Wave-Induced Pressures and Forces on Deck Slabs near the Free Surface

The hydrodynamic interaction of regular and random waves with a model offshore deck has been investigated in a wave flume. The hydrodynamic pressures and forces on the model as well as its reflection and transmission characteristics are investigated in a dimensionless form. The experiments were carried out for three different clearances $\left(e\right)$ between the still water level and the subface of the model. In order to investigate the effects of relative clearance of the deck ( $e/H$ in case of regular waves and $e/H_s$ in case of random waves), different wave steepnesses ( $H/L$ in case of regular waves and $H_s/L_p$ in case of random waves) were employed by varying wave height $\left(H\right)$ and wavelength $\left(L\right)$ . The effects of the wave steepness, relative clearance of the deck, relative length of the model ( $B/L$ in case of regular waves and $B/L_p$ in case of random waves) on the pressures and forces on the deck slab are investigated with a well controlled experimental program. The variation of the pressures along the length of the model was also investigated in terms of the relative position, $b/B$ . The experimental data was used to derive multivariate predictive equations for uplift (pull-out) forces that could act on actual deck slabs due to waves of various characteristics. It is observed that the maximum nondimensional crest and trough pressures due to random waves occur for a relative clearance of $e/H_s=0.3$ .