167 If
ππ
ππ
β€ ππ
ππππ
ππ
ππ
= Equation 11-40) In which, for HP-sections
about the weak axis ππ
ππ
= Equation 11-41) If th
ππ
ππππ
< ππ
ππ
β€ ππ
ππππ
e nominal flexural resistance about the weak axis is:
ππ
ππ
= [1 β οΏ½1 β
ππ
π¦π¦
ππ
π¦π¦
οΏ½
β
β
β
β ππ
ππ
β ππ
ππππ
0.45οΏ½πΈπΈ
π π π‘π‘
πΉπΉ
π¦π¦ππ
β
β
β
β
]ππ
π¦π¦ππ
ππ
π¦π¦
(Equation 11-42)
Where:
ππ
ππ
= Nominal flexural resistance (kip-in).
ππ
ππ
= Plastic moment about the weak axis (kip-in).
ππ
π¦π¦
= Elastic section modulus about weak axis (in
3
).
ππ
π¦π¦
= Plastic section modulus about weak axis (in
3
).
ππ
ππ
= Slenderness ratio for flange (Eq. 11-37, dimensionless).
ππ
ππππ
= Limiting slenderness ratio for a compact flange (Eq. 11-38, dimensionless).
πΈπΈ
π π
t
= Elastic modulus of steel (ksi).
πΉπΉ
π¦π¦
= Yield stress of steel (ksi).
πΉπΉ
π¦π¦ππ
= Minimum yield strength of lower strength flange (ksi).
11.4.5.2 Steel Pipe Piles Step 1: Check diameter to thickness ratio If the diameter to thickness ratio is sufficiently large, local buckling limits flexural resistance. To inspect whether the plastic moment or local buckling will
govern flexural resistance, Eq. 11-43 should be applied. If Eq. 11-43 is satisfied, the plastic moment will yield the steel pile and Step a should follow. Conversely, local buckling will limit flexural resistance if Eq. 11-43
is not satisfied, and therefore Step b should follow.
π·π·
π‘π‘ β€ Equation 11-43) Where
π·π· = Outside diameter of pipe (in.
π‘π‘ = Pipe thickness int Elastic modulus of steel (ksi). y = Yield strength of steel (ksi).
