Impact of Plastic Hinge Properties on Capacity Curve of Reinforced Concrete Bridges

Table 1

Curvature limit states.

Failure criteria	Plastic curvature ()
Compression failure of unconfined concrete
Compression failure of confined concrete
Buckling of longitudinal bars
Fracture of the longitudinal reinforcement
Low cycle fatigue of longitudinal reinforcement
Failure in the lap-splice zone

is the ultimate concrete compression strain for unconfined concrete and is limited to 0.005; is the distance from the extreme compression fiber to the neutral axis; is the yield curvature given by the following equation: ; is equal to the expected yield strength of the longitudinal reinforcement divided by the modulus of elasticity; is the length between the center lines of the transverse reinforcement; is distance measured from centerline of the perimeter stirrup to the extreme compression fiber of the cover concrete; is the ultimate strain of the confined concrete and is determined by ; is strain corresponding to the maximum stress of the transverse rebars; is yield stress of the transverse steel; is volumetric ratio of transverse steel; is confined concrete strength; is the distance from the extreme compression fiber to the centroid of the nearest compression rebars; is limited to a value of 0.10 or less and is the effective depth of the cross section; is plastic strain amplitude, as given by ; is given by provided that: 2 ≤ ≤ 10; is natural period of vibration of the bridge; is the length of the lap-splice that is provided; is the lap-splice length ; is plastic hinge length. and if is smaller than ; is the expected strength of concrete surrounding the lap-splice zone; is the shear length of the member; is the curvature ductility at the initial breakdown of bond in the lap-splice zone.