Civil Engineering Reference
In-Depth Information
2
T
M
f
M
b
t
p
x
T
B
T
Q
b
a
M
f
M
b
FIGURE 9.14
Prying action on a bolted tension joint.
However, as shown in Figure 9.14, the bolts in tension connections are subjected to
additional tensile forces,
T
Q
, created by the prying action resulting from the flexibility
of the connection leg. From Figure 9.14, the bending moment at the bolt line,
M
b
,is
A
nb
A
gf
M
b
=
A
nb
A
gf
α
T(b)
=
M
f
+
M
f
+
M
f
=
M
f
(
1
+ αη
)
(9.32)
w
b
t
p
4
F
y
,
and with
M
f
=
w
b
t
p
F
y
4
M
f
=
αη
T
Q
(a)
=
M
b
= αη
,
(9.33)
where
T
is the applied tensile force per bolt;
T
Q
is the prying tensile force per bolt;
T
B
=
A
nb
/A
gf
;
A
nb
is the net area of
the flange at the bolt line;
A
gf
is the gross area of the flange at the intersection with
the web plate;
T
+
T
Q
is the total tensile force per bolt;
η =
M
b
/M
f
and depends on
T
Q
/T
; and
w
b
i
is the tributary area for
prying of each bolt
i
(see
Figure 9.10b
).
α =
