CA1054318A - Bridge structure - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The disclosure relates to a portable bridge in the form of a permanently assembled unitary structure.
The structure has a base frame which includes at least two main longitudinal supporting members extending from end to end of the structure in spaced parallel positions.
These members have opposite end portions adapted to rest on supporting surfaces at opposite sides of an area spanned by the bridge in use. The frame also includes two trans-verse members which extend between adjacent end portions of the respective longitudinal members at opposite ends of the bridge structure. The transverse members are ac-cessible from externally of the bridge structure and are adapted to provide attachment points for facilitating transportation and/or securing of the structure in a position of use. The structure also includes a deck pro-viding a roadway surface which extends longitudinally 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 longi-tudinal members of the base frame and are supported on and coupled to the longitudinal members.

Description

~)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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~L~S~3~8 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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~, 1~5~ 8 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~
: .: , ~ 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 :
that in this embodiment the frame has four main longitudinal supporting members which run the whole length of the bridge ::
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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43~8 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 :~L0543~8 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 ~ ~ .
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 ' - 6 - ~

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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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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 -`
, 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 i :
; 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 , ""' 1~5431~

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 ~` _ g _ .' ' ';

, 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 : .:
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 .:
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.

- - - , - . ~ . . , ~0543~8 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 .. ' ~' 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 :. , .
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 .., centre of gravity results from the fact that the base frame ,: . ~ .. ..
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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Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A portable bridge in the form of a permanently assembled unitary structure comprising:
a base frame including at least two main longi-tudinal supporting members which extend from end to end of the structure in spaced parallel positions and which have opposite end portions adapted to rest on supporting sur-faces at opposite sides of an area spanned by the bridge in use, and two transverse members extending between ad-jacent end portions of the respective longitudinal members at opposite ends of the bridge structure, said transverse members being accessible from externally of the bridge struc-ture and being adapted to provide attachment points for facilitating transportation and/or securing of the structure in a position of use; and, a deck providing a roadway surface which extends longitudinally 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, said members extending transversely of the main longitudinal members of the base frame and being supported on and coupled to said longitudinal members.

2. A bridge as claimed in claim 1, wherein said base frame includes four main longitudinal supporting mem-bers arranged in pairs adjacent respectively opposite sides of the frame.

3. A bridge as claimed in claim 2, wherein said main longitudinal supporting members are in the form of I-beams, and wherein the members in each pair are welded together to form a single box-section unit.

4. A bridge as claimed in claim 2 or 3, wherein said base frame further comprises an additional main longitudinal supporting member disposed centrally of said base frame.

5. A bridge as claimed in claim 1, wherein said main longitudinal supporting members of the base frame are I-beams having upper and lower horizontal flanges, and wherein said main deck members are supported on the upper flanges of said I-beams and comprise a series of I-beams spaced from one another along said longitudinal mem-bers of the base frame and welded to said members, and a series of timber members disposed between said I-beams and mechanically attached to the longitudinal members of the base frame.

6. A bridge as claimed in claim 5, wherein the deck further comprises at least one layer of timber planking secured to the timber main deck members.

7. A bridge as claimed in claim 1 wherein the deck further comprises side rails which extend longitudinally of the deck at respectively opposite sides thereof, and each of which comprises upper and lower longitudinal mem-bers and intermediate members extending between said upper and lower members, said lower members being coupled to end portions of the main deck members.

8. A bridge as claimed in claim 7, further comprising, at the inner side of each of said rails, a wheel guard com-prising a protective member which extends along the inner side of said rail, and means supporting said member at an elevated position above said roadway surface of the deck and below the upper longitudinal member of the side rail.

9. A bridge as claimed in claims 5 and 8, wherein said protective member of each wheel guard is made of timber of relatively substantial dimensions, and wherein said sup-porting means comprises a plurality of blocks spaced along said protective member and disposed between the member and appropriate ones of said I-beam deck members, whereby the protective member is supported on said I-beam deck members with the inter-position of said blocks, and wherein the wheel guard further comprises, at the position of each of said blocks, a U-bolt which extends around said I-beam deck member and clamps the protective member and block thereto.

10. A bridge as claimed in claim 1, wherein said main longitudinal supporting members of the base frame are in the form of I-beams having upper and lower flanges connected by a generally vertical web, and wherein said transverse mem-bers of the base frame extend through the webs of said I-are in the form of metal pipes welded to the main longitudinal members, said base frame further comprising a plurality of diaphragm members extending transversely of the frame between the webs of the main longitudinal supporting members and welded to said webs.