On the linear stiffness of tension leg platforms

Abstract

The tension leg platform (TLP) is a type of compliant offshore structures generally used for deep water oil exploration. The platforms are moored by very flexible tendons so that surge amplitude can achieve a large value. The platform hull is considered as a rigid body with six DOF. The total restoring stiffness plays a very important role in the TLP dynamic behavior. In present literature inadequate formulations of the stiffness have been used. The problem is to define realistic centre of rotations. The purpose of this paper is to present a consistent formulation of the stiffness matrix, derived from the general solution established for hydroelastic analysis of ship structures, as a specific case. In reality the total TLP stiffness in dynamic analysis consists of hydrostatic hull stiffness (pressure and gravity), and conventional and geometric tendon stiffness. The new stiffness is compared to the known ones, and discrepancies are analyzed and discussed.

The Stability Analysis of Tension-Leg Platforms under Marine Environmental Loads via Altering the Connection Angle of Tension Legs

“…F wind , F hyd , F current , and F Ln are the wind load, hydrodynamic load, current load, and mooring force vector provided by the mooring L n (n = 1, 2, 3...8), respectively. The calculation of the mass matrix and additional mass matrix is referred to in the literature [51], and the total stiffness matrix [52] is expressed as:…”