3107F.2.2 Component Stiffness

Stiffness that takes into account the stress and deformation levels experienced by the component shall be used. Nonlinear load-deformation relations shall be used to represent the component load-deformation response. However, in lieu of using nonlinear methods to establish the stiffness and moment curvature relation of structural components, the equations of Table 31F-7-3 may be used to approximate the effective elastic stiffness, EI_e, for lateral analyses (see Section 3107F.5 for definition of symbols).

TABLE 31F-7-3
EFFECTIVE ELASTIC STIFFNESS

CONCRETE COMPONENT	EIe/EIg
Reinforced Pile	0.3 + N/(f'cAg)
Pile/Deck Dowel Connection1	0.3 + N/(f'cAg)
Prestressed Pile1	0.6 < EIe/EIg < 0.75
Steel Pile	1.0
Concrete w/Steel Casing
Deck	0.5

1. The pile/deck connection and prestressed pile may also be approximated as one member with an average stiffness of 0.42 EI_e/EI_g (Ferritto et al, 1999 [7.2])
   N = is the axial load level.
   E_s = Young's modulus for steel
   I_s = Moment of inertia for steel section
   E_c = Young's modulus for concrete
   I_c = Moment of inertia for uncracked concrete section