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Tension leg platforms are compliant structures for oil extraction in deep water consisting of hull, deck foundation, tendons and risers. The hull is very important part of a TLP from functionality, weight and cost point of views that is made of vertical column and horizontal pontoon with circular and rectangular sections. The hull geometry plays very important rule in optimum action of the structure. The ratio of columns volume to total volume ( ), that is the function of pontoon length ( ), column length ( ), pontoon diameter ( ), column diameter ( ), is an important parameter in structure response against waves loading. In the present research a parametric study has been carried out to investigate the effect of hull geometry on TLP’s responses under wave attack. A wide range of geometric parameters have been considered. A number of models have been set up by changing pontoon length, column length, pontoon diameter and column diameter. In these models the displacement volume, total volume and tendons’ tension were kept constant. Then the structural models were analyzed under wave load using a finite element software. In this paper, results of this parametric study is presented and discussed. Based on these results, appropriate range of dimensionless geometry parameters are proposed for conceptual design of TLPs hull.

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This paper evaluates the hydrodynamic performance of a damaged ISSC TLP which is caused by a tendon disconnection. Performance evaluation of a TLP with a disconnected tendon in a rough sea state is the major aim of this paper. First off, modeling of a platform in a proper sea state is carried out and then after disconnecting one of the tendons, the transient effect on the other tendons is assessed. Also, the steady state forces are validated using analytical results. Additionally, time history of heave and surge accelerations, TLP six degree of freedom motions and also tendon forces are determined in regular waves. In order to assess the hydrodynamic performance of the platform, a numerical simulation is conducted, using multipurpose boundary element software. At last the analysis shows that the modeling of a damaged platform is carried out properly and also the conclusion can be drawn that it is possible to evaluate the performance of a damaged platform in Regular waves.