Bridge construction method and composite girder for use in same

Abstract

A composite girder comprises an elongate member of concrete having a substantially u-shaped or c-shaped cross-section. The girder has a pair of spaced legs connected together by a bridging portion. The legs have substantially flat elongate end faces and exterior reinforcing, such as a steel plate, extends along at least one of said end faces. A method of constructing a bridge using the girder is also provided.

Description

FIELD OF THE INVENTION

[0002] This invention relates to a method of constructing a bridge and a composite girder for use in constructing the bridge.

BACKGROUND OF THE INVENTION

[0003] A composite girder comprising a web of reinforced concrete with steel plates attached to opposite sides of the web to form flanges is described in applicant's earlier U.S. Pat. No. 5,152,112. The patent also describes a method of constructing a bridge using the composite girder.

[0004] The present invention provides a further composite girder and a bridge construction method using such a girder.

SUMMARY OF THE INVENTION

[0005] According to the invention there is provided a composite girder comprising an elongate member of concrete, wherein the concrete member has a substantially U-shaped cross-section including a pair of spaced concrete legs extending transversely of the longitudinal dimension of the concrete member, the spaced legs being connected by a concrete bridging portion formed integrally with the legs, either one of the legs having a pair of opposed elongate sides and an elongate end face extending between the opposed sides and including a reinforcing member mounted on the end face of the leg and extending along the end face of the leg.

[0006] Also according to the invention there is provided a method of constructing a bridge, comprising the steps of laying a plurality of composite girders in parallel relationship across an expanse to form a bridge deck, each girder comprising an elongate member of concrete, wherein the concrete member has a substantially U-shaped cross-section including a pair of spaced concrete legs extending transversely of the longitudinal dimension of the concrete member, the spaced legs being connected by a concrete bridging portion formed integrally with the legs, either one of the legs having a pair of opposed elongate sides and an elongate end face extending between the opposed sides and including a reinforcing member mounted on the end face of the leg and extending along the end face of the leg; and wherein each girder spans the expanse along its longitudinal dimension and said girders are arranged with their legs facing downwardly on support means at the opposite ends of the girder.

[0007] Further according to the invention there is provided a method of constructing a bridge, comprising the step of laying a composite girder across an expanse to form a bridge deck, the girder comprising an elongate member of concrete, wherein the concrete member has a substantially U-shaped cross-section including a pair of spaced concrete legs extending transversely of the longitudinal dimension of the concrete member, the spaced legs being connected by a concrete bridging portion formed integrally with the legs, either one of the legs having a pair of opposed elongate sides and an elongate end face extending between the opposed sides and including a reinforcing member mounted on the end face of the leg and extending along the end face of the leg; and wherein the girder spans the expanse along its longitudinal dimension and the girder is arranged with its legs facing downwardly on support means at the opposite ends of the girder.

[0008] The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a three-dimensional view of a composite girder according to one embodiment of the invention.

[0010] FIG. 2 is a fractional view showing a crosssection along the lines II-II in FIG. 1.

[0011] FIGS. 3 and 4 are fractional views showing cross-sections of two further embodiments of the girder according to the invention.

[0012] FIG. 5 is a cross-sectional view of a casting installation for manufacturing the girder of FIG. 1.

[0013] FIG. 6 is a fractional three-dimensional view showing the manner in which three of the girders of FIG. 1 are arranged in the construction of a bridge.

[0014] FIG. 7 is an end view of a bridge constructed using the girders of FIG. 1.

[0015] FIG. 8 is a side view of the bridge of FIG. 7.

[0016] FIGS. 9 and 10 show the construction of bridges using other embodiments of girders.

[0017] FIG. 11 shows the construction of a bridge using yet another embodiment of a girder.

[0018] FIG. 12 is a side view of another embodiment of a composite girder.

[0019] FIG. 13 is a fractional view showing a cross-section of further embodiment of a girder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] In FIGS. 1 and 2 reference numeral 10 generally indicates a composite girder comprising an elongate member 12 of reinforced concrete and having a generally unshaped or c-shaped cross-section with a pair of spaced legs 14 connected together by a bridging portion 16. An elongate steel plate 18 is attached along the end face of each leg 14 by means of sheer connector studs 20 which are welded to the steel plates 18 as shown at 22. The studs 20 are spaced along the length of each steel plate 18. Although the steel plate 18 is shown to extend along the entire length of the leg 14 in FIG. 1, the steel plate 18 may stop short of the opposite ends of the leg 14 as shown in FIG. 12, i.e. although it strictly does not extend the entire length of the leg 14 it effectively extends along substantially the whole length of the leg 14. The opposite ends of the legs 14 are supported on abutment foundations 116 at the opposite sides of an expanse which is spanned by the bridge.

[0021] Although reference in this example is made to the use of steel plate as reinforcing material, it will be appreciated that any suitable material may be used, e.g. a plastic type material having the same characteristics as steel.

[0022] In the embodiment shown in FIGS. 1 and 2, the steel plates 18 are flush with the sides of the legs 14 as shown. In FIG. 3, showing an alternative embodiment, reference numeral 30 generally indicates a girder in which the steel plates 18 project from one side of the leg 14 to form a flange 32 and in FIG. 4 reference numeral 40 generally indicates a further embodiment in which the steel plates 18 project on both sides of the leg 14 to form two flanges 32 and 34.

[0023] In FIG. 13 reference numeral 100 generally indicates an embodiment in which the steel plate 18 is partially embedded in the concrete.

[0024] Although steel plates 18 are shown to be provided on both legs 14 of the girders 10, 30, 40, it is envisaged that in certain applications a steel plate 18 may be provided on one leg 14 only.

[0025] It will be appreciated further that composite girders of various different sizes may be provided to suit different requirements. For example, the width of the bridging portion 12 and the length of the legs 14, as well as the thickness of the bridging portion 12 and legs 14 and the thickness of the steel plates 18 can be varied to suit the requirements of different bridges for which the girders may be used. Also, the number of rows of the studs 20, the number of studs 20 in a row and the length and type of studs 20 used will depend on a particular application and requirements.

[0026] With reference to FIG. 5, a method of manufacturing the girder 10 of FIG. 1 is shown. A mold 45 in the form of a casing 50 is constructed for forming the legs 14 and the underside of the bridging portion 12. The steel plates 18 with the studs 20 projecting upwardly therefrom are placed along the two channels at the bottom of the mold 45 which define the elongate end faces of the legs 14. Reinforcing rods 52 are then arranged inside the mold 45, as required. A concrete mix is then poured into the mold 45 to fill the mold 45 up a level where the desired thickness of the bridging portion 12 is attained. If desired, chamferring formations may be introduced in the mold 45 to produce chamfers along the opposite elongate edges of the bridging portion 12, as indicated at 54 in FIG. 5.

[0027] Alternatively, the process may be reversed, so that the concrete part is formed in the mold with the legs 14 facing upwards. The steel plate 18 is then set in place into the wet concrete.

[0028] With reference to FIG. 6, the manner in which the girders 10 are arranged during the construction of a bridge is shown. In the particular example, three of the girders 10 are arranged in side-by-side relationship but the number of girders 10 can vary depending on the width of the bridge. For example, for a narrow bridge a single girder 10 may be used.

[0029] With reference to FIGS. 7 and 8, a bridge 60 which has been constructed using the girders 10 is shown. Three girders 10 arranged in side-by-side relationship form the deck of the bridge 60. The girders 10 span the expanse to be bridged lengthwise and are supported at their opposite ends by columns 62 which in the present example are steel pipes. The columns 62 are anchored at their lower ends by means of concrete footings 64 which are cast in situ. At their upper ends the columns 62 are attached to precast concrete beams 66 extending transversely of the girders 10. The girders 10 are arranged on the concrete beams 66 with the metal plates 18 resting on the beams 62.

[0030] The bridge 60 is provided with timber curbs 68, steel railings 70 and guide logs 72, as desired.

[0031] In FIGS. 9 and 10 the construction of bridges is illustrated using girders 80 according to yet another embodiment in which the bridging portions 12 project outwardly from the legs 14 to form flanges 84. The bridge construction of FIG. 9 makes use of two of the girders 80, whereas the bridge construction of FIG. 10 makes use of two of the girders 80 and one of the girders 10. The adjacent girders are connected together by shear connectors, as indicated at 86.

[0032] In FIG. 11 the construction of a bridge is illustrated using girders 90 according to a further embodiment. The girders 90 have a T-shaped cross-section with the metal plate 18 extending along the end face of the leg of the T. The girders 90 are connected together by shear connectors, as indicated at 86. The number of the girders 90 used will depend on the width of the bridge being constructed. The top parts of the girders 90 form the deck of the bridge.

[0033] While the girder according to the invention is described in the present example as being used in the construction of a bridge, it is not limited to such use and it is envisaged that it can be used in the construction of other structures.

[0034] The girder according to the invention can be manufactured in one piece to reach a required span by providing adequate reinforcing in the concrete or, as an alternative, or, in addition, pretensioning or posttensioning the concrete to meet the load bearing demands to which the girder may be subjected.

[0035] Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.

Claims

1. A composite girder comprising an elongate member of concrete, wherein the concrete member has a substantially U-shaped cross-section including a pair of spaced concrete legs extending transversely of the longitudinal dimension of the concrete member, the spaced legs being connected by a concrete bridging portion formed integrally with the legs, either one of the legs having a pair of opposed elongate sides and an elongate end face extending between the opposed sides and including a reinforcing member mounted on the end face of the leg and extending along the end face of the leg.

2. The girder according to claim 1, wherein the reinforcing member is in the form of a elongate plate.

3. The girder according to claim 2, wherein the plate is flush with the elongate sides of the leg.

4. The girder according to claim 2, wherein the plate forms a flange projecting from at least one elongate side of the leg.

5. The girder according to claim 2, wherein the plate forms flanges extending from both elongate sides of the leg.

6. The girder according to claim 2, wherein the plate is attached to the end face of the leg by means of a plurality of stud connectors spaced along the end face.

7. The girder according to claim 2, wherein the plate is at least partially embedded in the end face.

8. The girder according to claim 2, wherein the plate is a steel plate.

9. A method of constructing a bridge, comprising the steps of laying a plurality of composite girders in parallel relationship across an expanse to form a bridge deck, each girder comprising an elongate member of concrete, wherein the concrete member has a substantially U-shaped cross-section including a pair of spaced concrete legs extending transversely of the longitudinal dimension of the concrete member, the spaced legs being connected by a concrete bridging portion formed integrally with the legs, either one of the legs having a pair of opposed elongate sides and an elongate end face extending between the opposed sides and including a reinforcing member mounted on the end face of the leg and extending along the end face of the leg; and wherein each girder spans the expanse along its longitudinal dimension and said girders are arranged with their legs facing downwardly on support means at the opposite ends of the girder.

10. The method according to claim 9, wherein the reinforcing member is in the form of an elongate plate.

11. The method according to claim 10, wherein the plate is a steel plate.

12. The method according to claim 9, wherein the legs of adjacent girders are in side-by-side abutment.

13. A method of constructing a bridge, comprising the step of laying a composite girder across an expanse to form a bridge deck, the girder comprising an elongate member of concrete, wherein the concrete member has a substantially U-shaped cross-section including a pair of spaced concrete legs extending transversely of the longitudinal dimension of the concrete member, the spaced legs being connected by a concrete bridging portion formed integrally with the legs, either one of the legs having a pair of opposed elongate sides and an elongate end face extending between the opposed sides and including a reinforcing member mounted on the end face of the leg and extending along the end face of the leg; and wherein the girder spans the expanse along its longitudinal dimension and the girder is arranged with its legs facing downwardly on support means at the opposite ends of the girder.

14. The method according to claim 13, wherein the reinforcing member is in the form of a steel plate.