Page 245 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

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CRITERIA FOR BUILDING DESIGN

CRITERIA FOR BUILDING DESIGN 5.25

5.6.1 Members with Unstiffened or Stiffened Webs—
Tension Field Action Neglected

This article applies to webs of singly or doubly symmetric members and channels subject to shear
in the plane of the web. The nominal shear strength V n of unstiffened or stiffened webs for the limit
states of shear yielding and shear buckling is given by
(5.88)
V n = 0.6F y A w C v
2
2
where A w = overall depth times web thickness dt w , in (mm ), and the coefficient C v is as defined
below.
/
For webs of rolled W shapes with ht/ w ≤ . 224 E F , only the limit state of shear yielding
y
applies: φ v = 1.00 (LRFD), Ω v = 1.50 (ASD), and C v = 1.0. All current W, S, and HP shapes listed in
ASTM A6, except W44 × 230, W40 × 149, W36 × 135, W33 × 118, W30 × 90, W24 × 55, W16 ×
26, and W12 × 14, meet this criterion for steels with F y ≤ 50 ksi (345 MPa).
For webs of all other doubly symmetric shapes (excluding HSS) and singly symmetric sections
and channels, φ v = 0.90 (LRFD), Ω v = 1.67 (ASD), and C v is as follows.
/
When ht/ ≤ . 110 k E F , the limit state of shear yielding applies:
w v y
C v = 1.0 (5.89)
All current W, S, M, and HP shapes listed in ASTM A6, except W44 × 230, M12 × 11.8, M12 × 10.8,
M12 × 10, M10 × 8, and M10 × 7.5 meet this criteria for steels with F y ≤ 50 ksi (345 MPa).
When 110. kE /F < / h t ≤ 137 kE /F , the limit state of shear buckling applies:
.
v
y
v
w
y
110 kE F y
/
.
v
C = (5.90)
v
/
ht w
/
When ht/ w > . 137 k E F , the limit state of shear buckling applies:
v
y
151 Ek v
.
C = (5.91)
v
ht )
(/ w 2 F y
For unstiffened webs with h/t w < 260,
k v = 1.2 for the stem of tee shapes
k v = 5.0 for all other cases
For stiffened webs,
a a  260  2
k = 5 when > 3 0 . or >   (5.92)
v
ht )
h h  (/ w 
k =+ 5 for all other cases (5.93)
5
v
(/ 2
ah)
where a = distance between transverse stiffeners, in (mm)
h = for rolled shapes, the clear distance between flanges less the fillet or corner radii, in (mm)
h = for built-up welded sections, the clear distance between flanges, in (mm)
h = for built-up bolted sections, the distance between fastener lines, in (mm)
h = for tees, the overall depth, in (mm)
Transverse stiffeners are not required where h/t w ≤ 246. / EF y , or where the required shear
strength is less than or equal to the available shear strength, determined from the preceding equa-
tions with k v = 5. However, where transverse stiffeners are used to develop the web shear strength,
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