Note: Descriptions are shown in the official language in which they were submitted.
~)543~8
This invention relates to a portable bridge struc-
ture.
In the fields of civil engineering, oil explora-
tion and the like, situations are often encountered in which
a temporary bridge is required across, sa~, a river, a ra-
vine, or other topographical feature. Probably the most
well known type of bridge capable of being used in such si-
tuations is the "Bailey" bridge. This type of bridge is
designed to be assembled on site from a collection of inter-
changeable panels. The problem is that assembly and disas-
sembly of the panels is a time consuming operation requiring
a substantial labor force. In a typical case, assembly or
disassembly of a Bailey bridge may take two days.
Another example of a prior art portable bridge
i~ structure is shown in United States Patent No. 2,339,098
to Harold Nagin. In that case, a bridge for accommodating
road vehicles comprises two parallel bridge units (one for
supporting the wheels at each side of the vehicle), each
made up of vertical straps and cross-beams fitted together ` ~ " `
~ 20 in interlocking relationship. Here again, the structure
-i is designed to be assembled on site, which would be a time
consuming and labor intensive operation. ;~An object of the present invention is to provide
a bridge which can be readily transported from site to site
and which can be erected or removed in minimum time.
~ According to the invention the bridge is in the
;`i form of a permanently assembled unitary structure which
` includes a base frame having at least two main longitudinal
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supporting members extending from end to end of the struc-
ture in spaced parallel positions. The members have opposite
end portions adapted to rest on supporting sur~ace5 at op-
posite sides of an area spanned by the bridge in use. The
Erame also includes two transverse members which extend be-
tween adjacent end portions of the respective longitudinal
members at opposite ends of the bridge structure. The trans-
verse members are accessible from externally of the brldge
structure and are adapted to provide attachment points for
facilitating transportation and/or securing of the structure
in a position of use. The bridge structure also includes
a deck providing a roadway surface which extends longitu-
dinally of the bridge structure from end to end thereof and
which includes a plurality of main deck members capable of
supporting loads to be carried on the bridge. The main deck
- members extend transversely of the main longitudinal members
~ of the base frame and are supported on and coupled to said
`i
, longitudinal members.
In order that the invention may be more clearly
understood, reference will now be made to the accompanying
drawings which illustrate one embodiment thereof by way of
example, and in which:
Fig. 1 is a perspective view of a bridge structure
according to the invention shown in use; -~
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Figs. 2 and 3 are a side view and a plan view
respectively of the bridge structure shown in Fig. l;
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Figs. 4 and 5 are a side view and a plan view -~
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respectively taken on lines IV-IV and V-V of Fig. 3; and
Fig. 6 is a partial longitudinal sectional view
on line VI-VI of Fig. 5.
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Referring first to Fig. 1, a bridge is generally
indicated at 20 and is shown in a typical environment in
which it spans a river and rests on supporting surfaces 22
and 24 formed hy parts of the river banks. ~ truck is shown
at 26 crossing the bridge. Access ramps (not shown) will be
provided on both river banks at the ends of the bridge, for
example, as indicated in ghost outline at 28. These ramps
will be constructed from naturally available material such
as gravel, stones and earth. In a situation in which the
brid~e is intended to be used on a permanent basis, access ~
ramps of concrete or the like may be provided. ! ',.', ',
As indicated previously, the brid~e is in the form
of a permanently assembled unitary structure which can be
delivered to the site ready to be used. Referring now more
particularly to Fig. 2, the structure includes a base frame
` generally denoted 30, and a deck 32 supported on the base
frame. Frame 30 includes two outer main longitudinal sup~
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~ porting members 34 and 36 (see Fig. 3) which extend from
; end to end of the structure in spaced parallel positions.
Spaced inwardly from each of these members is an additional `~
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main longitudinal supporting member; these two additional
members are indicated at 38 and 40. Thus, it will be seen
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that in this embodiment the frame has four main longitudinal
supporting members which run the whole length of the bridge
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structure. The four members 34, 36, 38 and 40 are essentially
identical and are in the form of I-section steel girders.
~ The girders are all visible in section in Figs. 4, 5 and 6
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and it will be seen that each girder has flat horizontal
top and bottom flanges which are denoted by the suffixes
a and b respectively. Referring back to Fig. 2, it will
be seen that, at each end, the bottom flange of each girder
(as exemplified by flange 36a) is angled upwardly with re-
spect to the horizontal to in effect form ramp-like edges
at both ends of the girder. This is accomplished by cut-
ting and welding the girder as will be apparent to a per-
son skilled in the art.
ln Frame 30 also includes two transverse members 42
and 44 which extend between adjacent end portions of the
respective pairs of longitudinal members 34, 38 and 36, 40.
As can best be seen in Fig. 4, each of these transverse
members is in the form of a circular section metal pipe
which passes through and is welded into complementary
; openings in the vertical webs of the four longitudinal mem-
bers 34, 36, 38 and 40. The ends of the pipes 42 and 44
project outwardly beyond the outer main longitudinal mem-
bers 34 and 36 and are fitted with end caps denoted 42a and
42b in the case of pipe 42 and 44a and 44b in the case of `
pipe 44. It will be seen that the pipes 42 and 44 are ac-
cessible from externally of the bridge structure and it will
be appreciated that they provide attachment points for fa-
cilitating transportation and/or securing of the bridge
structure in a position of use. For example, referring
back to Fig. 1, it will be seen that pipe 42 is visible
at one end of the structure and that cables 46 and 48 have
been attached to the pipe and to stakes at 50 and 52 driven
into the ground adjaceni the bridge. Similar cables are
provided at the other end of the bridge but are not visibie
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in Fig. 1.
The pipes 42 and 44 are also used during transpor-
tation of the bridge. Thus, the bridge will normally be
transported from cite to cite on a low loader type of trai-
ler. Winch cables will be attached to the appropriate one
- o the two pipes 42 and 44 for pulling the bridge onto and
off the low loader. Also, suitable restraining means will
be provided on the low loader for holding the bridge in
place during transportation. In this connection, it will
be appreciated that the fact that the lower flanges of the ;
main longitudinal members of frame 30 are angled upwardly ~ -
adjacent their outer ends as discussed above will facilitate
sliding movement of the bridge over a ground surface during
~ loading, unloading and positioning of the bridge.
i Thus, the longitudinal members in effect form skids for
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sliding over a ground surface.
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Referring back to Figs. 2, 3 and 5, frame 30 is
completed by diaphragm members which extend between the main
longitudinal members as inaicated generally at 54, 56 and 58
in Fig. 2. Members 56 and 58 are also visible in Fig. 3 and
member 56 is shown in more detail in Fig. 5. This view will ~ ~ `
now be described as representative of all three of the dia~
` phragm members. Member 56 is in the form of an I-section
steel girder cut into three parts, denoted 56a, 56b and 56c,
which parts are welded between the longitudinal members 34,
36, 38 and 40 of frame 30. The parts of member 56 are a-
ligned with one another to in effect form a single struc-
tural member as can be seen as Fig. 3. Plates 60 and 62
(Fig. 5) are welded into the outer channels of the outer
``~ 30 members 34 and 36 to form web stiffeners and are aligned
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with member 56. The other two diaphragm members 54 and 58
are essentially the same as member 56 and will not therefore
be described separately.
The deck 32 of the bridge structure is supported
on ~rame 30 and provides a roadway surface 64 (Fig. 1) which
extends longitudinally of the bridge structure from end to
end thereof. Deck 34 includes a plurality of main deck
members capable of supporting loads to be carried on the
bridge, which members extend transversely of the main longi- ~ -
tudinal members of frame 30 and are coupled to those members.
Thus, referring primarily to ~ig. 3, the main deck members
include a first series of I-section steel girders generally
indicated at 66 and a second series of timber main deck
members generally indicated at 68. In Fig. 3, portions of
; the deck have been cut away to show the various layers which `
` make up the structure of the deck. Thus, at the right hand
portion of Fig. 3, only the I-section members 56 are shown ~
in order to facilitate illustration of frame 30. Some of ~ -
the timber main deck members 68 are visible in the centre ;'
region of Fig. 3 but it will be appreciated that these mem-
bers in fact extend over the whole length of the deck. The `
I-section members 56 are spaced equally along the main longi-
, tudinal members of frame 30 and are welded to those members
while the timber deck members 68 are arranged in pairs be-
tween each pair of members 66. The timber members 68 are
attached to the main longitudinal members by J-shaped bolts
~ 70 (see Fig. 5) which pass through openings in the members 68
`~ and which have curved lower end portions engaged around the ;~
top flanges of the main longitudinal members of frame 30 as
shown in Fig. 5. ~
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~iD543~8 ~
It will be seen from the dxawings that the main
deck rnembers 66 and 68 project outwardly beyond the outer
longltudinal members 3~ and 36 of frame 30 so that the deck
overhangs the frame at the sides. ~t its outer sides, the
deck includes side rails generally indicated at 72 and 74.
Referring to Fig. 2 by way of example side rail 72 includes
upper and lower horizontal members 76 and 78 respectively
fo box-shape in cross-section. Members 78 is in fact welded
to the outer ends of the I-beam main deck members 66 as can
best be seen in Figs. 4 and 5. The rail is completed by
; intermediate members generally denoted 80 which extend be-
tween the horizontal members 76 and 78 in an alternating
; 45 sequence as shown. The members 80 are also of box-
section steel. Side rail 74 is essentially the same as
rail 72 and will not therefore be described in detail. ~
Referring now to Figs. 5 and 6, wheel guards ;
generally denoted 82 and 84 are provided at the inner sides
of the respective rails 72 and 74. Part of wheel guard 84
is shown in detail in Fig. 6. The wheel guard is made up ~ ~
20 - of a length of timber 86 supported on wooden blocks, two of -`
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which are indicated at 88 and 90, at a spacing above the main
deck members 66 and 68. In fact, it will be seen that the
` blocks are supported on two of the I-beam main deck members -~
66 and that the length of timber 86 is held in place by U-
bolts, two of which are indicated at 92 and 94 which extend
around the appropriate I-beams. The limbs of each U-bolt
project upwardly through openings in the length of
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; timber 86 and are fitted with nuts for in effect
clamping the timber 86 to the relevant deck member
66 with the inter-position of the relevant wooden
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block. Wheel guard 82 is essentially the same as guard
84 and will not therefore be described in detail. It will
of course be appreciated that the purpose of the wheel guards
is to prevent damage to a vehicle and/or to the side rails 72
and 7~ of the bridge due to a vehicle coming into contact
with the rails.
Referring to Figs. 4 and 5, it will be seen that
two layers of timber decking boards extend between the
wheel guards 82 and 84. The boards in the bottom layer are
indicated at 96 and are laid directly on the maln deck mem-
bers 66 and 68. These boards run longitudinally of the deck
as can be seen in Fig. 3 and are nailed to the wooden deck
members 68. The boards in the upper layer are indicated at
98 and extend transversely of the deck as can also be seen
in Fig. 3. These boards are nailed to boards 96. Finally,
two running strips indicated at 100 are provided on top of
the boards 98. Each strip is made up of a series of boards
laid side by side and extending longitudinally of the deck
32. l'he strips are positioned generally where the wheels
of a vehicle crossing the bridge would run and are intended
to provide increased wear resistance at those locations.
As indicated previously, the bridge provided by
the invention is in the form of a permanently assembled
unitary structure which can be readily transported from place ~
` to place and elected or removed in a minimum of time. It is ~ -
anticipated-that the bridge will be factory manufactured and
will not require any on site assembly. As indicated pre-
; viously, it is anticipated that the bridge will be trans-
ported from site to site on a low loader or other road ve-
` 30 hicle. At the site, the bridge will be hauled from the
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1~5~318
vehicle using, for example, a winch or a truck or other
vehicle attached to one of the pipes 42 or 44 of the bridge
by a cable. The bridge can then be positioned across the
~iver or other area to be spanned in a variety oE ways.
For example, a truck or other vehicle on the other side
of -the river can be employed to simply drag the bridge across.
A crane, helicopter, barge boat or other vehicle can alter-
natively be used, eg. in a situation in which access to the
other side of the area to be spanned is not feasible.
It is anticipated that the bridge will be made
available in a variety of different span lengths according
to requirements. For example, the bridge shown in the
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drawings is designed primarily for a 60 ft. span although
similar bridges in, say, 50 ft., 40 ft. and 30 ft. lengths
may be made available. Conversely, longer span bridges may
' also be built within the broad scope of the invention.
It should also be noted that other modifications
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are of course possible within the broad scope of the inven-
tion. For example, although in the bridge shown in the
drawing, the base has four main longitudinal members, there ; ;~
is no limitation to this particular arrangement. In the ~-minimum case, two longitudinal members could be provided.
In another case, an additional central longitudinal m~er oould be
employed. The members need not necessarily be I-section.
-` Box-section members could be used in an alternative embodi-
ment. In fact, one possible modification of the bridge
shown in the drawings would be to provide longitudinal
;` members in pairs as shown, although somewhat closer together, `
and weld the members in each pair together so as to in effect
form a box-section structure. An additional central longi-
tudinal member could then be provided if required.
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Similarly, the pipes 42 and 44 which provide the
anchorage points for the bridge could be of different form
and need not be of circular sllape in cross--section. Other
dctail differences are that the form of the side rails 72
and 74 may vary. For example, vertical upright intermediate
members could ~e used in place of the inclined members 80. ~
Another possible mod;Eication would be to omit the upwardly i
angled bottom flange at each end of each longitudinal member
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of frame 30.
In regard to the deck of the bridge, any appro-
priate deck covering material may be employed. For example,
iron plates, plywood, mesh structures (eg. expanded aluminum)
could be used to provide a roadway surface. In this con-
nection, it is to be noted that the term "roadway surface"
is intended to include any surface over which vehicles and/
or pedestrians can travel. Thus, the bridge structure could
be used solely as a pedestrian bridge.
` It should also be noted that the wheel guards ~ ;
described with reference to the deck of the bridge are to be
~- 20 regarded as optional, even where the bridge is intended for
vehicular traffic.
It should finally be noted that the bridge shown
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in the drawings has a relatively low centre of gravity,
` which allows the deck to overhang the sides of the base
` frame, as can best be seen in Figs. 4 and 5. This low
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centre of gravity results from the fact that the base frame
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30 of the bridge structure has a relatively low overall
` height. The overhanging deck allows a relatively wider
roadway surface without requiring an overly bulky base
frame.
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