Civil Engineering Reference
In-Depth Information
Own weight of stringer
¼
1
:
5kN
=
m
Total dead load
¼ g
vk
¼
4
:
=
m
Assuming the stringers are simply supported by the cross girders, we can
calculate the maximum shear force and bending moment due to dead loads
on a stringer (see
Figure 4.128
)
as follows:
8kN
Q
D
:
L
:
¼ g
vk
L
=
2
¼
4
:
8
4
:
5
=
2
¼
10
:
8kN
M
D
:
L
:
¼ g
vk
L
2
5
2
=
8
¼
4
:
8
4
:
=
8
¼
12
:
15 kNm
Live Loads
Considering the axle live loads on the bridge components according to Load
Model 71, which represents the static effect of vertical loading due to normal
rail traffic as specified in EC1 [3.1] (see
Figure 4.129
), three cases of loading
for the evaluation of maximum bending moment due to the live loads on a
stringer can be studied. The first case of loading is that the centerline at mid-
span of a stringer divides the spacing between the resultant of the concen-
trated live loads and the closest load, with maximum bending moment
g
vk
= 4.8 kN/m
4.5 m
10.8 kN
+
S.F.D.
-
10.8 kN
B.M.D.
+
12.15 kN m
Figure 4.128 Straining actions from dead loads acting on a stringer.
250 250 250 250 kN
q
vk
= 80 kN/m
q
vk
= 80 kN/m
1600
1600
800
800
Figure 4.129 Axle live loads on the bridge conforming to Load Model 71 specified in
EC1 [3.1].
800
800
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