Civil Engineering Reference
In-Depth Information
9.3.4.1.1.3 Allowable Bearing Stress in Connections
Bearing failures are
manifested as either yielding due to bearing of the connection elements against the
bolt and/or block shearing of the connection elements near an edge.
The ultimate bearing strength,
F
B
, of the connection element material bearing on
the bolt shank is related to the ultimate tensile strength,
F
U
, by the following linear
relationship (Kulak et al., 1987):
l
e
d
b
F
U
,
F
B
=
(9.23)
where
l
e
is the distance from the centerline of the bolt to the nearest edge in the
direction of the force and
d
b
is the diameter of the bolt. Using FS
2.5 against
bearing on the plate material and theAREMA (2008) recommendation that
l
e
≥
=
3
d
b
,
results in an allowable bolt bearing stress,
f
B
,of
F
B
FS
=
f
B
=
1.2
F
U
.
(9.24)
The yield strength in pure shear,
F
v
(see Chapter 2), is
F
y
√
3
F
v
=
(9.25)
2
t
p
l
e
−
F
y
√
3
=
1.15
t
p
l
e
−
F
y
,
d
b
2
d
b
2
P
y
=
(9.26)
where
t
p
is the plate thickness.
The bearing strength of the bolt,
F
bB
,is
F
bB
=
f
B
d
b
t
p
,
(9.27)
which must not exceed the yield strength of the shear block given by Equation 9.26.
Therefore,
1.15
t
p
l
e
−
F
y
≥
d
b
2
P
y
=
F
bB
=
f
B
d
b
t
p
.
(9.28a)
P
y
d
b
l
e
FIGURE 9.12
Shear block failure due to bolt bearing.
