CIVIL ENGINEERING FORMULAS

CHAPTER 9

207

BUILDING AND

STRUCTURES

FORMULAS

LOAD-AND-RESISTANCE FACTOR
DESIGN FOR SHEAR IN BUILDINGS

Based on the American Institute of Steel Construction(AISC)specifications for
load-and-resistance factor design(LRFD) for buildings, the shear capacity Vu,
kip (kN4.448kip), of flexural members may be computed from the fol-
lowing:

(9.1)

(9.2)

(9.3)

whereFywspecified minimum yield stress of web, ksi(MPa6.894ksi)
Awweb area, in^2 (mm^2 )dtw


k5 if a/hexceeds 3.0 or 67,600/(h/tw)^2 , or if stiffeners are not required

 5 5/(a/h)^2 , otherwise

Stiffeners are required when the shear exceeds Vu. In unstiffened girders,
h/twmay not exceed 260. In girders with stiffeners, maximum h/twpermitted is
for or for ,whereFyf

is the specified minimum yield stress, ksi, of the flange. For shear capacity with
tension-field action, see the AISC specification for LRFD.

2,000/Fyf a/h1.5 14,000/Fyf (Fyf16.5) a/h > 1.5

1872 k/Fyw

Vu

23,760kAw

(h/tw)^2

when

h

tw

1.25

Vu

0.54FywAw

h/tw

when 

h

tw

1.25

Vu0.54FywAw when

h

tw