(6-3) 



where F_ = impulse loading holding capacity 



F = short-term holding capacity 



N = cohesionless soil holding capacity factor adjusted 



for impulse loading 



N = cohesionless soil holding capacity factor 



R = reduction factors for determination of cyclic 

 loading holding capacity 



R = reduction factor for repeated impulse loads 



I f = inertial factor for capacity increase under very 

 rapid loading 



N is the same as that used to determine the short-term holding capa- 

 city (Figure 5-2). N , is an adjusted N based on the impulse loading 

 effect on the friction angle, $. Values for N T can be obtained from 

 Figure 5-2 by using the adjusted friction angle, <t> T , in place of <(). $, 

 is calculated from: 



T I y 1 + (1-1) sin <j> ' 



where (|) = soil impulse adjusted internal angle of friction 



(|> = soil internal angle of friction 



I = influence factor for adjusting soil strength 



Values of I are given in Figure 6-3. R , the cyclic loading reduction 

 factor, is taken as 1 when the impulse load is the first event in an 

 anchor history or when cyclic loading is not expected. Otherwise R is 

 the inverse of the allowable double amplitude cyclic load expressed as a 

 fraction of the short-term holding capacity as determined in paragraph 

 6.2.1. If an impulse is not repeated within 10 minutes, R T = 1. When 

 the loading is expected to be repeated within 10 minutes 



50 



