Stochastic Response of Intact and a Removed Tendon Tension Leg Platform to Random Wave and Current Forces

Abstract

This work analysed the dynamic response of intact and a removed tendon tension leg platform (TLP) in simultaneous action of random wave and current loads in normal and less severe environments. Two different sea states of extreme severe sea state but less probable and less severe state and most probable are considered in this study. The artificial random wave is simulated by Monte Carlo simulation using Pierson–Moskowitz spectrum. Wave diffraction effect is not considered since the ratio of characteristic dimension to wavelength is less than limit. The coupling in all degree of freedoms and various degrees of nonlinear effects is considered. The inertia, mass, damping matrices of equation of motion and hydrodynamic force vector are formulated and solved numerically using Newmark integration scheme. The statistical results show that removal of one tendon increases surge and tendon tension values, while heave and pitch are not adversely affected in both environments. The response values of the TLP in extreme severe sea state are quite higher compared to less severe sea state. The percentage increase in all degree of freedoms and tendon tension is <5 % when one tendon is removed as compared to intact tendon TLP. It could be concluded that maximum and minimum tension in tendon constraints is equally passed by the TLP tendons.