Experimental Investigations of Acceleration on Slender Cylindrical Member under Breaking Waves

Abstract

Many of the coastal and offshore structures consist of slender cylindrical member as the fundamental component. Since the structural damages and failures are catastrophic under wave impact, it is essential to understand the influence of breaking wave impact on the structural members. Past literature dictates that the magnitude of impact pressures is of the order of ten times more than the non breaking wave induced pressure. The standard codal provisions for the structural design of those members under breaking wave impact are scarce. In the present study, an experimental investigation has been carried out to measure the response of the slender vertical cylinder under breaking waves. Acceleration measurements were made under the incidence of breaking waves of different intensities varying from Plunging to Spilling. Deflections are found out from the measured acceleration. The maximum acceleration observed under severe plunging event is 0.5 times that of moderate plunging event, the deflection induced by the moderate plunging is two order higher than that of severe plunging. Acceleration is maximum not only above still water level (SWL) but also lies in the impact zone. Hence moderate plunging events with higher impulse and larger pressure rise time is crucial in the design of offshore and coastal structural member under breaking wave impact load.