F = A y L D N (0.84 + 0.16 B/L) (5-2) 



st D q 



where B = 0.75 m (2.5 ft) 



L = 1.5 m (5 ft) 



A = B x L = 1.13 m 3 (12.2 ft 2 ) 



Y b = 880 kg/m 3 ( 55 lb/ ft 2 ) 



D = 4.8 m (15.7 ft) 



D/B = 6.3 



N = 18 (Figure 5-2) 



Therefore , 



F ^ = 1.13(880)(4.8)(18)[0.84 + 0.16(0.75/1.5)] 

 st 



= 775 kN (174,000 lb) 



No distinction is made between long- and short-term static capacity in 

 sand ; therefore : 



F lfc = 775 kN (174,000 lb) 



Applying the factor of safety recommended when soil properties are well 

 known , 



Allowable static load = 775/2 = 388 kN (87,000 lb) 



7.2.6 Cyclic Loading 



7.2.6.1 Strength Loss During Cylic Loading . Following the 



procedures of paragraph 6.2.1, t , is found from Figure 6-5 to be 

 about 50 seconds for the permeability and anchor width given. With an 

 8-second period, about seven cycles are applied in the period t ,. 



67 



