Page 273 - Civil Engineering Formulas

CHAPTER 9
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 V ,
u
kip (kN 4.448 kip), of flexural members may be computed from the fol-
lowing:
V u 0.54F yw A w when h

t w (9.1)
0.54 F yw A w h
V u when 1.25 (9.2)
h/t w t w
when h
23,760kA w
V u 1.25 (9.3)
(h/t w ) 2 t w
where F specified minimum yield stress of web, ksi (MPa 6.894 ksi)
yw
2
2
A web area, in (mm ) dt
w w
187 2 k/F yw
2
k 5 if a/h exceeds 3.0 or 67,600/(h/t ) , or if stiffeners are not required
w
2
5 5/(a/h) , otherwise
Stiffeners are required when the shear exceeds V . In unstiffened girders,
u
h/t may not exceed 260. In girders with stiffeners, maximum h/t permitted is
w
w
for a/h 1.5 or 14,000/ F yf (F yf 16.5) for a/h > 1.5 , where F
2,000/ Fyf yf
is the specified minimum yield stress, ksi, of the flange. For shear capacity with
tension-field action, see the AISC specification for LRFD.
207