“…Examples in the offshore literature include: separate treatment of WF and LF motions combined via Turksta's rule [9], use of parametric response surfaces to interpolate required response values [9,10], a simplified [11,12] or inaccurately assumed [13,14] distribution of the independent LF motion extremes, or simplified analysis of the response peaks based on return-period ideas [15]. Although efficient, mathematically rigorous combination of WF and LF response is possible [16,17], in the offshore literature this is usually restricted to time domain simulation.…”