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Tension leg platforms (TLPs) are well-known structures for oil exploitation in deep water. Tethers are one of the most important component of these structures. Nonlinear response of TLP tethers under the combined action of wave and current was investigated in the present issue. Both the quadratic damping due to fluid resistance and parametric excitation due to top tension variations are included in the mathematical model. Only the vortex-induced transverse oscillations under lock on conditions were examined. A fourth order runge-kutta method was used to solve the equations of motion of tendons. The effects of surge motion coupling on the heave motion, the effects of tendon's oscillation on... 

The primary objective of this research is probabilistic quantification of the fatigue life of tension-leg platforms (TLP) using reliability methods. The need for such methods stems from the significant uncertainty in the loads exerted on offshore structures. The scope of this paper is limited to the study of fatigue in TLP tendons. For this purpose, nonlinear force time history response of the TLP tendon under random wave loads is computed and the damage due to fatigue is estimated in accordance with the Palmgren-Miners rule. Assuming a Rayleigh distribution for stress variation and eight different sea states, the ultimate fatigue damage is computed by accumulating the damage over all...