MODULAR BRIDGE, A BRIDGE MODULE FOR A MODULAR BRIDGE, AND METHODS FOR ASSEMBLY

Abstract

A modular bridge is formed from a plurality of bridge modules (4), the bridge (2) having a longitudinal direction along the spanning direction and including: a first longitudinal compression member (11,13, 70) that is, in use, at an upper part of the bridge cross-section; a second longitudinal compression member (9, 72) that is, in use, at a lower part of the bridge cross-section; a structural lateral element (9) for forming a deck of the bridge or for supporting deck elements of the bridge; a shear element (14, 16) for carrying a shear load; and a tension member (6) applying a compressive force to one of the longitudinal compression members (1,13, 70); (9, 72) such that when in use the other of the longitudinal compression members (1,13, 70); (9, 72) forms a main compression element for the bridge (2) and the tension member (6) forms a main tension element for the bridge (2). The bridge modules (4) form segments of the length of the bridge (2) and each bridge module (4) is of a one-piece construction, this single piece including: a segment (10, 12) of the first longitudinal (1) compression member of the bridge; a segment (8) of the second longitudinal compression member of the bridge; a segment (8) of the structural lateral element; and a segment (14, 16) of the shear element; and the bridge modules being arranged to support a portion of the tension member (6).

Claims

1.-52. (canceled)

53. A modular bridge formed from a plurality of bridge modules, the modular bridge having a longitudinal direction along the spanning direction and including: a first longitudinal compression member that is, in use, at an upper part of the modular bridge cross-section; a second longitudinal compression member that is, in use, at a lower part of the modular bridge cross-section; a structural lateral element for forming a deck of the modular bridge or for supporting deck elements of the modular bridge; a shear element for carrying a shear load; and a tension member applying a compressive force to one of the longitudinal compression members such that when in use the other of the longitudinal compression members forms a main compression element for the modular bridge and the tension member forms a main tension element for the modular bridge; wherein the bridge modules form segments of the length of the modular bridge and each bridge module is of a one-piece construction, this one-piece construction comprising: a segment of the first longitudinal compression member of the modular bridge; a segment of the second longitudinal compression member of the modular bridge; a segment of the structural lateral element; and a segment of the shear element; and the bridge modules being arranged to support a portion of the tension member; wherein the bridge modules are formed from a composite material and are molded in one piece; and wherein the composite material is a fiber reinforced resin.

54. The modular bridge of claim 53, wherein the bridge modules are coupled to one another by one or more shear transfer joint(s).

55. The modular bridge of claim 53, wherein the shear transfer joints are connectors, each of the connectors comprising: a core to be received within recesses at concave sides of a pair of formations in adjacent bridge modules; wherein there is a mechanism for compressing the formations of the bridge modules against the core.

56. The modular bridge of claim 55, wherein each of the connectors comprises two cup-shaped members for engaging protrusions at convex sides of the pair of the formations of the two bridge modules such that the concave sides of cup-shaped members face the core.

57. The modular bridge of claim 55, wherein each of the connectors comprises a coupling mechanism for compressing the formations against the core, and wherein the core comprises a through-hole and the coupling mechanism comprises a local tension member for extending through the through-hole and the formations, the local tension member being adapted to apply a compressive force to compress the formations against the core.

58. The modular bridge of claim 53, wherein there are two symmetrically-arranged tension members and each tension member applies compression to the longitudinal compression member of the modular bridge.

59. A bridge module for a modular bridge, the modular bridge having a longitudinal direction along the spanning direction, the bridge module being of one-piece construction and forming a segment of the length of the modular bridge; wherein the one-piece construction includes: a segment of a first longitudinal compression member of the modular bridge; a segment of a second longitudinal compression member of the modular bridge; a segment of a structural lateral element of the modular bridge; and a segment of a shear element of the modular bridge; and the bridge module being arranged to support a portion of a tension member; such that when multiple bridge modules are assembled they will form the modular bridge having the first longitudinal compression member that is, in use, at an upper part of the modular bridge cross-section; the second longitudinal compression member that is, in use, at a lower part of the modular bridge cross-section; the structural lateral element for forming a deck of the modular bridge or for supporting deck elements of the modular bridge; and the shear element for carrying a shear load; and such that the tension member, when tensioned, will apply a compressive force to one of the longitudinal compression members with the tension member forming a main tension element for the modular bridge and the other of the longitudinal compression members forming a main compression element for the modular bridge; wherein the bridge modules are formed from a composite material and are molded in one piece; and wherein the composite material is a fiber reinforced resin.

60. The bridge module of claim 59, wherein the segments of the first and second longitudinal compression members are formed integrally above and below the segment of the shear element and the segment of the structural lateral element is formed integrally adjacent to the segment of one of the longitudinal compression members.

61. The bridge module of claim 59, wherein there are pairs of first and second longitudinal compression members with a pair of segments of the two second longitudinal compression members formed integrally at either side of the segment of the structural lateral element, a pair of segments of two shear elements formed extending in a direction away from a plane of the segment of the structural lateral element with each shear element formed integrally with one of the pair of segments of the two second longitudinal compression members, and a pair of segments of the two first longitudinal compression members formed integrally with the two shear elements at a location placed away from the plane of the segment of the structural lateral element.

62. The bridge module of claim 59, wherein the molding of the module is designed with areas of increased strength and stiffness to form the segments of the longitudinal compression members.

63. The bridge module of claim 59, wherein the modules have side parts comprising side panels and side-rails, wherein the side panels generally form the segments of the shear elements and the side rails generally form the segments of the upper longitudinal compression members.

64. The bridge module of claim 59, wherein the segments of the shear elements are textured or perforated to provide a visible pattern.

65. The bridge module of claim 59, wherein the bridge module(s) comprise flanges at their longitudinal ends for engaging with corresponding flanges of adjacent bridge module(s).

66. The bridge module of claim 65, wherein the flanges include formations for receiving complementary shaped cores of connectors.

67. A method of assembly for a modular bridge, the method comprising: providing a plurality of bridge modules, each bridge module being of a one-piece construction and configured to form a segment of a length of the modular bridge; wherein the one-piece construction includes: a segment of a first longitudinal compression member of the modular bridge; a segment of a second longitudinal compression member of the modular bridge; a segment of a structural lateral element of the modular bridge; and a segment of a shear element of the modular bridge; aligning the plurality of bridge modules adjacent one another to form the modular bridge having the first longitudinal compression member that is, in use, at an upper part of the modular bridge cross-section, the second longitudinal compression member that is, in use, at a lower part of the modular bridge cross-section, the structural lateral element for forming a deck of the modular bridge or for supporting deck elements of the modular bridge, and the shear element for carrying a shear load; fitting a tension member to the bridge modules; and tensioning the tension member so as to apply a compressive force to one of the longitudinal compression members with the tension member configured to form a main tension element for the modular bridge and the other of the longitudinal compression members configured to form a main compression element for the modular bridge; wherein the bridge modules are formed from a composite material and are molded in one piece; and wherein the composite material is a fiber reinforced resin.

68. The method of claim 67, further comprising coupling the bridge modules together with shear joints

69. The method of claim 67, further comprising assembling the bridge modules together away from an installation location for the modular bridge in one piece or in sections, then maneuvering them to the installation location before fitting and tensioning the tension member.

70. The method of claim 67, further comprising joining the aligned bridge modules to one another; and then later positioning the joined bridge modules in their final position by maneuvering the joined modules by crane or by pulling or pushing the joined modules across the required span.

71. The method of claim 67, further comprising: joining the aligned bridge modules to one another; and then later positioning the joined bridge modules in a final position by maneuvering the joined modules by crane or by pulling or pushing the joined modules across the required span; wherein positioning the joined bridge modules comprises: anchoring a guide tension member at suitable a location near the required bridge location; engaging the joined bridge modules with the guide tension member; sliding the joined bridge modules along the guide tension member from the other longitudinal side of the final position of the modules into their final position.

72. The method of claim 67 comprising: joining the aligned bridge modules to one another; and then later positioning the joined bridge modules in a final position by maneuvering the joined modules by crane or by pulling or pushing the joined modules across the required span; wherein positioning the modular bridge may comprise jacking the joined bridge modules from one longitudinal side of the modular bridge to the other by pushing it out over the required span whilst the modular bridge supports its own weight in cantilevered fashion.

Description

[0065] Certain preferred embodiments of the present invention will now be described in greater detail by way of example only and with reference to the accompanying drawings, in which:

[0066] FIG. 1 is a perspective view of a modular bridge;

[0067] FIG. 2 is a perspective view of a bridge module of the modular bridge;

[0068] FIG. 3 is a side view showing a worker moving the bridge module;

[0069] FIG. 4 is a side view showing a bridge module for a modular bridge showing stiffened regions;

[0070] FIG. 5A to 5C show alternative webbing arrangements for side panels of the modular bridge;

[0071] FIG. 6 shows a first method of installing the modular bridge;

[0072] FIG. 7 shows a second method of installing the modular bridge;

[0073] FIG. 8 is a sectional view showing a connector for use as a shear joint for connecting two bridge modules of the modular bridge.

[0074] FIG. 1 shows a modular bridge 2 constructed from a plurality of bridge modules 4 (shown individually in FIG. 2). The modular bridge 2 is constructed by abutting the bridge modules 4 in a longitudinal direction (i.e. the direction in which the bridge 2 spans) and post-tensioning them on-site using two tendons (also referred to as tension members) 6.

[0075] The bridge modules 4 themselves are formed off-site. They have a one-piece construction and are formed in a single moulding out of a composite material. All of the mid-span bridge modules 4 (the bridge modules 4 not at the very ends of the bridge) share an identical mould tool, which reduces their manufacturing cost. Exact bridge spans can then be created by putting an end stop into the standard mould to make shorter bridge modules 4.

[0076] For example, in the present embodiment, the mid-span bridge modules 4 are manufactured with a longitudinal length of about 1 meter along the span (this is a nominal length which could be varied if required). A 20.5 meter bridge could then be produced using nineteen standard 1-meter bridge modules 4 and two custom-moulded 0.75-meter bridge modules 4.

[0077] The bridge modules 4 each have a deck (or deck support) 8 and side parts with a left side-rail 10 and a right side-rail 12. In general the term deck is used to describe the structural lateral element of the bridge. It should be appreciated that this part could form the deck surface (i.e. the surface for walking on in the example of a footbridge) or it could form a structural element that supports infill panels or the like that are the deck surface. The deck 8 and side-rails 10, 12 are adapted so that, when the modules are assembled to form the bridge 2, the decks of the individual bridge modules 4 align to form a continuous deck 9 of the bridge and the side-rails 10, 12 of the individual bridge modules 4 align to respectively form left and right continuous side-rails 11, 13.

[0078] The main load-carrying mechanism of the bridge 2 is the interaction between tension in the tendons 6, compression in compression members formed by stiffened sections at either side of the deck 8, and compression in the left side-rail 11 and the right side-rail 13 of the bridge. The compression members formed by stiffened sections at either side of the deck 8 may be formed by any suitable technique, for example by increasing the thickness of the moulded material, by increasing the amount of fibre reinforcement, or by adjusting the alignment of the fibre reinforcement. The two side rails form the main longitudinal compression member of the bridge. As will be discussed in greater detail later, certain loads during construction may be carried using only the interaction between tension and compression in the deck 8, the left side-rail 11 and the right side-rail 13, i.e. without use of the tendons 6.

[0079] The bridge 2 is post-tensioned meaning that the compression force from the tendons 6 is larger than in a beam bridge where tension is permitted. This means that the dominant critical failure modes are related to buckling. A critical failure mechanism is global buckling. Resistance to this may be improved by introducing curvature to the cross-section of the side-rails 10, 12 and side-panels 14, 16 (see FIGS. 2, 3 and 4).

[0080] The left and right side-rails 10, 12 are respectively connected to the deck 8 via left and right side-panels 14, 16. The side panels 14, 16 carry loads in shear and hence form the main shear element of the bridge. A forward flange 18 and a rearward flange 20 extend around the periphery of the longitudinal ends of the bridge module 4, i.e. extending outward from the side-panels 14, 16 and the deck 8. The flanges 18, 20 of the bridge module 4 each include means 22 for connecting the bridge module 4 to the opposite flanges 18, 20 of adjacent bridge modules 4. These are in the form of shear ball connectors 50, which will be discussed in greater detail later.

[0081] The bridge modules 4 are moulded from a fibre and resin matrix. Suitable fibres include glass fibres and carbon fibres, and suitable resins include epoxy, polyester, vinylester and methacrylate. In one example, Epoxidharz SR1124/SD893x resin, manufactured by Sicomin Epoxy Systems, is laminated with 600 gsm E-glass in approximately 60% ratio. However, other materials will be apparent to those skilled in the art.

[0082] Most preferably, woven or unidirectional cloth reinforcement is used due it its reliable properties. However, this bridge design still works well with very low grade materials. For example, even using polyester resin and chopped strand mat reinforcement, a span of over twenty meters can be achieved.

[0083] In order to provide the required strength and stiffness for the longitudinal compression elements of the bridge 2, in this example formed by the two upper rails 11, 13 and parts of the deck structure 9, then the lay-up of the composite may vary for different parts of the cross-section of the module 4. Thus, as shown by the shaded areas in FIG. 4 there may be upper reinforced regions 70 that provide extra stiffness and strength to form upper longitudinal compression elements of the bridge 2, and lower reinforced regions 72 that provide extra stiffness and strength to form lower longitudinal compression elements of the bridge 2. The reinforced regions may be formed by increased fibres in the composite, by a different lay-up of fibres and so on. The thickness of the material could increase in the same regions, although this is not essential. FIG. 4 also shows variation in the cross-section of the module compared to the module of FIGS. 1 to 3. It will be appreciated that the proposed modular structure can be implemented in a variety of ways, of which these Figures show just two examples.

[0084] The bridge is lightweight and so may be prone to vibration. The deck 8 may optionally use a sandwich panel construction to increase the local stiffness by moulding upper and lower deck panels and installing a core material between the panels after moulding.

[0085] The bridge modules 4 are adapted to receive the tendons 6 by means of through-holes 24 formed in the front and rear flanges 18, 20. In alternative arrangements, the through-holes may pass through the body of the bridge modules 4 such that the tendons 4 are not exposed. The positions of the through-holes 24 correspond to the path of the tendons 6 when tensioned.

[0086] The through-holes 24 do not grip the tendons 6 and serve primarily as guides for the tendons 6 before they are tensioned. However, if the mid-span bridge modules 4 move lateral or vertical, then they will engage the tendons 6 and hence reduce the risk such movement. The through-holes 24 may also facilitate the bridge modules 4 being slid along the tendon 6 during assembly of the bridge, as will be discussed later.

[0087] Advantageously, wheels 26 can be clipped onto each bridge module 4 through these through-holes 24 to facilitate manual transportation around a work site. The use of composite materials means that the mass of each individual bridge module 4 is very low, typically under 200 kg. This allows a worker to manually transport the bridge modules 4 around the work site using the wheels 26 without the need for larger lifting plant, such as cranes.

[0088] The bridge modules 4 can be customised via inserts in the mould, for example for form perforations 28, 30 in the side-panels 14, 16 or the deck 8. An exemplary deck perforation pattern is shown in FIG. 2, and exemplary side-panel perforation patterns are shown in FIGS. 5A to 5C.

[0089] The perforations 28 in the side-panels may further be filled using a material that is visually distinct from the material used to mould the bridge modules 4, such as coloured resins, to create a visible pattern.

[0090] When assembled, the bridge modules 4 are joined using shear ball connectors 50 (see FIG. 8), which together are of sufficient strength to allow the bridge 2 to carry, without the tendons 6, its own self-weight and restricted pedestrian access in the temporary construction and maintenance cases.

[0091] FIG. 8 shows a cross-section through the connector 50 when it is in use to provide a joint between the flanges 52, 54 of two bridge modules 4. Each flange respectively includes a cup-shaped formation 53, 55 at the location of the joint. The shear ball connector 50 comprises a ball-shaped core 56 that is tightly received within a space formed by the cup-shaped formations 53, 55. The core 50 is a substantially spherical ball having an axial through-hole or bore formed therethrough. The connector 50 further comprises two cup-shaped clamping members 58, 60 that respectively engage the outer surfaces of the cup-shaped formations 53, 55 of the flanges 52, 54. A filler layer 68 can be used to account for any manufacturing tolerances and ensure the even spread of forces between the core 50 and the cup-shaped formations 53, 55. The filler layer 68 may be formed from, for example, a resin material poured into the recesses of the cup-shaped formations 53, 55, before they are clamped about the core 50. The resin filler layer 68 will cure and harden so that the resin and core 50 together completely fill the recesses. In an alternative to the use of a core 50 and filler layer 68 the core 50 may be cast in the recesses, for example using a resin, so that the core 50 perfectly fits the recesses.

[0092] A bolt 62 passes through the cup-shaped clamping members 58, 60, the flanges 52, 54 and the core 56, and a nut 64 tightened onto the end of the bolt 62 compresses the two clamping members 58, 60 between the nut 64 and the head 66 of the bolt 62, which in turn compress the cup-shaped formations 53, 55 against the core 56 of the connector 50.

[0093] Although the described embodiment utilises a nut 64 and bolt 62 to apply the compressive force, any suitable means for achieving this effect may be used. For example, two bolts may be used that engage an internal thread formed in the through-hole of the core 56. In another alternative arrangement, the cup-shaped clamping members 58, 60 may be formed integrally with the nut 64 and the head 66 of the bolt 62, respectively. It is also possible to dispense with the bolt and rely solely on the compression from the tendon 6 to hold the flanges 52, 54 against the core 56. In this case the number of parts is reduced but there is no longer any capability to hold a load in tension.

[0094] The shear ball connection 50 allows shear force to be transferred between adjacent bridge modules 4 more effectively because the shear force bear directly on the core 56, which has a larger surface area than the bolt. This prevents localised crushing of the composite, which can be caused by alternative shear connections, such as bolts. The transmission of shear via the core 56 of the shear ball connection 50 is a secondary shear connection, with shear being primarily transmitted between bridge modules 4 via the frictional forces arising due to the compression applied by the bolts 62 and the tendons 6.

[0095] The modular bridge 2 described above may advantageously be installed in a large number of ways, thus allowing for a high degree of flexibility when installing the bridge 2 in areas with restricted access.

[0096] A first method of assembly is shown in FIG. 6, which is suitable for when the bridge 2 can be accessed from below. The bridge modules 4 are sequentially assembled together and the bridge 2 hence forms a beam. This can be with or without the tension cable, since the shear connectors 50 will provide sufficient strength for the bridge 2 to support its own weight. The bridge 2 can then be pulled across the span, supported on the ground beneath. In a variation on this scheme the bridge modules 4 of the bridge 2 need not all be assembled together before the bridge 2 begins to be pulled across the span. Instead the bridge modules 4 can be added to the free end as the bridge 2 pull across. This might be helpful when there is restricted space.

[0097] The tendons 6 may either be fed through the bridge modules 4 as the bridge 2 is being assembled, or they may be fed through the bridge modules 4 once the bridge modules 4 have all be joined together. The tendons 6 are then post-tensioned to the desired tension.

[0098] This assembly technique allows for simple construction without large lifting plant and with a minimal work team. The bridge modules 4 are small enough to be moved via a small van and can be manoeuvred on site by a single worker using the wheels 24 discussed above. A small crane or possibly just a vehicle mounted winch or hand winch should be sufficient to pull the bridge across the span.

[0099] A second method of assembly is shown in FIG. 7. In this technique, all or most of the bridge modules 4 are assembled close to the final position of the bridge. They are then joined together, using intermediate joints (e.g. the shear ball connections 50 described above) to form a unit. The tendons 6 are fastened at one longitudinal end of the span of the bridge, which is opposite to the side on which the bridge modules 4 have been assembled. The tendons 6 are then run across the space to be spanned by the bridge 2 and fed through the bridge modules 4.

[0100] The tendons 6 are then partially tensioned and the joined bridge module unit is slid along the tendons until it reaches its final position. Once in its final position, the bridge is fastened in place and the tendons are post-tensioned to the desired tension.

[0101] As above, the intermediate joints will typically remain in place, but may alternatively be removed or replaced by permanent joints. Furthermore, instead of using the tendons 6, temporary cables may be used to slide the bridge module unit into place, which are then removed and replaced by the tendons 6 to finally post-tension the bridge 2.

[0102] This assembly technique again allows for simple construction without large lifting plant and with a minimal work team. The bridge modules 4 are small enough to be moved via a small van and can be manoeuvred on site by a single worker using the wheels 24 discussed above. They are assembled on the flat and so no lifting equipment is required during assembly.

[0103] This technique is particularly advantageous where access below the bridge is not available, for example because the bridge spans a river, or where it is desirable to minimise the time during which it is accessed, for example where the bridge spans a road or train track. This assembly technique only requires the road of train track to be briefly suspended whilst the bridge module unit is slid into place, which can be done in a matter of hours rather than days.

[0104] Other techniques are possible, for example the tension cables might be fixed in place first, and then individual modules threaded onto the cables from one end in a similar manner to making a string of beads, with the modules then being joined together once threaded onto the cable.

[0105] Further assembly techniques are also envisaged, for example if cranes are available, then the bridge could be assembled nearby and lifted (either using the intermediate joints or post-tensioned) into place using a crane. In a further alternative technique, the bridge could be built in a cantilevered fashion, in which bridge segments are sequentially added from fixed end points at the longitudinal ends of the bridge to meet at about the centre of the span of the bridge.

[0106] Whilst certain exemplary embodiments of the present invention have been described, it will be understood that the present invention is not limited to these embodiments but includes all embodiments falling within the scope of the present invention.

[0107] For example, in certain alternative embodiments, some or all of the mid-span bridge modules 4 may not include through-holes 24, but may instead be adapted to receive the tendons 6 by virtue of their shape, such as by leaving a clear space (e.g. a notch) through which the tendon 6 may pass.

[0108] Furthermore, whilst the shear ball connector 50 has been described for use in combination with composite bridge modules 4, it will be apparent to those skilled in the art that the connector 50 may be used in combination with other composite articles to achieve the same advantages.