For example, if C « 2 C and a design wave corresponding to H/% = 

 0.75 is assumed, the ratio ^-irJ^TM ""^^ ^^ written (using Figures 7-71 and 

 7-72) as 



„ , 1.25 — (shallow-water waves) 



x,m 



^Dm I ■- ^c D /. , s (7-55) 



' 5.35 — (deepwater waves) 

 n 



Since D/H will generally be smaller than unity for a design wave, the 

 inertia-force component will be much smaller than the drag-force component for 

 shallow-water waves and the two force components will be of comparable magni- 

 tude only for deepwater waves. 



f . Example Problem 27 and Discussion of Choice of a Safety Factor . 



*************** EXAMPLE PROBLEM 27************** 



GIVEN : A design wave, with height H = 10.0 m (32.8 ft) and period T = 12 

 s , acts on a pile with diameter D = 1.25 m (4.1 ft) in water of depth d 

 = 26 m (85 ft) . 



FIND : The wave force on the pile. 



SOLUTION ; Compute 



H 10.0 



gT (9.8) (12) 



and 



d 26 



= 0.0071 



= 0.0184 



2 2 



gT (9.8) (12) 



From Figure 7-68, for d/gT^ = 0.0184 , 



o 



and 



gT (9.8) (12) 



L = 0.76 L = 0.76 = 0.76 = 170.7 m (559.9 ft) 



A o 2-n iTi 



From Figure 7-69 for d/gT^ = 0.0184 , 



n 



S- = 0.68 



H 



7-146 



