Design pile foundations such that the pile penetration after the design scour events satisfies the required nominal axial and lateral resistance. At pile locations where scour is predicted, the nominal axial resistance of the material lost due to scour should be determined using a static analysis. The piles will need to be driven to the required nominal axial resistance plus this nominal skin friction resistance that will be lost due to scour.

∑ηiγiQ

i

≤ ϕR

n

Nominal resistance needed (R

n

) in the static final condition after compensating for design scour must be greater than the factored loads (∑ηiγiQi). Include an additional resistance factor (ϕdyn) for the driving resistance checks during construction based on the dynamic method used:

R

n

≥ (∑ηiγiQ

i

) / ϕdyn

Normal pile driving resistance achieved during construction (R

ndr

) includes the skin friction (side resistance) contribution that would be lost in the scour zone:

R

ndr

= R

n

+ R

scour

R

ndr

= Nominal (ultimate) resistance during pile driving, dynamically evaluated

R

n

= Nominal (ultimate) resistance needed in the final static condition

R

scour

= Unfactored skin friction which must be overcome during driving in scour zone (kips)

Q

p

= (∑ηiγiQi) = factored load per pile (kips)

ϕdyn = resistance factor

D

est.

= estimated pile length needed to obtain desired nominal resistance per pile (ft)