Long Term Failure Probability Calculation Method Applied to Riser Design

A time efficient methodology is described to evaluate the non linear extreme response of a riser connected to a FPSO subjected to wave induced loads in a stationary sea state. It is extended to cover all sea states and thus to assess the long term failure probability of the riser. The short term procedure is based on a classic time variant reliability method. It uses an approximation of the mean outcrossing rate, which is computed with the time invariant reliability method FORM (First Order Reliability Method).