Civil Engineering Reference
In-Depth Information
25
crp
20
[4]
[15]
a
d
15
a
2
12(1- )
E
--------------------------
k
---------------
()
10
crp
=
=1
2
d/t
2
=1
5
0.6
a/d=
∞
0
0
0
0.5
1.0
1.5
2.0
2.5
3.0
Panel aspect ratio
a/d
Figure 4.26
Buckling coefficients of plates in bearing.
can be expressed as
π
2
E
12
(
1
−
ν
2
)
k
σ
(
d
/
t
)
2
σ
crp
=
(4.45)
inwhichthebucklingcoefficient
k
σ
varieswiththepanelaspectratio
a
/
d
asshown
in Figure 4.26.
When a patch-bearing load acts along a reduced length
α
a
of the top edge of
the panel, the value of
α
k
σ
is decreased. This effect has been investigated [15],
andsomevaluesof
α
k
σ
areshowninFigure4.26.Thesevaluessuggestalimiting
value of
α
k
σ
=
0.8 approximately for the case of unstiffened webs
(
a
/
d
→∞
)
with concentrated loads
(α
→
0
)
.
For the case of a panel in combined bearing, shear, and bending, it has been
suggested [6, 15] that the elastic buckling stresses can be determined from the
interaction equation
τ
cr
τ
cro
2
σ
crl
σ
crlo
2
σ
crp
σ
crpo
+
+
=
1
(4.46)
inwhichthefinalsubscripts
o
indicatetheappropriateelasticbucklingstresswhen
only that type of loading is applied. Some specific interaction diagrams are given
in [15].
4.6.2 Ultimate strength
The ultimate strength of a thick web in bearing depends chiefly on its yield stress
f
y
. Although yielding first occurs under the centre of the bearing plate, general
Search WWH ::
Custom Search