3.2 

 3.0 

 2.8 





















































































































































medium-coarse sands 







































0l = sin 



/ I sin 



\ 



2.6 

 2.4 

 2.2 

 2.0 

 1.8 

 1.6 

 1.4 

 1 f 





1 



























































































































































































































































































--,„ 



































































;; 



^^ 













































1 

























" :r ^ r ^ 



^ 





~ 



~ 



- 

























0.01 



0.1 



1.0 10.0 



Load Duration (sees) 



100.0 



1000.0 



Figure 6-3. Strength influence factors for cohesionless soils (from 

 Douglas, 1978). 



-0.116 f 



Rj = 2 e 



where f = number of impulses in 10 minutes 



(6-5) 



I„ is used only when the impulse load duration is expected to be 0.01 

 second or less. When this condition is met, values for the inertial 

 factor can be found in Figure 6-2. 



6.2 CYCLIC LOADING 



Cyclic loads are loads of less than 1-minute duration applied in a 

 repetitive manner. They result primarily from wave-induced forces, 

 cable strumming, and earthquake loading. Waves induce cyclic loads by 



51 



