Civil Engineering Reference
In-Depth Information
Exp
Fix
Transverse floorbeams (steel deck plate)
Skew angle
Exp
Fix
Stringers & floorbeams (open deck ties)
Expansion bearings
Expansion devices
FIGURE 3.10
Square track support at skewed ends of steel railway spans over piers.
3.2.4.2
Vertical Geometry of the Bridge
In addition to a ground profile survey at the crossing, the dimensions generally
required to develop a preliminary general arrangement of a railway bridge crossing
are shown in
Figure 3.11.
These basic dimensions provide the information for prelim-
inary design of the superstructure elements, where
L
is the length of the bridge and
is given by
L
=
ns
i
=
1
L
i
, where
i
is the span number, ns is the number of spans and
L
i
is the length of spans;
W
i
is the width of spans;
H
i
is the height (depth) of spans;
H
c
i
is the construction depth of spans and is equal to
H
i
for deck type spans;
H
w
is
the distance from the base-of-rail to water level;
g
is the grade of the bridge.
The length of spans is generally governed by site conditions, such as hydraulic or
geotechnical considerations, or transportation corridor clearances (railroad, highway,
or marine). Width is controlled by the number of tracks and the applicable railway
company and regulatory clearances.
3.3 PRELIMINARY DESIGN OF STEEL RAILWAY BRIDGES
3.3.1 B
RIDGE
A
ESTHETICS
Bridge aesthetics may be considered in terms of the structure itself and/or its inte-
gration into the environment. Bridge aesthetics is of particular importance in urban
or accessible natural environments. Perception of beauty varies extensively among
