*************** EXAMPLE PROBLEM 20************** 



GIVEN : A design wave with height H = 3.0 m (9.8 ft) and period T = 10 s 

 acts on a vertical circular pile with a diameter D = 0.3 m (1 ft) in 

 depth d = 4.5 m (14.8 ft) . Assume that C = 2.0 , C = 0.7, and the 

 density of seawater p = 1025.2 kg/m"^ (1.99 slugs/ft-^) . (Selection of 



C,, and C_ is discussed in Section III, I.e.) 



M D 



FIND: The maximum total horizontal force and the maximum total moment around 



the mud line of the pile. 

 SOLUTION: Calculate 



4.5 



= 0.0046 



2 2 



gT (9.8) (10) 



and enter Figure 7-75 to the breaking limit curve and read 



H 



b 



= 0.0034 



2 

 gT 



Therefore, 



b 

 and 



H = 0.0034 gT = 0.00357(9.8) (10) = 3.3 m (10.8 ft) 



iL= 3^= 91 

 H 3.3 ^'^^ 

 b 



2 _ 



From Figures 7-71 and 7-72, using d/gT"^ = 0.0046 and H = 0.91 H, 

 interpolating between curves H = H, and H = 3/4 H, , find: 



K. = 0.38 



K^ = 0.71 

 Dm 



From equation 7-37 : 



.2 



ttD 



.2 



F. = (2) (1025.2) (9.8) 1^°^ (3.0) (0.38) = 1619 N (364 lb) 

 ^m 4 



and from equation (7-38): 



F = C 4- Pg DH^K 



DM D ^ DM 



7-127 



