Note: Descriptions are shown in the official language in which they were submitted.
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INSTALLATION SYSTEM FOR BRIDGE GIRDERS
This invention relates to an installation system for
bridge girders.
I BACKGROUND OF THE INVENTION
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I Smaller highway bridges are often constructed of
I bridge abutments which are formed on either side of the area
to be spanned together with a precast concrete girder system
which is mounted on the bridge abutments and spans the space
therebetween. Often the bridge girders are formed as
elongate elements of approximately four feet transversed
dimension and these are laid side by side spanning the space
between the bridge abutments for subsequent construction of a
road surface on top of the girders.
The precast concrete girders are formed at a separate
location and are transported by road from the place of
manufacture to the installation site. Bridge girders of this
type can weigh of the order of 40 tons and hence are of
course difficult to transport ancl more difficult to manoeuvre
into place.
The conventional technique for handling the bridge
girders at the installation site is to transport a crane to
the site of a size sufficient to lift and manoeuvre the
girders into position spanning the space between the bridge
abutments. Such a crane is itself heavy and difficult to
-transport by road and extremely expensive to purchase, lease
or maintain. The installation of such bridges at relatively
remote locations is of further expense in view of the costs
involved in leasing or holding the equipment during the
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transportation time.
SUMMARY OF THE INVENTION
It is one object of the present invention, therefore,
to provide an improved system for installation of bridge
girders.
3 According to a first aspect of the invention there is
provided a method for installing a precast concrete bridge
girder for the girder to extend from a first bridge abutment
at one end to a second bridge abutment at a second end of the
girder and to span an area to be bridged, the method
' comprising providing a track girder assembly, a first lifting
~ gantry and a second lifting gantry, the track girder assembly
¦ forming an elongate guide track on which the lifting gantries
~ can run longitudinally of the guide track, mounting the track
i girder assembly so as to span the area to be bridged,
mounting the first and second gantries on the track girter
assembly, transporting the bridge girder to a position with
one end of the bridge girder adjacent one end of the track
girder assembly such that a second end of the bridge girder
is spaced from a second end of the track girder assembly and
aligned therewith, attaching said one end of the bridge
girder to the first lifting gantry to be carried thereby,
moving the bridge girder longitudinally of the track girder
assembly such that said one end is carried by the first
lifting gantry while moving along the track girder assembly,
attaching said second end of the bridge girder to the second
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lifting gantry, moving the first and second lifting gantries
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longitudinally of the track girder assembly while carrying
the bridge girder to positions such that the first and second
ends of the bridge girder are substantially aligned ~ith the
bridge abutments and simultaneously actuating the first and
second lifting gantries to lower the bridge girder onto the
first and second bridge abutments
According to a second aspect of the invention there
is provided a apparatus for installing a precast concrete
bridge girder for the girder to extend from a first bridge
abutment at one end to a second bridge abutment at a second
end and spanning an area to be bridged, the apparatus
comprising a track girder assembly forming a elongate guide
track for spanning between the first and second bridge
abutments, a first lifting gantry and a second lifting gantry
each for mounting on the track girder assembly for movement
longitudinal thereof, each lifting gantry including means for
supporting the bridge girder, ram means for lifting said
support means vertically, and means mounting said track
girder assembly for movement side to side in a direction
generally at right angles to the length of the track girder
assembly.
One embodiment of the invention will now be described
:. in conjunction with the accompanying drawings in which
DESCRIPTION OF THE_DRAWINGS
Figure 1 is a side elevational view of the apparatus
~ for installing a bridge girder according to the present
`~ invention.
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., E'igure 2 is a similar side elevational view showing
an initial step of the installation method using the
apparatus of Figure 1.
Figure 3 is a top plan view of the apparatus as
shown in Figure 2.
Figure 4 is a side elevational view of one of the
lifting gantries of Figure 1.
Figure 5 is a cross sectional view along the lines
5-5 of Figure 4.
Figure 6 irS cross sectional view along the lines 6-6
:~ of Figure 4.
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In the drawings like characters of reference indicate
corresponding parts in the different figures.
DETAILED DESCRIPTION
Referring firstly to Figures 1, 2 and 3, the
apparatus for the installation system comprises a track
girder assembly 10, a first lifting gantry 11, a second
lifting gantry 12, a first sliding support beam 13 and a
second sliding support beam 14, each for supporting a
respective end of the track girder assembly.
The bridge structure includes a first bridge abutment
15 and a second bridge abutment 17 which are built on the
ground surface at a position spaced apart on either side of a
area 17 to be spanned by the completed bridge. The completed
bridge includes a bridge girder 1~ which is mounted upon a
support shelf of the bridge abutments 15, 16 so as to be
supported thereby in a spanning arrangement over the area 17.
In an initial construction step, the bridge abutments
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and 16 are constructed by the insertion of supporting
piles and the casting of the concrete s~ructures forming the
abutments. The precast concrete beams 18 are manufactured in
a conventional process at a manufacturing site and are
transported by transportation truck 19 from the site of
manufacture to the installation location at the abutments 15
and 16. One bridge girder is shown installed at 18 and a
~ second bridge girder 20 is shown in the installation process.
;, The sliding beam supports 13 and 14 are mounted on a
10suitable wooden base which is temporarily laid from the
ground structure onto the top of the abutments to provide a
base structure for receiving the installation system. Each
of the sliding beams 13, 14 includes a base beam 21 on which
is mounted a sliding platform portion 22 which slides
longitudinally of the base beam 21 so as to adjust the
position of the track girder assembly laterally of the
abutments 15 and 16.
The track girder assembly comprises a pair of track
elements 24 and 25 which are arranged in a common horizontal
20plane and extent in parallel spaced relationship across the
area to be spanned and supported upon the platforms 22. The
~ platforms are notched so as to receive the track elements and
;~ hold them at the required spaced location. Each track
element is of the construction as shown best in Figure 5
including a pair of vertical I-beams 26 and 27 which are
connected by a base plate 28 and by a top plate 29 to form an
integral beam of sufficient mechanical strength to carry out
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the functions as set forth hereinafter~
~ Each track element has a length sufficient to extend3 from the abutment 15 across to the abutment 15 and beyond the
abutment 15 to an outer end 71 which is supported in
cantilever arrangement from the two abutments. The track
elements are unconnected apart from three braces 30, 31 and
32 which connect the track elements at a position adjacent a
I centre point of the span between the abutments to hold the
; track elements against relative longitudinal movement or
transverse movement under the heavy loading carried by the
lifting gantry as it moves across the span.
The construction of the lifting gantry is best shown
in Figures 4, 5 and 6 and includes a U shaped base best
visible in Figure 6 having a pair of side beams 33 and 34 and
a cross connecting beam 35. Each of the side beams 33 and 34
carries a pair of rollers 36 and 37 mounted on pillow blocks
38 mounted on an under side of the beam. Roller 36 is
arranged at one end of the beam and a roller 37 is arranged
¦ at the opposed end of the beam. Each of the rollers
comprised a cylindrical body having a width just greater than
the width of the respective track element and a pair of
flanges 39 and 40 at ends of the cylindrical body forming the
roller so as to hold the roller in position on the top flange
29 of the track element. Thus the base can roll along the
track girder assembly for transportation of the lifting
gantry from the open outer end towards the abutment 16.
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~ On top of the base is provided a generally pyramid
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shaped support frame 41. The support frame includes two main
vertical beams 42 and 43 each mounted on a respective side
frame element and extending vertically upwardly therefrom at
a central position thereon. The vertical beams 42 and 43 are
braced by a pair of inclined beams 44 and 45 on the side
frame 33 and inclined beams 46 and 47 on the side frame 34.
At the top of the frame structure, a transverse beam 48
interconnects the incline beams 44 and 45 and a cross beam 50
extends across the top between the two side frames.
Lif~ing frame 50 comprises a cross-beam structure 51
including a pair of spaced beams 52 and 53 which are arranged
forwardly and rearwardly respectively of the vertical post
42, 43. The cross beam 51 carries a sliding sleeve 54 which
can be moved across the width of the lifting gantry by a
hydraulic cylinder 55. The sleeve 54 carries a pair of
U-shaped supports 56 and 57 to which the girder 18 can be
attached by cables 58.
The cross beam 51 is supported at each end by an
inverted U-shaped structure 56 including a cross member 59
and a pair of depending legs 60 each of which is attached to
an end of a respectiv~ one of the beams 52 and 53. The cross
members 59 at each end of the lifting frame are attached to
the top end of a cylinder 62 which is a multi-stage cylinder
acting to lift the lifting frame by distance of the order of
ten feet to provide sufficient liEting action for the
installation process.
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;~ Turning again to Figures 1, 2 and 3, firstly the
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;!" track girder assembly is moved into position across the area
" to be spanned by a suitable technique. One example, the
track elements are moved across by pushing a first track
element part way across and then sliding a second track
~;,i element over the first. The track elements are relatively
light in comparison with the bridge girders and therefore can
be handled relatively easily by the type of crane available
on vehicles for moving equipment and similar items. Once the
track girder assembly is in place, the lifting gantries are
~ 10 positioned on top of the track girder assembly for rolling
'~ movement along the top surface of the track elements.
The girder to be installed as indicated at 20 is then
brought into position on the transport vehicle 19. The track
elements are spaced by width sufficient to receive the rear
transportation dolly 70 of the transport vehicle between the
track elements so that the girder 20 is moved to a position
between the cantilevered end 71 of the track assembly. The
lifting gantries are then moved into position on top of the
portion of ~he girder 20 and the outer one of the lifting
gantries is connected to the girder while in a raised
position or just below the fully raised position and then the
lifting gantry is actuated to lift to the top of the raised
position to lift -the girder away from the dolly 70. The
dolly 70 can then be moved out of the area. The tractor unit
of the transportation vehicle is then backed up pushing the
lifting gantry 11 and the girder across the track girder
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assembly until the forward end of the girder 20 is positioned
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between the ends 71 of the track elements. The lifting
3 gantry 12 is then operated to lift the forward end of the
girder so that the girder is then wholly carried on the
lifting gantries. The girder on the gantries are then moved
again in a longitudinal direction to take up a position
;~ directly overlying the abutments as shown in Figure 1. In
this posi~ion the lifting gantries can be lowered by
retracting the cylinders 62 to lower the girder into position
on the abutment. If necessary, if the amount of movement is
greater than the stroke of the cylinder 62, it is possible to
block up the girder at each end and then to restart the
stroke by re-engaging the girder with longer cables.
;i~ In order to allow the girder to be lowered through
the area between the track elements, it is necessary
temporarily to release the braces 30, 31 and 32 and to pivot
these to one side to allow the girder to pass therebetween.
The wide spacing between the track elements allows at least
one second girder to be moved into place without shifting the
!.dd track elements. The can be effected by the transverse
movement of the lifting frame. Once the full extent
available between the track elements has been utilized, it is
necessary to move the track elements trasversely by the
sliding platform 22.
Since various modifications can be made in my invention as
hereinabove described, and many apparently widely different
embodiments of same made within the spirit and scope of the
claims without departing from such spirit and scope, it is
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intended that all matter contained in the accompanying
specification shall be interpreted as illustrative only and
not in a limiting sense.
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