16.1–16 MEMBER PROPERTIES [Sect. B4.
Specification for Structural Steel Buildings, June 22, 2010AMERICAN INSTITUTE OF STEEL CONSTRUCTION
TABLE B4.1aWidth-to-Thickness Ratios: Compression Elements
Members Subject to Axial Compression
Examples
LimitingWidth-to-Thickness
Ratio �r
(nonslender/slender)
Width-to-Thickness
RatioDescription of
Element
Cas
e
Flanges of rolled I-shaped sections,plates projectingfrom rolled I-shapedsections; outstandinglegs of pairs ofangles connectedwith continuous contact, flanges ofchannels, andflanges of tees
Flanges of built-up I-shaped sectionsand plates or anglelegs projecting frombuilt-up I-shapedsections
Legs of singleangles, legs of double angles withseparators, and allother unstiffenedelements
Stems of tees
Webs of doubly-symmetric I-shapedsections and channels
Walls of rectangularHSS and boxes ofuniform thickness
Flange cover platesand diaphragmplates between linesof fasteners or welds
All other stiffenedelements
Round HSS
b/t
b/t
b/t
d/t
h/tw
b/t
b/t
b/t
D/t
Sti
ffen
ed E
lem
ents
Un
stif
fen
ed E
lem
ents
0 75.EFy
0 56.EFy
0 64.k EFc
y
0 45.EFy
1 49.EFy
1 40.EFy
1 40.EFy
1 49.EFy
0 11.EFy
1
2
3
4
5
6
7
8
9
[a]
Sect. B4.] MEMBER PROPERTIES 16.1–17
Specification for Structural Steel Buildings, June 22, 2010AMERICAN INSTITUTE OF STEEL CONSTRUCTION
TABLE B4.1bWidth-to-Thickness Ratios: Compression Elements
Members Subject to Flexure
Examples
LimitingWidth-to-Thickness Ratio
�p �r
(compact/ (noncompact/noncompact) slender)
Width-to-Thickness
RatioDescription of
Element
Cas
e
Flanges of rolled I-shaped sections,channels, and tees
Flanges of doublyand singly symmet-ric I-shaped built-upsections
Legs of singleangles
Flanges of all I-shaped sectionsand channels in flexure about theweak axis
Stems of tees
Webs of doubly-symmetric I-shapedsections and channels
Webs of singly-symmetric I-shapedsections
Flanges of rectangular HSSand boxes of uniform thickness
Flange cover platesand diaphragmplates betweenlines of fasteners or welds
Webs of rectangularHSS and boxes
Round HSS
b/t
b/t
b/t
b/t
d/t
h/tw
hc/tw
b/t
b/t
h/t
D/t
Sti
ffen
ed E
lem
ents
Un
stif
fen
ed E
lem
ents
3 76.EFy
0 38.EFy
0 54.EFy
0 84.EFy
hh
EF
M
M
c
p y
p
y
r
0 54 0 092
. .−⎛
⎝⎜⎞
⎠⎟
≤ λ
1 12.EFy
1 12.EFy
2 42.EFy
0 07.EFy
10
11
12
13
14
15
16
17
18
19
20
[a] [b]
0 38.EFy
0 38.EFy
1 0.EFy
0 95.k EFc
L
0 91.EFy
1 0.EFy
5 70.EFy
1 03.EFy
1 40.EFy
5 70.EFy
1 40.EFy
5 70.EFy
0 31.EFy
[c]
[a] kc = 4� but shall not be taken less than 0.35 nor greater than 0.76 for calculation purposes. [b] FL = 0.7Fy for major axis bending of compact and noncompact web built-up I-shaped members with Sxt /Sxc ≥ 0.7;
FL = FySxt /Sxc ≥ 0.5Fy for major-axis bending of compact and noncompact web built-up I-shaped members with Sxt /Sxc < 0.7.[c] My is the moment at yielding of the extreme fiber. Mp = plastic bending moment, kip-in. (N-mm)E = modulus of elasticity of steel = 29,000 ksi (200 000 MPa)Fy = specified minimum yield stress, ksi (MPa)
h tw/
Recommended
