Effect of Pretension on Triangular Tension Leg Platform (TLP) Responses

Abstract. TLP (Tension Leg Platform) is a type of column-stabilized moored platform where the buoyancy exceeds its weight and thus the vertical equilibrium of the platform requires a system of pre-tensioned tethers held in tension connecting the upper structure to a foundation on the sea bed. A typical TLP is four-legged, while triangular TLP is three-legged. This study was conducted to determine the effect of variation of pretension on the dynamic responses of a triangular TLP. A dynamic analysis was conducted in frequency domain using Linear Airy Wave theory and Morison equation to analyze the responses of triangular TLP subjected to a random wave generated using Pierson-Moskowitz spectrum. Experimental model tests for validating the analytical results were conducted in the wave tank of the Offshore Laboratory at UTP. The results indicated that the responses were inversely proportional to the tether pretension.