7.324 Wall of Low Height . It is often not economically feasible to 

 design a structure to provide a nonovertopping condition by the design 

 wave. Consequently, it is necessary to evaluate the force on a structure 

 where the crest of the design clapotis is above the top of the wall as 

 shown in Figure 7-71, The resulting pressure distribution is shown by 

 the shaded area, and the force resulting from it is F' . The magnitude of 

 F' is proportional to F, the force that would act against the wall if 

 it extended up to the crest of the clapotis (the force determined from 

 Figures 7-66 or 7-69) . The relationship between F' and F is given by 



F' = TfF , 

 where r^. is a force reduction factor given by 



and 



y \ y 



Tr = 1.0 



/hen 



when 



- < 1.0 , 



y 



t > 1.0 , 



y 



(7-69) 



(7-70) 



where b and y are defined in Figure 7-71. The relationship between 

 r^ and b/y is shown in Figure 7-72. 



•Crest of Clapotis 



\ 



wd 



Figure 7-71. Wall of Low Height - Pressure Distribution 

 Similarly, the reduced moment about point A is given by 

 M' = r M, 



where the moment reduction factor r^ is given by 



and 



-='7-7 



1.0 



irhen 



< 1.0 , 



> 1.0 1 



(7-71) 



(7-72) 



7-139 



