Civil Engineering Reference
In-Depth Information
traffic on mainline railways, “Load Model SW/2” to represent heavy loads,
“high-speed load model (HSLM)” to represent the loading from passenger
trains at speeds exceeding 200 km/h, and finally Load Model “unloaded
train” to represent the effect of an unloaded train. Load Model 71 represents
the static effect of vertical loading due to normal railway traffic. The load
arrangement and the characteristic values for vertical loads shall be taken into
account as shown in
Figure 3.1
.
The characteristic values given in
Figure 3.1
shall be multiplied by factor
a
on lines carrying railway traffic that is heavier
or lighter than normal railway traffic. When multiplied by the factor
a
, the
loads are called “classified vertical loads.” This factor
a
varies from 0.75 to
1.46. Also, the actions comprising equivalent vertical loading for earthworks
and earth pressure effects, centrifugal forces, nosing force, traction and brak-
ing forces, combined response of structure and track to variable actions,
derailment actions for accidental design situations, and Load Model SW/
0 for continuous span bridges shall be multiplied by the same factor
a
.
For checking the limits of deflection, classified vertical loads and other
actions enhanced by
a
shall be used (except for passenger comfort where
a
shall be taken as unity). Load Model SW/0 represents the static effect
of vertical loading due to normal railway traffic on continuous beams. Load
Model SW/2 represents the static effect of vertical loading due to heavy rail-
way traffic. The load arrangements SW/0 and SW/2 shall be taken as shown
in
Figure 3.2
, with the characteristic values of the vertical loads according to
Table 3.1
. For some specific verifications, a particular load model is used,
called “unloaded train.” The Load Model “unloaded train” consists of a ver-
tical uniformly distributed load, with a characteristic value of 10.0 kN/m.
Q
vk
= 250 kN 250 kN 250 kN 250 kN
q
vk
= 80 kN/m
q
vk
= 80 kN/m
0.8 m
1.6 m
1.6 m
1.6 m
0.8 m
Figure 3.1 Load Model 71 and characteristic values for vertical loads of standard trains
q
vk
q
v
a
Figure 3.2 Load Models SW/0 and SW/2 of standard trains specified in EC1 [
3.1
].
c
a
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