Multidirectional Wave Loads on Vertical Breakwaters

Measurement of Wave Pressure on Perforated Caisson Wall Under Oblique Wave Incidence

“…The tendency of higher wave loading under more oblique wave conditions was also confirmed from the results of direct measurement of wave loading by using the load cells. Similar trend as in this study was reported by Franco et al (1996), who found general increase of the measured force on solid vertical wall with increasing wave obliquity.…”

“…In the range of the present experiment, the value of this factor will decline from 1 to 0.85 when  is increasing from 0° to 45°. Similar results as in this study were reported by Franco et al (1996), who showed that horizontal force on the solid caisson does not decay with increasing obliquity of the mean wave direction, originally assumed by Goda's formula. In contrast, relatively good agreement with Goda's formula for oblque waves under both breaking and non-breaking conditions was observed in the experiment of Frigaard et al (1998).…”

“…Concerning this issue, several researchers have investigated influence of wave obliquity on the wave loading on solid vertical breakwaters (Franco et al, 1996;Allsop & Calabrese, 1998;Frigaard et al, 1998). They assessed the effects of wave obliquity and multi-directionality on the hydraulic response of non-perforated caisson walls.…”

Impact Loadings on Vertical Walls in Directional Seas

“…The predictions do not take account of caisson length, L c , so measurements used in this analysis were those of F h i/25o(0), thus giving three sets of measurements representative of wave forces over a narrow vertical strip, Forces for long-crested normal waves in Figure 6 have been non-dimensionalised as Fhi/250 /pgh/, and plotted against relative wave height H s /h s . Summary results from the 3-d tests by Franco et al (1996), are included, for which EJh s = 0.20. These forces are very similar to those measured here for the lower values of H s /h s where there are no impacts, only pulsating loads.…”

“…Methods to evaluate wave forces under oblique and/or short-crested waves have been suggested by the empirical methods of Goda (1985) or theoretical methods of Battjes (1982). Battjes' method estimates wave force reduction coefficients in relation to: angle of attack, p; directional dispersion index, n; and relative length of caisson or wall element L c /L, where the element length is L c and wavelength is L. Experiments by Franco et al (1996), measured effects of long-and short-crested waves with P < 60° and standard deviation of spreading < 30°, but did not record impact loads.…”