(1)

Determine the design load Rd for a given pile in pounds.

(2)

this:

(a)

This value can be given either in the design plans, or computed by the

methods referred to in Paragraph 2-11b.

(b)

The design load Rd can be multiplied by a factor of safety, according to the

formula

Ru = N Rd

where

Ru = ultimate pile resistance, pounds

N = factor of safety

= 2.0 when static load tests are required

= 2.5 when the pile driving analyzer and wave equation analysis are

required

= 3.0 when only the wave equation analysis is required. (if a factor of

safety has been established for the piles elsewhere, then use that

value.)

If values from both (a) and (b) are available, then use the greater of the two.

(3)

Divide the ultimate resistance value by the pile area using the formula

Su = Ru/Ap

where

Su = ultimate pile resistance per unit area, psi. This

value should not fall below 900 psi with concrete

piles or 9,000 psi with steel piles for subsequent

computational purposes

As = pile cross-sectional area, square inches

(4)

Compute the minimum rated striking energy for the pile hammer for the particular

pile at 10 blows per inch. The formula used depends upon whether the pile is steel or

concrete.

Er 10BPI = As Su / (21.36 e(-Su/3690)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . Concrete Piles

Er 10BPI = As Su1.62/5400 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel Piles

where

Er 10BPI =

minimum hammer rated striking energy at 10 blows per inch of

resistance, foot-pounds

Figure 2-1b. Preliminary Method for Sizing Hammers for Concrete and Steel Piles, Metric Units

(after Florida DOT Specification, Section 455).

2-7

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