EI 02G001
CEMP-E
01 July 1997
(5)
Recompute the ultimate unit pile resistance using the formula
Su' = 3 Rd/As
where
Su' =
ultimate pile resistance per unit area for 20 BPI case, psi. This value
should not fall below 900 psi with concrete piles or 9,000 psi with
steel piles for subsequent computational purposes
(6)
Compute the minimum rated striking energy for the pile hammer for the particular
pile at 20 blows per inch. The formula used depends upon whether the pile is steel or
concrete.
Er 20BPI = Su' As/(30.72 e(-Su'/3333)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . Concrete Piles
Er 20BPI = As Su'1.68/13569 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel Piles
where
Er 20BPI =
minimum hammer rated striking energy at 20 blows per inch of
resistance, foot-pound
(7)
The minimum rated striking energy for the hammer is the greater of Er 10BPI and Er
.
20BPI
(8)
Compute the minimum ram weight. Having computed the minimum rated striking
energy for the hammer, one or more hammers can be selected as possible candidates
for driving the pile. The equivalent stroke should be then computed by the equation
Seq = Er/Ws
where
Seq =
equivalent stroke, feet. This should not exceed 8 feet for subsequent
Er = rated striking energy of the hammer, foot-pounds
Ws = ram weight of the hammer, pound
(9)
The minimum ram weight for each hammer can be computed for concrete and
steel piles by the equation
Wsmin = 45.5 As/(Seq) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Concrete Piles
Wsmin = 415 As/(Seq) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel Piles
where
Wsmin = minimum ram weight, pounds
A hammer should be rejected if its ram weight is less than the minimum ram weight, and
other hammers should be considered until one has been selected with a sufficiently
large ram.
Figure 2-1b. (Concluded)
2-8
Previous Page
