A series of physical model tests of a semi-braceless floating wind turbine foundation (FOWT) under freak waves was conducted in the present work. The extreme wave run-up phenomenon on the FOWT columns was reported and investigated. The back column exhibits a median wave run-up amplification factor of 1.65 (a 65% rise from the baseline condition), with the maximum recorded value hitting 3.18, marking a 218% amplification compar...