Structural Response Characteristics of Taut Moored Platforms (continued)

Abstract

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.