RELIABILITY ASSESSMENT OF TENSION LEG PLATFORM TETHERS UNDER NONLINEARLY COUPLED LOADING

This paper deals with the design of TLP tethers under wind and wave in duced loading using reliability analysis. Two modes of tether failure are considered, namely (1) the maximum life time tension exceeding yie ld stress and (2) the minimum life time tension less than zero. A dyna mic response analysis is carried out considering nonlinearities due to drag, variable submergence, variable tether tension, wind induced loa ding and large displacements. Various degrees of freedom are considere d to be coupled. Reliability assessment is carried out by Monte Carlo failure analysis using simulation techniques. A methodology is develop ed for finding the expected life of the platform based on the results of reliability study. Finally, a design approach is established involv ing the determination of optimum yield stress in tethers. (C) 1996 Els evier Science Limited.