## Alz

kc = 4//(h/tw), 0.35 < kc < 0.763 bf = compression flange width tf = compression flange thickness Lb = lateral unbraced length of the girder rT = P[(tfb3/12 + hctW/72)/(bftf + hctw/6)]

hc = twice the distance from the neutral axis to the inside face of the compression flange less the fillet tw = web thickness

Fyf = yield stress of compression flange (ksi) Cb = Bending coefficient (see Section 4.5)

Fcr must be calculated for both flange local buckling and lateral torsional buckling. The smaller value of Fcr is used in Equation 4.93.

The plate girder bending strength reduction factor RPG is a factor to account for the nonlinear flexural stress distribution along the depth of the girder. The hybrid girder factor is a reduction factor to account for the lower yield strength of the web when the nominal moment capacity is computed assuming a homogeneous section made entirely of the higher yield stress of the flange.

### 4.10.1.2.2 Shear Strength Criterion

Plate girders can be designed with or without the consideration of tension field action. If tension field action is considered, intermediate web stiffeners must be provided and spaced at a distance, a, such that a/h is smaller than 3 or [260/(h/tw)]2, whichever is smaller. Also, one must check the flexure-shear interaction of Equation 4.96, if appropriate. Consideration of tension field action is not allowed if

• The plate girder is a hybrid girder

• The plate girder is a web tapered girder

• a/h exceeds 3 or [260/(h/tw)]2, whichever is smaller

The design shear strength, f vVn, of a plate girder is determined as follows:

If tension field action is not considered: fvVn are the same as those for beams as given in Equations 4.49 to 4.51.

If tension field action is considered and h/tw < 1.10v/(kv£/Fyw):

where

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