Comparison of loads predicted using "newwave" and other wave models with measurements on the tern structure

Global wave loads measured on the Tern platform durlng a very severe storm have been compared wrth predlctrons made on the basls of three drfferent models for wave klnematlcs The flrst IS the "Newwave" theory, a broadbanded, probabllrstlc-based model for the extreme waves of a random seastate The second model lnvolves complex tlme-domarn slmulatlon of random dlrectlonal seas Both these theorles are used wrth the Morlson equatron and reallstlc force coefflclents to predicgt lobal forces The thlrd wave model IS the Stokes flfth-order theory wrth artrfrcral values for the force coeffrclents, as used In conventional deslgn practlce Both the Newwave theory and the random dlrectronal s~mulat~onlse ad to predicted base shear forces that are comparable to the measured values over a wlde range If non-hear effects In the ocean surface are accounted for, then the Newwave theory predlcts the base shear generated by the largest wave of the storm wlth a very hlgh degree of accuracy In contrast, calculat~ons based on the Stokes klnematlcs of conventronal deslgn practlce overpredlct the measured loads over the whole range studred It appears that Newwave IS the most sultable available wave theory for routlne use In the deslgn and analysls of structures such as Tern.