礎をもつテンションレグプラットフォームの地震応答

概要

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The Tension Leg Platform (TLP) is a new type of oceanic structure developed for exploiting deep water petroleum. Generally the TLP is moored to the sea-bed foundation by vertical taut tethers. When the TLP is compared with a conventional jacket-type or jack-up-type platform, it has an advantage of low cost when constructing in a deep waters. Since the TLP has been said to be an aseismatic structure, an earthquake load has not been considered as an external force to tethers in design. It is true that the horizontal component of earthquake can be ignored, because the bending rigidity of the tether is nearly zero. However, the vertical seismic force is an important factor to be considered in design, because it is added to pretention of the tether directly. The authors have made theoretical and experimental investigations on the earthquake response of the TLP for years. The purpose of this report is to set up an analysis model for determining the response of TLP at it's connection with the gravity anchor when the TLP is subjected to vertical seismic excitation. As a result of a calculation, the weight of the gravity anchor in water must be more than about two and half times as much as the pretension of tethers.
社団法人日本船舶海洋工学会の論文