Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02349315 2001-05-11
Y:1SL00110785 CA\as filed spec 010511 A4 versi0n.wpd
STRUCTURAL SUPPORT FOR ELE4~ATED RAILWAY
Field of the Invention
This invention relates to structural support for railways, particularly direct-
fixation-rail
elevated railways, and more particularly to an econorr~ically attractive
structural support
system in which lengthy precast girders are set in place and allowed to
settle, and then
smaller precast guideway deck slabs are set in place atop the girders,
connected thereto,
and aligned. The guideway deck slabs are advantageously designed to include
upper
surface features that facilitate connection, canting and alignment.
Background of the Invention
Elevated railways require structural support that accommodates curvature of
the
railway both horizontally and vertically. Manufacture of the structure,
alignment of the rail
supports and related portions of the guideway and proviision of the desired
cant to the rail
supports are expensive and time-consuming under prior practice. One reason for
the
problem is that, for reasons of economy, any girder/guicieway structure should
be formed
in discrete lengths that are as long as possible. In conventional practice,
this gives rise
to a number of disadvantages associated with propeir surfacing and alignment,
partly
because the guideway and underlying support girder are manufactured as a
single integral
unit that limits the practicable length, requires hand finishing of the
uppermost surface(s),
and does not permit the use of either optimum or inexpensive connection
elements and
other rail hardware. Furthermore, variations in camber and alignment caused by
concrete
shrinkage, creep, etc. that occur in the girder portion of the structure
directly affect the
geometry of the guideway itself, and frequently necessitate the placing of
shims, etc. along
the length of the guideway to compensate for such dimensional variations as
the girder
concrete sets.
Conventional structural supports for elevated railways of the linear induction
motor
(LIM) type are made up of units each of which compri:>es a concrete deck
slablparapet
structure (the "guideway") for the rail support and for mounting the power
rail and LIM
reaction rail, and an underlying U-shaped girder that is farmed integrally
with the guideway
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CA 02349315 2001-05-11
portion so as to form a closed box-like guideway/girder structure. The girders
span
longitudinally between vertical support columns in elevated segments of the
railway. The
girders with integral deck slabs are typically cast in sifu, and thus creep,
shrinkage, etc.
in the girder negatively affect the geometry and alignment of the guideway
deck for
supporting the carriage rails and the LIM reaction rail. While manufacturing
economies
of scale would be obtained by making the girders as long as possible, it is
easier to correct
misalignment problems in shorter deck segments llhan in longer ones, so design
compromises are necessary.
More specifically, the conventional girderlguideway structure is cast as an
integral
unit using an interior collapsible form to define the interior walls of the
girder and the
undersurfiace of the guideway deck slab, as well as external forms for the
undersurface
of the girder and the more or less upright surfiaces leaving, however, the
entire top surface
of the concrete in the guideway deck slab to be hand-finished, which is labour-
intensive.
The upper horizontal surfaces of the parapets (the outeir walls) of the
guideway also have
to be hand-finished. Further, because of the hand-fini;>hing, it is necessary
that the use
of stud bolts, etc. protruding from the deck slab surface be avoided. This
implies that the
attachment elements for the rail support and for the LIM reaction rail
embedded in the
deck slab have to be inset female elements as illustrated in Figure 1, that
threadedly mate
with matching male bolts that are inserted once the (hand finishing is
complete. The
combination of male and female elements are expensive relative to the cost of
stud bolts
that could, were it not for the need to provide a smooth, flat finish, be
embedded in the
concrete before it has set.
Moreover, the rail support elements for a conventionally supported rail have
to be
trapezoidal in transverse section so as to provide an upper inclined surface
to which the
carriage support rail may be directly attached, thereby to cant the rail.
Because of the
occurrence of creep, shrinkage, etc. in the girder (which conventionally
includes the
guideway deck slab as a top flange), the dimensions of an ideal rail support
element for
canting the rail cannot be predicted with confidence - shims, etc. are
typically used to
make the appropriate adjustments. A further problem is that the LIM reaction
rail has to
be positioned appreciably above the deck slab surfiace~ because of the
geometry of the
LIM reaction rail relative to the LIM motor on the underside of the railway
carriage. This
implies that the stud bolts supporting the LIM reaction rail have to extend
appreciably
above the upper surface of the guideway deck slab. As significant stresses are
applied
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CA 02349315 2001-05-11
to the bolts as trains pass over the reaction rail, either the bolts have to
be oversized or
the risk of failure due to metal fatigue is higher than would be desired,
simply because of
the extent of unsupported protrusion of the bolts abovE; the deck slab
surface.
Summary of the Invention
According to a principal aspect of the invention, the girder and the guideway
slablparapet units are separately precast. For that reason, the guideway deck
slablparapet units (frequently referred to in this specification simply as
"deck slabs") may
be made relatively short (say, about 3 metres) while the underlying girder,
which has a
generally open U-shaped cross-section, may be somewhat longer than
conventional
girders (about 36 metres or possibly longer, instead of t!'~e conventional 30
metres). Note
that for any given length, the overall weight of the opE;n girder is
appreciably less than
would be the case for the conventional integrated box-structure. Since the
alignment of
guideway segments is relatively easy if the individual deck slabs are
relatively short, and
the alignment once made will persist because of the absence of creep and
shrinkage of
the precast girder, the girder can be made as long as is convenient or
economical. This
implies that anywhere from about 10 to 30 deck slabs could be mounted on a
single open
"U" shaped girder.
The foregoing structural design according to tree invention entails a number
of
significant advantages. First, all creep, shrinkage, etc. in the girder that
would result in
changes in camber and dimension throughout its length, etc. are confined to
the open "U"
shaped girder itself and have no effect on the separately formed guideway deck
slab
elements that will be mounted atop the girder. Since the guideway deck slab
elements
per se are relatively short, they can each be individually set in place and
individually
aligned along the trackway. It is not necessary to acljust cant for the rails,
etc. on a
continual basis over an elongate guideway structure;; it is easier to make
individual
adjustments to a series of deck slabs that can be assembled together
sequentially over
the longitudinal span of a girder. Furthermore, it is advantageous to permit
the concrete
of the girder to set in place and to postpone the installation of the
individual guideway
deck slabs until the girder has substantially cured, so that the guideway
configuration is
adapted to the girder as it actually exists in place rather than having to
design the
individual guideway elements to an expected final design of the girder
structure that may
or may not be realized in actuality, the latter design approach being required
for
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CA 02349315 2001-05-11
conventional structures of the sort illustrated in Figure 1.
For use with an LIM-type elevated railway, the upper surface of the generally
horizontal portion of the guideway deck slab/parapet element according to the
invention
is typically not flat but is formed in a predetermined fashion to provide or
contribute
usefully to three types of support, namely:
1. a canted concrete surface on which the rail support element may be
mounted;
2, an elevated central mount for supporting the LIM reaction rail; and
3. a shoulder intervening between the LIM reaction rail support surface and
the
rail support surface, for providing containment of the rail carriages in the
event of derailment.
Note that by providing an initial cant on the upper surface of the concrete
for
supporting the rail, each rail support element can be of generally rectangular
parallelepiped shape, which is less expensive to manufacture than the
individually canted
rail support elements of trapezoidal cross-section that heretofore have
conventionally been
used. The wheels of a conventional rail carriage have flanges on the inside
and are
slightly canted. The canting of the rails is necessary or at least highly
desirable to prevent
the carriage wheels from "hunting", i.e. continually moving from side to side
as the
carriage moves along the track, and to maintain normality of the carriage
wheel/rail
reaction forces. Note also that the precast character of the deck slab and the
provision
of an elevated central mount for the LIM reaction rail imply that conventional
and relatively
inexpensive stud bolts can be embedded in the concrete of the deck slab when
it is
formed, and used later to connect rail support elements and undersupport for
the LIM
reaction rail. Note further that because the concrete for the LIM reaction
rail mount is
elevated relative to the carriage rail support surface, the stud bolts
supporting the LIM
reaction rail can extend upwardly from the concrete surface a much shorter
distance than
that required to support the LIM reaction rail in a conventional structure.
This advantage
enables the use of smaller stud bolts or reduces the risk of support failure
or both.
Note that the upper surface of the guideway deck slab according to the
invention
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CA 02349315 2001-05-11
is formed, not hand-finished, leading to considerable cost savings in the
manufacture of
such guideway slabs. The guideway deck slabs (and the attached parapet
portions
thereof) may be formed using suitable forms for forming almost all of the
surfaces; hand-
finishing is required only for a very small pouring portal at a suitable
location, e.g. along
one lower side edge of one parapet, the forms being tilted to place this
pouring portal at
the very top of the cavity within the forms.
When the elevated railway is not of the LIN1 type, some but not all of the
advantages of the present invention can be realized. The girder and the deck
slabs can
be separately precast, with the advantages entailed by so doing; particularly,
almost all
hand finishing is avoided, and alignment is both facilitated and also stable
by reason of
the preforming. Canting for the rail support elements can be formed into the
concrete
surface underneath the support elements, permitting thE: support elements to
be relatively
inexpensively manufactured of steel plates of rectangular cross-section.
However, some
of the advantages directly associated with the elevated mount for the LIM
reaction rail will,
of course, not apply if the railway is of the overhead catenary type or some
other type not
requiring a centrally mounted LIM reaction rail.
Further, if the railway need not be elevated, k>ut requires structural support
at
ground level or in a tunnel, the deck slab design according to the invention
may be used.
In the case of installation at-grade, the deck slabs would be supported by a
continuous
foundation slab. In the case of a guideway located in a tunnel, the deck slabs
would be
supported by the tunnel bottom slab. In such a tunnel installation, the
inclusion of parapet
walls integral with the deck slabs may not be necessary, as the tunnel walls
may provide
sufficient protection against derailment. In such cases, the advantages of the
invention
obtained by the use of precast deck slabs of a type suitable for implementing
the invention
are obtainable.
SUMMARY OF THE DRAWINGS
Figure 1 (prior art) is a fragment section view of a girder fragment and
slightly more
than half of the upper track-supporting top flange of the integrated structure
with attached
parapet, for an elevated railway, manifesting conventional elevated railway
guideway
design known prior to the present invention.
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CA 02349315 2001-05-11
Figure 2 is a schematic elevation view of a portion of an elevated railway
support
structure constructed in accordance with the principles of the present
invention, illustrating
the columns, girders, and deck slab components of the elevated railway support
structure
in generalized schematic form.
Figure 3 is a cross-section through a specimen girder suitable for
implementing the
present invention, for use in an elevated railway support structure of the
type illustrated
in Figure 2.
Figure 4 is a section view of a girder and deck slab component constructed in
accordance with the principles of the present invention, for use with an
elevated railway
of the linear induction motor (LIM) type.
Figure 5 is a schematic fragment plan view of a sequence of deck slabs for a
guideway according to the present invention.
Figure 6 is a fragment elevation section detail view of the joint between two
adjacent deck slabs of the type illustrated in Figure 5.
Figure 7 is a schematic section view of a shear connection for anchoring deck
slab
members to the uppermost flange of the U-shaped girder of Figure 3.
Figure 8 is a schematic detail plan view of a grouted pocket for the shear
connection of Figure 7.
Figure 9 is a schematic section view of a pair of deck slab forms for forming
a pair
of deck slab segments of the sort illustrated in Figure 4..
Figure 10 is an exploded view of the forms of Figure 9 and a support structure
for
supporting the forms.
Figure 11 is a schematic section view of an alternative elevated railway deck
slab
constructed in accordance with some of the principles of the present
invention, for a level
unbanked portion of the guideway, with accompanying supporting girder, wherein
the
elevated railway is of a type requiring no central reaction rail.
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CA 02349315 2001-05-11
DETAILED DESCRIPTION WITH REFERENCE TO DRAWINGS
A portion of a conventional guideway (generally indicated by reference numeral
22)
for an elevated railway is shown in fragment section viE;w in Figure 1. Such
conventional
guideway typically comprises a generally box-configured girder 26 with an
integral top
flange 28 that serves as the trackway support structure, differing from the U-
sectioned
girder and separately formed deck slab of Figure 4, for Example, discussed
below. Figure
1 illustrates a fragment section of the top portion of one near-vertical wall
or web 24 of the
box-type guideway girder 26 whose generally horizontally disposed track
support flange
28, somewhat more than half of which is illustrated in Figure 1, serves
essentially the
same purpose as the deck slab 18 of Figure 4, to be discussed below. The
parapet 43,
unlike the integrally formed parapet 42 of Figure 4 to be discussed below, is
formed
separately and attached by suitable means (not shown in Figure 1 ) to the top
flange 28,
but otherwise serves essentially the same purposes as the parapet 42 of Figure
4. Figure
1 does not illustrate the remaining web structure of girder 26 nor the bottom
flange of the
girder 26, which however in such bottom and other side portions resembles the
bottom
and other side portions of girder 12 of Figure 4 to be further described. The
girder 26 in
complete section is thus generally box-shaped. Also not illustrated in Figure
1 is an initial
derailment constraint of some sort that would conventionally be provided to
limit the
transverse movement of the railway carriage if it became derailed; parapets 43
serve as
ultimate derailment constraints and also provide sound abatement. The girder
26 is
typically formed in situ, and the top surface 90 of the top flange 28 of
girder 26 is hand-
finished.
The girder 26 extends (spans) longitudinally 'from support column to support
column; the columns 16 and cross-head supports 14 illustrated in Figure 2 are
suitable
for such purpose, although intended to illustrate the more typical dimensional
relationships
of deck slabs 18 and girders 12 of the present invention, to be further
described below.
However, because the top flange 28 is formed integrally with the rest of the
structure of
the girder 26, each girder 26 is appreciably heavier than each girder 12.
Referring to Figure 2, a portion of an elevated railway generally indicated as
10,
comprises a series of girders 12 supported on cross-heads 14 mounted atop
longitudinally
spaced columns 16. Atop the girders 12 are mounted a series of substantially
contiguous
deck slabs 18 that support the rails on which a train of rail carriages 20
rides.
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CA 02349315 2001-05-11
The deck slabs 18 and the girders 12 are, according to one aspect of the
present
invention, preferably preformed of reinforced concrete. This design enables
the deck
slabs 18 to be relatively short in length compared to the length of the
girders 12. In
practice, girders 12 of up to 30 metres or more in length with deck slabs of
approximately
3 metres in length have been found to be suitable for nnost elevated railway
applications.
Of course the girders 12 may be replaced by other deck slab support means in
the case
of track guideway intended for surface use or for use in tunnels or the like.
In such cases
it may be desirable, depending upon the application, to omit the girders 12
entirely and
to provide relatively short support slabs to substitute for the near-vertical
webs 32 (Figure
3) of girders 12, or it may be sufficient to have an underlying concrete base
integrally
formed and extending underneath the trackway. The combination of long girders
with
relatively short deck slabs, all made of preformed reinforced concrete, is
economical to
manufacture and relatively easy to align.
Each girder 12 may be generally U-shaped in section as illustrated in Figure
3. The
near-vertical webs 32 of girder 12 terminate in expanded end flanges 34 whose
upper
faces 36 may be provided with connecting elements (not shown in Figure 3; see
Figure
7 and related description below) for attachment to the deck slabs 18 that will
rest on the
upper faces 36 of the girders 12. For curved sections of the track, the webs
32 may be
made of unequal height.
Figure 4 shows a representative deck slab 18 comprising a generally
horizontally
extending base 40 and side parapet walls 42. Each deck slab 18 is a single
separately
formed concrete structural unit. The specific connection elements for
attaching the deck
slab 18 to the girder 12 are not illustrated in Figure 4, but once these
connections are
made or are in the course of being made, the interface: between the
undersurface 44 of
the deck slab 18 and the upper flange faces 36 of welbs 32 of girder 12 are
grouted to
provide grouted joints 46. The grouted joints 46 connect the girder 12 and the
deck slab
18 into an integrated structural unit.
Between the parapets 42, the upper surface of each deck slab 18 comprises a
central elevated mount 62 with a top planar surface 63 .and side inclined flat
surfaces 53.
The surfaces 53 are preferably slightly inwardly canted (typically with a 1:20
cant) to avoid
"hunting" of the railway carriage wheels on the rails, and to maintain
normality of the
wheellrail reaction forces. Such canting is in accordance with conventional
design, which,
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CA 02349315 2001-05-11
however has heretofore conventionally been implemented by providing specially
formed
rail support elements, as will be further discussed below relative to Figure
1. Rails 52 of
the present invention lie on and are connected to rail support elements 55,
and if required,
aligned vertically and secured in place by shim plates 96 (Figures 4 and 5)
and stud bolts
51 embedded into the concrete of the deck slab 18.
It will be noted that rail support elements 55 connected to the side surface
portions
53 of deck slab 18 are depressed relative to a centrally elevated portion 62
above which
linear induction motor (LIM) reaction rail support plates 74 are mounted by
means of nuts
70 threaded onto stud bolts 72 suitably embedded and anchored in the elevated
portion
62 of deck slab 18. The LIM reaction rail 66 is mounted by means (not
specifically
illustrated in Figure 4) that firmly fix the reaction rail 66 onto support
plates 74 that are
fixed above the central elevated portion 62 of the deck slab 18, separated by
air space
64. Electric power for the railway carriages is supplied to power rails 38
mounted on
mounting bracket assembly 57, fixed by bolts 76 engaging female threaded
receptacles
60 embedded within the concrete of the left parapet w<~II 42 as illustrated in
Figure 4.
Note that the side surfaces 53 extend inwardly of the rails 52 for a distance
before
terminating at shoulder 68 of the elevated central LIM reaction rail support
mount portion
62 of the deck slab 18. The shoulder 68 on either sidle of the mount 62
functions as a
derailment constraint, preventing or impeding the wheels of the railway
carriage that have
become inwardly derailed from moving laterally any further than the shoulder
68.
Parapets 42 provide further derailment constraint if that provided by
shoulders 68 is
inadequate.
For a number of reasons, conventional girders 26 are appreciably shorter than
girders 12. There are three principal reasons for the disparity in maximum
length between
girders 12 and girders 26. First, as mentioned, since thE; top flange 28 is
formed integrally
with the rest of the structure of the girder 26, each girdE:r 26 will weigh
appreciably more
than each girder 12, even though the absence of parapets 43 from the initial
casting
affords some offsetting reduction in weight. As hoisting and transportation
equipment are
limited to a maximum load weight, a girder 12 (Figures 2, 4) of the same
weight as a given
girder 26 (Figure 1 ) can be appreciably longer. Consequently, for the girder
and deck slab
arrangement of the present invention, columns and cross-heads can be spaced
further
apart and fewer of them will be needed for a given job.
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CA 02349315 2001-05-11
A second reason for keeping the conventional girders 26 short is that
longitudinal
alignment problems, especially with respect to rails, teind to become more
severe as the
length of a track guideway increases. As mentioned, the deck slabs 18 of
Figure 4, being
discretely formed, can be relatively short (say, 3 m in length) while the
girders 12 can
support many deck slabs 18 in end-to-end sequence, and may be as much as 30 m
in
length, or longer. The relatively short deck slabs 18 facilitate alignment,
since each slab
and its connections and rail support elements can be individually aligned
without affecting
the alignment of any other slab 18; it is much easier to align fewer elements
over a shorter
length of a deck slab 18 than to have to align all of the elements together on
a relatively
lengthy top flange 28 of girder 26. By contrast to the girders 12, girders 26
are typically
no more than about 20 to 30 m in length.
Finally, because the upper surface 90 of the top flange 28 provides a flat bed
for
rail supports 80 on which rails 52 are mounted, and for mounting the central
linear
induction motor (LIM) reaction rail 66, it follows that any creep, shrinkage,
etc. in the
conventional girder 26 affects the geometry and alignment of the guideway slab
(top
flange 28) for supporting the rail 52 and the LIM reaction rail 66. The longer
the girder 26,
the greater the risk of intolerable misalignment of components due to creep or
shrinkage
of the concrete of which girder 26 is formed. By contrast, since the girders
12 and deck
slabs 18 of Figure 4 are preformed, no significant creep or shrinkage problem
arises -
initial misalignment is minimized by the manufacturing procedure followed, and
alignment
of components and of any one deck slab 18 with its neighbours is relatively
easy and
permanent once the slab 18 is positioned in place on the girder 12 supporting
it. The
shorter length of each deck slab 18 relative to the typicall length of the
girders 26 facilitates
alignment; alignment of the deck slabs 18 can be effected one by one, and
alignment of
rail supports, etc. on any one deck slab 18 can be effected separately from
the alignment
on neighbouring deck slabs 18.
The conventional girder/guideway structure 22 of Figure 1 other than the
parapets
43 is cast as an integral unit using an interior collapsible form (not shown)
to define the
interior surfaces of the girder and the undersurface of the rail guideway top
flange 28, as
well as external forms for the undersurface of the girder bottom flange and
the slightly
inclined upright wall (web) surfaces, leaving, however, the entire top surface
90 of the
concrete in the guideway slabs 28 to be hand-finished. The upper horizontal
surfaces of
the parapets 43 of the guideway 22 also have to be hand-finished. Note that
the hand-
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CA 02349315 2001-05-11
finishing of the upper surface 90 of the flat bed is labour-intensive.
Further, because of
the hand-finishing, it is necessary that any protruding connection studs, etc.
be avoided;
no connection element should protrude above the surfiace 90 until after
finishing. This
means that the attachment elements for the rail supports 80 and for the
composite
insulator and bar structures 88 that support LIM rail 66 have to be inset
female
receptacles 50, 84 as illustrated in Figure 1. Eventually, matching male bolts
56, 86 have
to be screwed into the female receptacles 50, 84 respectively. This
combination of male
and female elements is expensive relative to the cost of connecting stud bolts
51, 72 that
could protrude from the upper surfaces 53, 63 of the guideway slab 18 of
Figure 4, in
which stud bolts 51, 72 may be cast and anchored in place when the slab 18 is
formed.
It can also be seen from Figure 1 that the rail support element 80 shown for a
typical portion of the track has to be trapezoidal in tran:>verse section so
as to provide an
upper inclined surface to which the rail 52 may be directly attached, thereby
to cant the
rail. As mentioned previously, canting at 1:20 is conventional to avoid track
hunting by the
carriage wheels on both tangent track (straight track segments) and
superelevated spiral
track (curved track segments). Because of the occurrence of creep, shrinkage,
etc. in the
girder 26 (which includes top flange 28 as the underlying rail support
structure), the initial
mounting of rail support elements 80 for canting the rail cannot be predicted
with
confidence to be acceptable after the concrete has fully set - shims, etc. are
typically
inserted to make the appropriate adjustments during tree post-finishing
alignment stage.
By contrast to the foregoing, the requisite cant for the track support can be
formed
by inclining the upper surfaces 53 of each deck slab 18 (Figure 4).
Furthermore, as the
deck slabs 18 can conveniently be shorter than the giuideway flanges 28
integral with
girders 26, and as the deck slabs 18 can be preform~ed, thereby avoiding
subsequent
creep and shrinkage problems, the initial cant formed in the upper surface 53
of slabs 18
and the initial alignment of rails 52 and rail support elements 55, 74 for the
structure of
Figure 4 require little or no subsequent adjustment following installation of
the slabs 18 on
the girders 12; any adjustment required can be effected for each individual
slab 18 as a
whole when it is mounted on girder 12. Once the adjustment is made, it is
secured by
grouting the connection at grout joints 46.
A further problem with the prior guideway structure of Figure 1 is that the
LIM
reaction rail 66 has to be positioned appreciably above the flat bed surface
90 because
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CA 02349315 2001-05-11
of the required position of the LIM reaction rail 66 relative to the LIM motor
(not shown)
on the underside of the railway carriage. This necessitates that the stud
bolts 86
supporting the LIM reaction rail 66 have to extend appreciably above the upper
surface
90 of the guideway flat bed 28. As there are considerable stresses applied to
the studs
86 as trains pass over the reaction rail 66, either the studs 86 have to be
oversized or
provided with reinforcing sleeves or the like, or else the risk of failure due
to metal fatigue
is higher than would be desired, simply because of the extent of unsupported
protrusion
of the studs 86 above the flat bed surface 90.
By contrast, because deck slabs 18 are individually preformed, and the upper
support surfaces thereof need not be coplanar, a centr<~Ily elevated portion
62 of the slab
18 may be provided on which the LIM reaction rail 66 and its immediate
underpinnings 74
may be mounted, thereby avoiding any need for unreinforced protrusion of stud
bolts 72.
Further, inexpensive stud bolts 72 may be anchored in the concrete of deck
slabs 18
when the slabs 18 are formed, reducing both a component expense and a labour
expense. Further, because of the inherent provision ~of a shoulder 68 on the
elevated
portion 62 of the deck slab 18, no separate initial derailment containment or
limiting device
need be provided for the Figure 4 design, where<~s a separate initial
derailment
containment or limiting device (not shown) may be required for the
conventional Figure 1
design.
Also illustrated in Figure 1 on the parapet 43 are conventional power rails 38
for
delivering electric power to the passing railway carriage's. Typically the
power rails 38 and
associated support structure are provided on one parapet only; the opposite
parapet (not
shown in Figure 1 ) would be a simple concrete structure without any inwardly
directed
supported structure of any sort (compare Figure 4, which so far as the power
rails and
support structure are concerned, may be essentially similar to what is shown
in Figure 1 ).
In Figure 5, a sequence in plan view of three consecutive deck slabs 18A, 18B,
and
18C is shown, slabs 18A and 18C only as fragments. It can be seen that the
rails are
mounted to the track support elements 55 that are bolted to the deck slab 18B
by means
of stud bolts 51. The interconnection between these slabs 18A, 18B, and 18C is
optional;
if the sequence of deck slabs is intended to be an integrated structural
entity, then the
joints between consecutive deck slabs will be relatively strong and rugged,
possibly
involving suitable metal or reinforced concrete interconnection. If
consecutive integrity
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CA 02349315 2001-05-11
merely of the slab surfaces is required, then the joints between consecutive
slabs may
simply be grouted. In the exemplary configuration of Figure 5, a grouted joint
94 is
provided between the ends 43 of consecutive slabs 18.
The schematic slab 18B illustrated in Figure 5 i:; not representative
throughout of
any deck slab that would be actually used. Rather, for the purposes of
illustration, the left-
hand side of the slab 18B illustrates a fairly closely spaced arrangement of
rail support
elements 55, whereas the right-hand side of the view illustrates a more widely
spaced
arrangement of rail support 55. The general principle of rail support is the
same in each
side of the schematic view of Figure 5, but it is to be understood that in a
real guideway,
the rail supports on the left-hand side of the deck slab would match those on
the right-
hand side. In practice, where the track is tangent track (straight), fewer
rail supports 55
will be required at longer interval spacings (as illustratE;d in the right-
hand side of Figure
5). For curved portions of the track, the stresses on the rails are higher and
accordingly
the rail supports 55 will be more numerous and more closely spaced (as
illustrated in the
left-hand side of Figure 5). Further, the overall shape of a deck slab for use
in curved
track (not illustrated) would typically complement the track curvature; the
deck slab ends
43 would in plan view be slightly inclined to follow 'the radius of curvature,
and the
positioning of the rail support elements 55 would accommodate the curvature of
the track.
In practice, assuming that an average rail support spacing for all curved
track regardless
of the degree of curvature would be suitable, it may be possible to cast only
two different
types of deck slab, one for use with tangent track and the other for use with
curved track.
If, however, some adjustment in the number of rail supports for different
degrees of
curvature is considered desirable, or if the sides or ends. of slabs having
different degrees
of curvature require more than one curved slab to be rnanufactured, then three
or more
different deck slab designs with differing rail support spacing and different
side and end
treatment can be provided.
It is also required that each deck slab 18 be firmly fixed to the underlying
girder 12;
for this purpose, rectangular apertures 98 are provided at spaced intervals
along each
deck slab 18. Conveniently, these rectangular apertures may be located between
successive rail support elements 55.
Figure 7 illustrates a suitable means of interconnection between the deck
slabs 18
and the girders 12. Tie groups 102 (see Figure 8), which are bundles of
reinforcing steel
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CA 02349315 2001-05-11
bars (re-bars) tied together, are embedded into the concrete of the top
flanges 34 of the
girder 12 at spaced intervals that match the spacing of i:he apertures 98 on
the deck slabs
18. This of course implies that for curved deck slabs and curved girders, the
spacing will
be closer together than will be the case for tangent track and straight
supporting girders.
Once each deck slab has been set in place and aligned atop a given girder 12,
grout is poured into the apertures 98 to form a grout plug 100 that can be
hand finished
at its upper surface. The grout plug 100 will fill the space between the
underside of the
deck slab 18 and the upper surface 36 (see Figures 3 aind 4) of the upper
flanged portions
34 of the girder 12. The grout plug 100 also surrounds and bonds to the tie
groups 102,
thereby forming a secure composite joint between the deck slab 18 and girder
12. A
portion of the grouted joint 100 may provide a spacing grout layer 46 (Figure
4) to fill any
gaps between the underside of the deck slab 18 and the upper surface 36 of the
adjacent
girder 12. This space will be expected to vary somewhat from point to point
underneath
the deck slab 18 in order to accommodate whatever adjustments are required to
bring the
deck slab 18 into its final alignment. Once the grout plug 100 sets, the final
track support
surface alignment is preserved on a permanent basis.
Figure 6 illustrates a portion of the grouted joint 94 between two adjacent
deck slab
members 18. To provide structural continuity, protruding reinforcing steel
bars 95 can be
embedded into the concrete of the ends 43 of the deck slabs, which when
grouted form
a reinforced composite joint.
Figure 9 illustrates schematically forms for the manufacture of a pair of deck
slab
elements. It is efficient and convenient to manufacture the deck slab elements
in pairs,
as illustrated in Figure 9, so that the pouring of concrete into the forms is
efficient and so
that the two concrete filled forms balance one another, Eliminating the risk
of toppling and
avoiding the need for any special support, other than a longitudinal divider
between the
forms.
Specifically, a longitudinal central form support panel or truss 106 is
centrally
mounted on a base 108 for separating a pair of balanced forms, each generally
indicated
as 110, from one another. Each form structure 110 may be divided into a top
form 112
and a bottom form 114 defining generally the top and bottom surface shapes for
the
eventual deck slab 18 to be manufactured. In other words, the hollow cavity
116 within
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CA 02349315 2001-05-11
each of the form structures 110 conforms in its internal surfaces to the
intended external
surfaces to be formed on the deck slab 18. For simplification, some of the
details of the
surface configuration of deck slab 18 have not been illlustrated in Figure 9.
The line of
separation between top form 112 and bottom form 114 (the adjectives "top" and
"bottom"
being applicable to the intended top surface and bottom surface respectively
of the
eventual deck slab 18) is in the form designer's discretion, but should be
chosen to
facilitate easy separation of the bottom form from they top form once the
concrete has
been poured and has set within the form structure 110.
In order to pour concrete into the cavity 116, a pouring portal 120 is
provided atop
each of the form structures 110 and is positioned so that poured concrete will
completely
fill the cavity 116. To facilitate complete filling of the cavity 116 and to
promote stability
of the form structures 110, shims or roller supports or hinges 122 may be
positioned
underneath the lower outer corners of the form structurEa 110 as illustrated.
If hinges are
used along with suitable angled form supports (not shown in Fig. 9), each form
structure
110 may be pivoted about the hinges to assume a generally horizontal
orientation to
facilitate separation and removal of the top form 112 from the bottom form 114
once the
concrete has set. Although the form structures 110 are shown as being slightly
out of
contact with the vertical form support 106 in Figure 9, they may in fact tilt
inwardly
sufficiently that the upper portions thereof make contact with the upper
portion of divider
106.
Since the particular configuration of a given dleck slab 18 will not be
uniform
throughout the guideway but will vary from point to point along the guideway,
depending
upon whether the guideway at a particular location is supporting tangent track
or curved
track, etc., a number of different shapes and configurations of form structure
110 may be
provided to form as many deck slab shapes as are required for any particular
guideway.
Alternatively, individual form structures 110 may be provided with
individually adjustable
means (not shown) for accommodating differences in intended deck slab
configuration.
For most purposes it will probably be desirable to have individual form
structures that do
not require alteration. Therefore, a number of different types of form
structures will, in
most cases, be provided to make possible the manufacture of a number of
different
configurations of deck slab. In the simplest case, as few as two different
deck slabs need
be manufactured, one for curved track segments and the other for tangent track
segments.
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CA 02349315 2001-05-11
Figure 10 is a more detailed exploded view of a suitable support structure for
the
forms and of the individual form components themselves, thereby illustrating a
convenient
and effective implementation in a more detailed fashion of the arrangement
illustrated in
a simpler schematic fashion in Figure 9. Each form structure 110 shown in
Figure 10
comprises a top form 112 and a bottom form 114, as dliscussed with reference
to Figure
9. Again the interior surface 164 of each top form 112 has been somewhat
simplified in
Figure 10; the shape and configuration of the form 112 will of course be
adapted to the
particular top configuration required for each deck slab 18. The top forms 112
are
provided with bolt holes 132 for alignment with mating bolt holes 134 in the
bottom form
114, thereby permitting the forms 112, 114 to be securely bolted together to
enable the
concrete to be poured into the interior cavity 116 formed when the top form
112 and
bottom form 114 are bolted together.
The uppermost surface of each top form 112, as illustrated in Figure 10, is
formed
as a trough 136 into which concrete can be poured. The bottom portion of the
trough 136
is open to the interior of cavity 116 when the forms 112, 114 are bolted
together, thereby
constituting the pouring portal 120, as discussed with reference to Figure 9.
Further, Figure 10 illustrates end trusses 124 each having a base plate 108
and a
vertical central stud 126, along with whatever struts are considered suitable
to the integrity
and required strength of the truss 124. The two studs 1126 also serve as the
vertical end
portions of a rectangular truss 128 extending between and consisting in part
of the end
studs 126 and serving as a suitable specific implementation of the vertically
disposed form
support 106 illustrated in Figure 9.
The end trusses 124 may be provided at their lovuermost end portions with
flanges
166 for attachment to an underlying platform, or the like (not shown), in
order to stabilize
the truss arrangement illustrated.
A jig (not shown) may be provided with the stud k>olts 51, 72 (not shown in
Figures
9 and 10) required to support the rail support elements and the LIM reaction
rail support
elements (if the railway is of the LIM type). The jig may be aligned with and
positioned
against the inside upper form 112 so that these stud bolts 51, 72 project into
the interior
space that will be filled by the concrete. The stud bolts 51, 72 can be
temporarily retained
in place using a pair of nuts, one on the interior surface of the forming wall
and the other
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CA 02349315 2001-05-11
on the exterior surface of the forming wall. When the concrete has set, the
nuts on the
exterior portions of the forming wall can be removed, leaving the stud bolts
51, 72
projecting. The forms can then be simply pulled away 'from the set concrete,
leaving the
stud bolts 51, 72 projecting from the concrete surfiaces in the places where
they are to be
located. In order to permit the forms to be readily removed from the parapets
42, the
parapets 42 should be formed with inclined surfaces flaring outwardly from top
to bottom
as perceived in Figure 4. It is usually preferred, again so that the forms may
be readily
removed from the parapet portions of the structure, to use inset female
elements on one
parapet for supporting the electric power delivery rails (as illustrated in
Figure 4).
Positioned on either side of the rectangular truss; 128 are form support ramps
130
that support the form structures 110. Atop the ramps 130 in the vicinity of
their outermost
edges are hinges 138 each including a generally elongate trough or angled form
support
bracket 139 pivotal with the hinges 138. On each support bracket 139 rests the
lowermost
edge 160 of a respective bottom form 114 when the assembled form structure 110
is
positioned atop the associated ramp 130. The concrete is poured into the form
cavity 116
and the concrete permitted to set. When the concrete has set, each form 110 is
tilted and
pivoted away from the rectangular truss 128 so as to lie almost flat on the
ground (or
platform, or as the case may be). The upper form 112 is. provided with
apertured tabs 162
to which grappling hooks (not shown) may be attached for separating and
removing the
top form 112 from the bottom form 114, once the bolts securing the two forms
112, 114
together have been removed.
The track guideway arrangement and deck slab design illustrated in Figure 11
are
relatively simple and suitable for an elevated railway in which power is
supplied via an
overhead catenary system. The illustration of Figure 11 is schematic only and
omits a
number of components that would be found in such arrangements, including
especially
the connectors for connecting the deck slabs 118 to the girder 12. Most of the
discussion
of Figure 4 is applicable to Figure 11; the main differences are differences
of detail by
reason of the simpler upper surface structure of the deck slab 118 of Figure
11 because
of the absence of an LIM reaction rail and associated LIM-related elements or
support
structure. (Note, however, that power rails could be mounted on the parapets
142 for use
with conventional electric railways in which the power is supplied on such
power rails just
above ground level and returned via the train wheels 1:o the carriage support
rails 152,
which would also serve as return conductors for the elE:ctric circuit.)
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CA 02349315 2001-05-11
The particular deck slab 118 illustrated in Figure 11 is provided with
slightly
elevated integrally formed rail plinths 148 provided with female threaded
receptacles 150.
The upper surfaces 158 of the rail plinths 148 are preferably slightly
inwardly canted
(typically with a 1:20 cant) to avoid "hunting" of the railway carriage wheels
on the rails,
in accordance with conventional design. The arrangement illustrated in Figure
11, like that
of Figure 4, permits the rail support elements 154 to be~ of rectangular cross-
section, and
therefore less costly to manufacture. The structure of Figure 11 differs from
that of Figure
4 in that the elevated concrete plinths 148 serve not only to present an upper
canted
surface for attachment to and support of the rail support elements 154, but
also provide
derail abutments against which the wheels of a derailed train may bear so as
to constrain
sideways motion of a derailed train; the parapets 142 serve as further
protection against
derailment, and provide sound abatement.
For the combined structure of Figure 11, girders 12 and slabs 118 can be of
generally the same length as counterpart elements prEwiously described with
reference
to Figure 4, and can be connected together and groutE:d in essentially the
same way as
discussed previously with reference to Figures 4 and 5.
Variants and alternatives other than those described in the above
specification will
occur to a person skilled in the art, and do not depart from the spirit of the
present
invention. For example, an alternative to the U-shaped .girder element 12 used
to support
the guideway track slabs 18 in the case where the guideway passes through a
tunnel,
such as a continuous foundation slab, is described above, although it is
understood that
further such support variants, possibly including for example steel truss
girders, may be
employed, all of which variants fall within the scope of the present
invention. In a further
example, variants of the particular fittings and attachments described in the
above
specification such as stud bolts 51, 72, and rail support elements 55 may be
alternatively
employed; structures including such alternative components also fall within
the scope of
the present invention. It is understood that the particular embodiments of the
present
inventive railway support structure and associated method and apparatus for
producing
said support structure described in the present specification are exemplary in
nature, and
do not limit the scope of the present invention. The :.cope of the present
invention is
defined in the following claims.
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