Civil Engineering Reference
In-Depth Information
Example 9.4
Design the slip-resistant bolted connection for some secondary wind bracing
65 ksi), and
7/8 in. diameter A325 high-strength steel bolts are used in the connection for
this 7 ft long member.
50 ksi and
F
U
=
T
=
50 kips,
f
bv
=
17 ksi (slip-resistant connection allowable bolt shear)
Secondary and bracing member connections must be designed for the
lesser of the allowable strength of the member or 150% of the calculated
maximum forces in the member.
T
=
1.5
(
50
)
=
75 kips
Allowable tensile strength o
f
member (see Chapter 6)
Shear lag effect,
U
0.81. However, AREMA
recommends the use of 0.60 for single angle connections.
Effective net area
=
1
−
(x/L)
=
1
−
(
1.68
/
9
)
=
2.85 in.
2
=
A
ne
=
0.60
(
5.75
−
2
(
1
)(
0.5
))
=
Allowable strength
=
0.47
(
65
)(
2.85
)
=
87.0 K or
=
0.55
(
50
)(
5.75
)
=
158.1 K
Design connection for 75 kips axial tension.
Member
The number of bolts in single shear (single shear plane or faying surface):
75
75
17
(
0.60
)
=
75
10.2
=
17
d
b
/
4
=
n
=
7.4, use minimum 8 bolts.
π
check bearing stress
75
8
(
0.375
)(
1.00
)
=
σ
bc
=
25.0 ksi for a minimum 3
/
8 in. thick gusset plate,
l
e
F
u
2
d
b
≤
(
3.5
)(
65
)
2
(
7
/
8
)
f
B
≤
≤
130 ksi
6.5"
3.5"
1.5"
2.5"
L
6×6×1/2
T
18"
A
= 5.75 in.
2
x
3 @ 3" = 9"
FIGURE E9.4
