The dynamic component of force from equation (7-106) is, 



v3 



_ ^^b^g / ^1 \ _ 10,047 (3.3)(2.3) /, 12 V _ „ 



= 27.8 kN/m 



905 lb/ft) 



and the moment from equation (7-107) is 



^ ^ ^ ^ (6.500^) 



The hydrostatic force and moment from equations (7-108) and (7-109) are, 

 R^ = !^ L !iY . IOM7U.3)' L _ nV . 21.5 W« (1.475 lb/ft) 



2, 



and 



M =!!^/'l_^^ = 10,047 (2.3)^ /^l -i^V =14.9^^^ 

 "s 6 l^ X i 6 I ^ 120 I m 



^ ^ ^ ^ (3.400^ ) 



Total force and moment are 



R^ = I^ + I^ = 27.8 + 21.5 = 49.3 kN/m (3,400 lb/ft) 



1^ = 1^ + >^ = 28.8 + 14.9 = 43.7 ^:^ (9,800 ^^'^^ ) 

 *************************************** 



5. Effect of Angle of Wave Approach . 



When breaking or broken waves strike the vertical face of a structure such 

 as a groin, bulkhead, seawall, or breakwater at an oblique angle, the dynamia 

 component of the pressure or force will be less than for breaking or broken 

 waves that strike perpendicular to the structure face. The force may be 

 reduced by the equation, 



R' = R sin^a (7-112) 



where a is the angle between the axis of the structure and the direction of 

 wave advance, R' is the reduced dynamic component of force, and R is the 

 dynamic force that would occur if the wave hit perpendicular to the struc- 

 ture. The development of equation (7-112) is given in Figure 7-106. Force 

 reduction by equation (7-112) should be applied only to the dynamic wave- force 

 component of breaking or broken waves and should not be applied to the 



7-198 



