Choose 1/2" (12.7mm) doubler plate secured with a 3/8" (9.53mm) fillet weld min
Determine if continuity plates are required;
Determine demand;
Pbf = A f Fye = A f R y Fy = 0.420" (5.025" )1.5(36ksi) = 114 k (507.1KN)
Determine capacity;
φ n = φ (2.5k + N)Fyw t w + A st Fyst ]
R
[
where;
k = 1.0" (25.4mm)
distance from outer surface to toe of fillet for the
column
N = tbf = 0.420" (10.67mm)
thickness of the beam flange
Fyw = 50ksi (344.8MPa)
yield strength of the column web
tw = 0.285" (7.24mm)
thickness of column web
Ast =
area of the stiffner
Fyst = 36ksi (248.2MPa)
yield strength of the stiffener
φ= 1.0
Pbf - (2.5k + N)Fyw t w
114 k - (2.5(1.0" ) + 0.420" )50ksi(0.285" )
= 2.01 - in2 > 0
A st =
=
36ksi
Fyst
(Ast = 1.30X103 mm2)
Therefore, stiffeners with a total area of at least 2.01-in2 (1.30X103 mm2) total are required.
Design stiffeners in accordance with AISC LRFD 2nd ed. section K.9;
t cw b b
b
t cw
⇒ b st ≥ b
b st +
≥
-
2
3
3
2
where; bst =
width of a single stiffener
bb =
width of the beam flange
tcw =
thickness of the column web
b b t cw 5.025" 0.285"
b st =
-
=
-
= 2.37" (60.2mm), Say two stiffeners with bst = 3.0" (76.2mm)
2
2
2
2
t
t st ≥ bf
where; tst =
thickness of a single stiffener
2
tbf =
thickness of the beam flange
0.420" t b
, (Ast )total = 0.375"(3.0")2 = 2.25-in2 > 2.01-in2 O.K.
=
use; tst = 0.375" > 0.210" =
2
2
(Ast)total = 1.45X103 mm2 > 1.30X103 mm2)
(tst = 9.53mm > 5.33mm)
Check local buckling of the stiffeners;
b st
3.0"
95
95
=
= 8.0 < 15.83 =
=
O.K.
t st
0.375"
36ksi
Fy,st
where; Fy,st = yield strength of the stiffener
Design welds for the stiffeners;
Stiffener to column web;
(per AISC LRFD 2nd ed. table J2.4, based on stiffener
Minimum weld size = 3/16" (4.76mm)
thickness)
Size required for strength;
H4-52
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