WAVE FORCES ON A PLATFORM WITH A RIBBED BOTTOM

Abstract

Observation of hurricane damage along the Mississippi Gulf Coast has stimulated studies of wave action on structures which permit the waves to pass beneath the floor or bottom surface. This paper reports a laboratory study which compares relative drag and lift forces on a structure with a plane, horizontal bottom surface to those on a structure with a ribbed bottom surface, for various conditions of relative wave height and relative clearance of the structure above the stillwater surface. Also, the effects of relative depth of ribs, relative spacing of ribs, and end webs or diaphragms are noted. The study was limited to the condition for which the bottom ribs were transverse to the general direction of wave motion. The results, which are presented in graphical form, clearly show the effects of the ribs.