Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities

Step-by-Step Procedure for Nominal Flexural Resistance

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Soldier Rev B

Step 2: Determine the nominal axial compressive resistance, P

11.5.2 Step-by-Step Procedure for Nominal Flexural Resistance
Step 1: Determine the normalized column slenderness factor,
𝝀𝝀.
The normalized column slenderness factor is to be evaluated using the following equation. However, if the pile is fully embedded, λ maybe taken as 0 (AASHTO 2014).
𝜆𝜆 = Equation 11-55) In which
𝐹𝐹
𝑒𝑒
= 𝐹𝐹
𝑦𝑦
+ 𝐶𝐶
1
𝐹𝐹
𝑦𝑦𝑐𝑐
�
𝐴𝐴
𝑠𝑠𝑡𝑡𝑐𝑐
𝐴𝐴
𝑠𝑠𝑡𝑡
� + 𝐶𝐶
2
𝑓𝑓
𝑐𝑐
′
�
𝐴𝐴
𝑐𝑐
𝐴𝐴
𝑠𝑠𝑡𝑡
� Equation 11-56)
𝐸𝐸
𝑒𝑒
= 𝐸𝐸
𝑠𝑠𝑡𝑡
�1 + �
𝐶𝐶
3
𝑚𝑚 � �
𝐴𝐴
𝑐𝑐
𝐴𝐴
𝑠𝑠𝑡𝑡
�� Equation 11-57)
𝑚𝑚 = Equation 11-59) Where
λ = Normalized column slenderness factor. st Cross sectional area of steel (inc Cross sectional area of concrete (instr Cross sectional area of longitudinal reinforcing steel (in.
𝐾𝐾 = Effective length factor
𝑙𝑙 = Unbraced length in the plane of buckling (in. rs Radius of gyration about axis normal to plane of buckling (in.
𝐹𝐹
𝑒𝑒
= Nominal compressive resistance of composite section (ksi).
𝐹𝐹
𝑦𝑦
= Yield stress of steel (ksi). yr Yield stress of reinforcing steel (ksi). c Concrete compressive strength at 28 days, unless otherwise specified (ksi).
𝐸𝐸
𝑒𝑒
= Modified elastic modulus of steel for composite column (ksi).

174
E
t
= Elastic modulus of steel (ksi).
E
c
= Elastic modulus of concrete (ksi).
C
1
= Composite column constant 1 (1.00 for concrete filled pipes.
C
2
= Composite column constant 2 (0.85 for concrete filled pipes.
C
3
= Composite column constant 3 (0.40 for concrete filled pipes.
Step 2: Determine the nominal axial compressive resistance, P

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