Question

A precast concrete pile (14 in. X 14 in.) in cross section is driven by a hammer. If the maximum rated hammer energy is 400 kip.in, the hammer efficiency is 70%, weight of ram is 4.000 Kg. the pile length is 25 m, Coefficient of restitution is 0.35, weight of pile cap is 300 Kg, and E, is 480*100 lb ft number of blows for last 1 in. of penetration is 9. and FS is 5. Calculate the allowable pile capacity using the modified EN formula.

Answer 1

liven data: Precast concrete pile 14 in x 14 is hammer rating the 400 kip-in = 400x 10 lb in hammer efficiency, eu= 70% weight of eam, Ww= 4000kg = 8818.49 16 length of pile, L= 25m = 82.021ft Coefficient of restitution, A= 0.35 weight of pile cap, We = 300kg = 661.387 Ep = 480x loo lb/ft² No. of blows, N=9 Set no, s= lin= o.lll in 1 blow fs= s we know that unit weight of precast concrete, Ve= 150 lb/ft² * wt of pile section = 1508 14 x 14 x 2 W=204.167x82.021 W = 16745.95 16 - weight of pile , wp= W+ We 12 12

- Wę twp J 2 wp= 16745.95+661.387 Wp = 17407.34 lb Now According of Modified ENR equation: Pez (1.25 ene Eu (wa tanong 041.35* O * 2x400x 10970018:49 (1.25% 0.7x400x 108] 8818.49+ 0.35 x 174073 10.1!! +0.1 J 8818.49 +17407.3 Pu = 692637.8 16 r where: 1 Pu= ultimate pile lu= 692.64 kip T capacity le= o.lunch J .: Allowable pile capacity, Poze pe = 692064 = 138.53 kips 692.69 = 138.53 kips Therefore allowable file capacity is 13853 kips