PROJECT: STEEL BUILDING DESIGN CASE STUDY
SUBJECT: Bracing connection, gusset plate design.
Brace line B1, second floor.
SHEET 122 of 131
f = resistance factor
Fy = specified (ASTM) minimum yield stress
Fu = specified (ASTM) minimum tensile strength
Rn = strength
t = thickness of connected part
Pu = factored load to be resisted
d = diameter of the bolt
eb = one-half the depth of the beam, in.
ec = one-half the depth of the column, in.
db = depth of the beam, in.
dc = depth of the column, in.
w.p. = working point.
N = horizontal distance of gusset plate, in.
V = vertical distance of gusset plate, in.
a = distance from the face of the column flange to the centroid of the gusset-to-beam connection, in.
b = distance from the face of the beam flange to the centroid of the gusset-to-column connection, in.
Aw =cross section area of the whitmore section
Pu =
B
Elevation View
C
127.0 k
D
96 k
13
A
E
30
Plan View
Member A-E, Interior floor girder:
W24x68
ASTM 992
db = #N/A in
Fy =
50
ksi
Fu =
65
ksi
Column
W10x49
Member A-B, Interior column:
W10x49
ASTM 992
dc = #N/A in
Fy =
50
ksi
Fu =
65
ksi
Member A-C, Brace:
2L6x4x1/2LLBB A36
Fy =
36
ksi
Fu =
58
ksi
Gusset Plate
W.P.
Brace
2L6x4x1/2
13
15
Girder
W24x68
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PROJECT: STEEL BUILDING DESIGN CASE STUDY
SUBJECT: Bracing connection, gusset plate design.
SHEET 123 of 131
Use A325-N bolts in standard holes,3/4 in diameter.
fRn =
Design shear strength of one bolt, double shear (LRFD Table 7-10)
31.8 k
Check bearing strength @ each bolt hole:
fRn = f (2.4 * d * t * Fu) =
(f = 0.75)
45.7
kips >
31.8
kips
OK!
Check tension yielding on the Whitmore section:
Column
Brace
13
Gusset Plate
15
Whitmore section
Girder
y = tan 30o * 6 =
3.5
in
y
30°
6
*Note: Assume simplified Whitmore section (double
dashed area) for the purpose of this lab. This design will
be more conservative.
fRn = f (Fu * Aw) =
248.0 kips >
127.0
kips
(f = 0.9)
Aw = (y + y + 2.5(Perp. distance between center of holes))*0.5
OK!
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PROJECT: STEEL BUILDING DESIGN CASE STUDY
SUBJECT: Bracing connection, gusset plate design.
SHEET 124 of 131
Distribution of brace force to beam and column:
(Uniform force method)
From the member and frame geometry
eb = db/2 =
ec = dc/2 =
tanq =
#N/A
#N/A
1.154
q
in
in
13
15
in order to remain free of moments on the connection interfaces, the following expression must be satisfied:
tan q * eb - ec = a - b * tan q
a - b * tan q =
#N/A
allow 1/2 in. between gusset and column
for the setback
in
N
Brace
Column
0.5
13
15
Gusset Plate
V
b
ec
a
Girder
eb
W.P.
Try a gusset plate :
1/2
a=
b=
in.
x
16.5
6.7
16 1/8
in. horizontally x
Use
a=
in. vertically
in
in
a' = tan q * eb - ec + b * tan q =
a - a' =
5 5/4
#N/A
in
16.5
in and
#N/A in
#N/A
b=
6.7
in
N=
V=
16 1/8 in
5 5/4 in
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