8. Design of Coastal Structures
251
Fig. 8.15 Définition sketch of Goda’s wave induced pressure under crest.
8.4 Goda’s Method of Breaking Wave Force (1974)
(CEM Table VI-5-53, p. VI-5-139)
It is based on model tests and design against the single largest wave force
in design sea state is considered. It also uses the highest wave in a wave
group. The design wave height, H design is estimated at a distance of 5 x Hs
seaward of breakwater (Hdesign — 1.8HS). It is later modified to incorporate
random wave breaking model and assumes trapezoidal shape for pressure
distribution along front wall of caisson imbedded into the rubble mound.
The uplift pressure distribution is assumed to be triangular.
Hmax should be based on Goda’s random wave breaking model, and
Hmax = 1-8 H s is recommended. Elévation to which wave pressure is
exerted,
p* = 0.75(1 + cos/3)2Tmax
(8.24)
in which, /3 — direction of waves with respect to breakwater normal (for
waves approacb’ng normal to breakwater, (3 = 0)
Pressure on front of vertical wall,
Pi = 0.5(1 + cos/?)(ai + Q!2 cos2/3)7Æmax
for rj* > hc
for rj* < hc
P3 = a3Pi