Fbr

Shear transfer criterion: If tension field action is considered, the total shear transfer, in kip/in., of the stiffeners shall not be less than f-s=Vicf <«»

where Fyw is the web yield stress (ksi) and h is the clear distance between flanges (in.).

The value of fvs can be reduced proportionally if the computed average web shear stress, fv, is less than Fv given in Equation 4.88.

4.10.1.2 Load and Resistance Factor Design 4.10.1.2.1 Flexural Strength Criterion

Doubly or singly symmetric, single web plate girders loaded in the plane of the web should satisfy the flexural strength criterion of Equation 4.38. The plate girder design flexural strength is given by

For the limit state of tension flange yielding:

For the limit state of compression flange buckling:

where

Sxt = section modulus referred to the tension flange = Ix/ct Sxc = section modulus referred to the compression flange = Ix/cc Ix = moment of inertia about the major axis ct = distance from neutral axis to extreme fiber of the tension flange cc = distance from neutral axis to extreme fiber of the compression flange RPG = plate girder bending strength reduction factor

= 1 - ar[hc/tw - 5.70pE/Fcr)]/ [1200 + 300ar] < 1.0 R = hybrid girder factor

= [12 + ar(3m- m3)]/[12 + 2ar] < 1.0 (R = 1 for nonhybrid girder) ar = ratio of web area to compression flange area m = ratio of web yield stress to flange yield stress or ratio of web yield stress to Fcr Fy. = tension flange yield stress

Fcr = critical compression flange stress calculated as follows:

Limit state

Range of slenderness

Flange local buckling

Lateral torsional buckling bf E

Lb E

rT VFyf

v Fyf rT

Lb IY

rT VFyf

Fyf /kc

0 0