Civil Engineering Reference
In-Depth Information
25 cm
1.6
x
x
1.6
25 cm
22
22
1.6
Figure 4.121 Intermediate stability web stiffeners.
p
a
1
1500
1740
¼
0
h
w
¼
:
86
<
¼
1
:
414 ThenO
ð
:
K
:
Þ
5
h
2
w
t
w
5
174
3
6
3
1
:
1
:
1
:
5cm
4
and
I
st
a
1
¼
¼
1438
:
150
2
¼
18333
6
3
6
25
3
3
2
4cm
4
I
st
¼
45
:
6
1
:
=
12 + 2
1
:
=
12 + 40
13
:
:
5cm
4
Then,O
>
1438
:
ð
:
K
:
Þ
4.4.5 Design of Field Splices
Figure 4.106
shows the locations of filed splices for the investigated bridge.
Designing the splice requires determination of size of connecting plates as
well as the number of bolts of the filed splice shown in
Figure 4.122
.
The area of the upper flange plate equals to 50
3
¼
150 cm
2
; this can be
compensated by three flange splice plates having cross-sectional area of
50
1.6 and 2
23
1.6 cm
2
with a total area of 153.6 cm
2
, which is
greater than the original area. Also, the area of the lower flange plate equals
to 70
3
¼
210 cm
2
; this can be compensated by three flange splice plates
having cross-sectional area of 70
1.6 and 2
33
1.6 cm
2
with a total area
of 217.6 cm
2
, which is greater than the original area, while the area of web
plate
¼
174
1.6
¼
278.4 cm
2
can be compensated by two web splice plates
having cross-sectional area of 2
170
1.0 cm
2
with a total area of 340 cm
2
,
which is governed by the minimum thickness (10 mm) of plates used in steel
bridges. The top row of bolts in the web (see
Figure 4.122
) is subjected to
horizontal shear from the bending moment distribution, assuming the yield
stress reached at the extreme and lower fibers of the flanges, and vertical
shear from the applied loads. Using a spacing of 8.5 cm between two adja-
cent bolts, an edge spacing of 4.25 cm and a hole of 3 cm (2.7 cm bolt
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