The relationship between r^^, and b/y is also shown in Figure 7-72. 

 Equations 7-69 through 7-72 are valid, when either the wave crest or wave 

 trough are at the structure, provided the correct value of y is used. 



************** FXAMPLE PROBLEM *************** 

 GIVEN: 



(a) Wall height, b = 16.0 feet. 



(b) Incident wave height, H^ = 5.0 feet. 



(c) Depth at structure toe, d = 10.0 feet. 



(d) Wave period, 



T = 6 sec. (minimum), T = 10 sec. (maximum) 



FIND : Determine the reduced wave force and moment on the given vertical 

 wall. 



SOLUTION : From the example problems in Section 7.323, 



y^ = 18.50 ft. 



y^ = 8.50 ft. 

 Compute b/y for each case 



b 16.0 



(T = 6 sec.) 



= 0.865, 

 y^ 18.50 



b 16.0 



— = = 1.88 > l.O. 



y^ 8.50 



(T = 6 sec.) 



Entering Figure 7-72 with the computed value of b/y, determine the 

 values of r^. and r from the appropriate curve. For the wave with 

 T = 6 sec, 



— = 0.865 ; therefore, tr = 0.981 ; r_ = 0.950, 



Yc f m > 



and 



b 

 — > 1.0 ; therefore, Tr = 1.0 ; r_ -= 1.0 



y^ / m 



7-141 



