NONLINEAR COUPLED RESPONSE OF OFFSHORE TENSION LEG PLATFORMS TO REGULAR WAVE-FORCES

Among the compliant platforms, the tension leg platform (TLP) is a ver tically moored structure with excess buoyancy. The TLP is designed to behave in the same way as any other moored structure in horizontal pla ne, at the same time inheriting the stiffness of a fixed platform in t he vertical plane. Dynamic response analysis of a TLP to deterministic first order wave forces is presented, considering coupling between th e degrees-of-freedom surge, sway, heave, roll, pitch and yaw. The anal ysis considers nonlinearities produced due to changes in cable tension and due to nonlinear hydrodynamic drag forces. The wave forces on the elements of the pontoon structure are calculated using Airy's wave th eory and Morison's equation ignoring diffraction effects. The nonlinea r equation of motion is solved in the time domain by Newmark's beta in tegration scheme. The effects of different parameters that influence t he response of the TLP are then investigated. (C) 1997 Elsevier Scienc e Ltd.