EA Box Girder System

Abstract

A precast concrete girder including a substantially planar web extending longitudinally between ends of the girder; a pair of flanges formed integrally with the web, each flange extending laterally from an elongate edge of the web and extending longitudinally between the ends of the girder so as to define a structure engaging surface of the girder; and a plurality of diaphragms formed integrally with the web and the flanges, each diaphragm spanning laterally between a side of the web and one of the flanges, wherein the diaphragms are spaced apart along the girder to thereby support the flanges.

Description

RELATED APPLICATIONS

[0001] There are no previously filed, nor currently any co-pending applications, anywhere in the world.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0002] The present invention relates generally to precast concrete beams and, more particularly, to such precast concrete beams particularly adapted for long span use in the construction of bridges or the like.

2. Description of the Related Art

[0003] Precast concrete beams are currently used in the construction of bridges and other related structures. A range of different beam type is commonly characterized by their cross section shape, i.e., T-beams, I-beams or box beams. Each has benefits depending on the particular structural application.

[0004] Having a characteristic rectangular shaped cross section, box beams are often utilized in bridge construction to providing a vertical web topped with horizontal flanges supporting a road surface deck and distributing loads from the edges of the beam to the vertical web. Prestressed reinforcement members may be provided, particularly at its base. To allow for fewer beams and/or long spans, strength improvements over conventional girder designs are provided, but utilize complex geometries. Greater beam widths result from supporting the flanges cantilevered from the beam centerline, with a thicker base providing improved bending strength.

[0005] Although such improvements allow for longer bridge spans and/or a reduced number of beams to provide a bridge of a particular width, such beams are heavier, complicating installation, and have a more complex geometry that complicates inspection, validation, maintenance, etc.

[0006] Consequently, a need exists for an improved beam design adapted for long span use in the construction of bridges or the like without one or more of these complexities.

SUMMARY OF THE INVENTION

[0007] It is thus an object of the present invention to provide a precast concrete beam particularly adapted for long span use in the construction of bridges or the like.

[0008] It is a feature of the present invention to provide a beam an enlarged bulb formed integrally with the web and opposite upper flanges.

[0009] Briefly described according to the present invention, a box girder design is provided for use in construction of a long span bridge structure. The girder includes a generally vertical web extending longitudinally between an upper horizontal planar support formed and a lower enlarged bulb. The upper horizontal planar support extends cantilevered outward from each side of the web to form a pair of opposing flanges. The enlarged bulb is also formed integrally with the web. The enlarged bulb is shaped having a horizontal lower edge, a pair of vertical opposed side edges, and tapering angularly upward from the side edges to the web. A plurality of diaphragms is formed integrally with the web and spaced apart along the girder and supporting the flanges. Each diaphragm extends from the side of the web and between one of the flanges and the angularly upward taper of the bulb. The diaphragms may be formed in pairs that span between respective sides of the web and respective flanges at the same longitudinal position along the girder. Further, the pairs of diaphragms may be spaced apart by a spacing distance selected so that a load applied to outer portions of the flanges will be transmitted to the web via the diaphragms. A plurality of reinforcing members may extend longitudinally through the bulb, the web, and/or the flanges.

[0010] It is anticipated that the girder would be cast from concrete as a unitary body, with the reinforcing members being prestressed prior to casting.

[0011] An advantage of the present invention is that is allows for longer bridge spans and/or a reduced number of girders to support a particular structure.

[0012] Another advantage of the present invention is that it provides a girder that is lighter for a particular span length than other available configurations.

[0013] Yet another advantage of the present invention is to provide a girder design that allows for a less complicated installation.

[0014] It is other advantages of the present invention to provide a girder geometry facilitates inspection, validation, maintenance and the like.

[0015] Further objects, features, elements and advantages of the invention will become apparent in the course of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings, in which like elements are identified with like symbols, and in which:

[0017] FIG. 1 is a schematic perspective view of a portion of a precast concrete girder according to a preferred embodiment of the present invention;

[0018] FIG. 2 is a schematic end view thereof;

[0019] FIG. 3 is a schematic top view thereof;

[0020] FIG. 4 is a schematic side view of the end portion thereof;

[0021] FIG. 5 is a schematic cross section view thereof taken along section V-V of FIG. 4;

[0022] FIG. 6 is a schematic cross section view thereof taken along section VI-VI of FIG. 4;

[0023] FIG. 7 is a schematic cross section view thereof taken along section VII-VII of FIG. 4; and

[0024] FIG. 8 is a schematic cross section view of an example of a bridge structure formed using the precast concrete girders according to a preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The best mode for carrying out the invention is presented in terms of its preferred embodiment, herein depicted within the Figures. It should be understood that the legal scope of the description is defined by the words of the claims set forth at the end of this patent and that the detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. It should also be understood that, unless a term is expressly defined in this patent there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word "means" and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. .sctn. 112(f).

[0026] The best mode for carrying out the invention is presented in terms of its preferred embodiment, herein depicted within the Figures.

1. Detailed Description of the Figures

[0027] Referring now to the drawings, wherein like reference numerals indicate the same parts throughout the several views, a precast concrete girder, generally noted as 10, is shown according to a preferred embodiment of the present invention for use in long span bridge structures 100 or the like. The girder 10 may include a generally vertical and planar web 12 extending longitudinally between its upper edge 14 and its lower edge 16. A generally horizontal planar support 18 is formed at the upper edge 14 formed integrally with the web. The planar support 18 extends longitudinally outward from the centerline A-A of the web 12 to form a pair of flanges 18a, 18b. The flanges 18a, 18 may extend along the entire length of the girder 10. In some embodiments each flange 18a, 18b may be substantially perpendicularly to the centerline A-A. In other embodiments, the flanges 18a, 18b may be formed extending laterally at an angle relative to the centerline A-A.

[0028] The lower edge 16 may form an enlarged bulb 20 integrally as an extension of the web 12. The bulb 20 may be reinforced and otherwise adapted for improving torsional rigidity and bending strength along the entire cross section of the girder 10. In a preferred embodiment the bulb 20 may form a generally boxlike structure at the lower edge 16 having a base 22, a pair of vertical opposed side edges 24, and tapering angularly upward 26 from the side edges 24. As envisioned, the girder may be cast as a prestress unitary concrete body. It is further envisioned that such casting may be performed remote from the final installation and, as such, the base 22 may provide a support surface for the girder 10 when transported between locations.

[0029] The girder 10 further includes a plurality of diaphragms 30. Each diaphragm 30 may be formed integrally with the web 12 and spaced apart along the girder 10. The diaphragms 30 support the flanges 18a, 18b. Each diaphragm 30 may span laterally between a side of the web 12 and one of the flanges 18a or 18b, respectively.

[0030] Referring best in conjunction with FIG. 7, each diaphragm 30 may span angularly between a flange 18a/18b and an upward taper 26 of the bulb 20. A plurality of such diaphragms 30 may spaced apart along the girder 10. Preferably diaphragms 30 are formed as pairs between respective sides of the web 12 and respective flanges 18a, 18b. More preferably the pairs of diaphragms 30 are positioned at the same longitudinal position along the girder and spaced at a distance sufficient such that a load applied to an outer portion of one of the flanges will be transmitted to the web via one of the diaphragms. It is even more preferable that the spacing 32 of the diaphragms 30 is less than 30 times a flange thickness 34 of the flanges 18a, 18b.

[0031] As shown in conjunction with FIG. 7, each diaphragm 30 spans between a side of the web 14 and one of the flanges 18a, 18b and the angularly upward taper 36 of the bulb 20.

[0032] As shown best in conjunction with FIG. 5, the girder 10 may further comprise one or more end blocks 40. Each end block 40 may be formed at the outermost ends of the girder 10. Each end block 40 may be formed as a vertical extension between opposed side edges between the bulb 20 to the flanges 18a, 18b. It is preferred that each end block 40 may be cast from concrete as part of the unitary body.

[0033] A plurality of reinforcing members 42 may be provided extending longitudinally about the girder 10. The reinforcing members 42 may be provided throughout the various structures of the girder 10, including within the bulb 20, the web 14 or the horizontal planar support 18.

[0034] The configuration of the girder 10 as described may allow for the use of wider girders. The use of wider girders provide improved structural rigidity for use in long spans. This may be provided with the use of wider girders to provide improved performance that may allow for a reduction in the number of girders required for a given span.

[0035] In a preferred embodiment the girder 10 may be cast from concrete as a unitary body. Accordingly, the web 18, diaphragms 30, and flanges 18a, 18b may be integrally formed together. Further, the reinforcing members 42 may be prestressed prior to the casting of the girders 10.

[0036] Referring now to FIG. 3-4, the diaphragms 18a, 18b may be spaced apart by a spacing "L". The spacing "L" may be of a distance sufficient such that a load applied to an outer portion of one of the flanges 18a, 18b will be transmitted to the web 14 via one of the diaphragms 30. In a preferred embodiment the spacing distance "L" may be less than 30 times a flange thickness "T" of the flanges 18a, 18b.

[0037] Within the prestressed cast concrete structure, internal reinforcements 42 may be incorporated. Such reinforcements 42 may be included along the girder 10 at locations that correspond with locations of the diaphragms 30. Reinforcement members 42 may be provided in the form of bars, rods, cables or strands, generally made from a material having a relatively high tensile strength compared to the concrete used to make the precast concrete girder 10. Preferably such material may be steel. More preferably, such material may be formed of carbon fiber composite cable ("CFCC"). Whatever the material, one or more of the reinforcement members 42 may be prestressed when the girder 10 is formed. This may be achieved by positioning the reinforcement members 42 within the casting process and creating a tensile loading before the girder 10 is cast in concrete. This will cause portions of the girder 10 to be in a compressed upon curing, which allows for increased tensile load bearing capacity.

[0038] Finally, as best shown in conjunction with FIG. 1 and FIG. 5, each girder 10 may terminate at one or both ends with an end block 40. It is preferred that each end block 40 may be integrally formed with the web 20, but having an increased thickness compared to the thickness of the web "T". It is more preferable prestressed reinforcement members 42 may traverse through the end blocks 40.

2. Operation of the Preferred Embodiment

[0039] As shown best in conjunction with FIG. 8, in operation the girders 10 allow for use in large span surfaces 100, greater than would otherwise be attainable. The large services span may further be achieved with additional support. The overall strength added by the diaphragms 30 also provide additional support for the horizontal planar support 18.

[0040] Further, it is anticipated that the girders 10 may be precast off-site from a final installation. As such they may be preformed as a prestressed structure.

[0041] It should be apparent to those having ordinary skill in the relevant art, in light of to present teachings, that a number of modifications and variations may exist to the configuration(s) described. It should also be understood that utilizing an effective long span, wide flanged, prestressed girder may be provided for the construction of long span applications such as bridges or the like. By providing such girders 10, bridges or similar structure may be constructed using precast concrete girders in accordance with the present invention that allows for longer bridge spans and/or a reduced number of girders to support a particular structure. Each girder is lighter for a particular span length than other available configurations, and with a design that allows for a less complicated installation. Further, the girder geometry facilitates inspection, validation, maintenance and the like.

[0042] The foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. The Title, Background, Summary, Brief Description of the Drawings and Abstract of the disclosure are hereby incorporated into the disclosure and are provided as illustrative examples of the disclosure, not as restrictive descriptions. It is submitted with the understanding that they will not be used to limit the scope or meaning of the claims. In addition, in the Detailed Description, it can be seen that the description provides illustrative examples and the various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed configuration or operation. The following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

[0043] The claims are not intended to be limited to the aspects described herein, but is to be accorded the full scope consistent with the language claims and to encompass all legal equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of 35 U.S.C. .sctn. 101, 102, or 103, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed. They are not intended to be exhaustive nor to limit the invention to precise forms disclosed and, obviously, many modifications and variations are possible in light of the above teaching. The embodiments are chosen and described in order to best explain principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. It is intended that a scope of the invention be defined broadly by the Drawings and Specification appended hereto and to their equivalents.

Claims

1. A girder for use in construction of a long span bridge structure comprising: a generally vertical web extending longitudinally between a first terminus and a second terminus; a generally horizontal planar support formed integrally with the web at an upper terminus and extending cantilever to form a pair of opposing flanges; an enlarged bulb formed integrally with the web at a lower terminus and opposing the upper terminus, said bulb further having a horizontal lower edge, a pair of vertical opposed side edges, and tapering angularly upward from the side edges to the web; a plurality of diaphragms formed integrally with the web and spaced apart along the girder supporting the flanges, each diaphragm spanning laterally between a side of the web and one of the flanges and the angularly upward taper of the bulb; and a plurality of reinforcing members extending longitudinally between the first terminus and the second terminus through at least one of the group consisting of: the bulb; the web; and the horizontal planar support; wherein the reinforcing members are prestressed and the girder is cast from concrete as a unitary body.

2. The girder of claim 1, further comprising an end block formed at the first terminus and the second terminus, each end block formed as a vertical extension of the vertical opposed side edges between the bulb to the flanges; wherein the end block is cast from concrete as part of the unitary body.

3. The girder of claim 1, wherein said plurality of diaphragms are formed as pairs between respective sides of the web and respective flanges at the same longitudinal position along the girder.

4. The girder of claim 3, wherein said pairs of diaphragms are spaced apart by a spacing distance, and wherein the spacing distance sufficient such that a load applied to an outer portion of one of the flanges will be transmitted to the web via one of the diaphragms.

5. The girder of claim 4, wherein the spacing distance is less than 30 times a flange thickness of the flanges.

6. The girder of claim 1, further comprising laterally extending internal reinforcements at least at longitudinal positions coinciding with the diaphragms.

7. The girder of claim 3, further comprising laterally extending internal reinforcements at least at longitudinal positions coinciding with the diaphragms.

8. The girder of claim 2, wherein said plurality of diaphragms are formed as pairs between respective sides of the web and respective flanges at the same longitudinal position along the girder.

9. The girder of claim 8, wherein said pairs of diaphragms are spaced apart by a spacing distance, and wherein the spacing distance sufficient such that a load applied to an outer portion of one of the flanges will be transmitted to the web via one of the diaphragms.

10. The girder of claim 9, wherein the spacing distance is less than 30 times a flange thickness of the flanges.

11. The girder of claim 8, further comprising laterally extending internal reinforcements at least at longitudinal positions coinciding with the diaphragms.

12. A long span vehicle bridge structure including a plurality of girders according to claim 1.

13. A long span vehicle bridge structure including a plurality of girders according to claim 2.

14. A long span vehicle bridge structure including a plurality of girders according to claim 3.

15. A long span vehicle bridge structure including a plurality of girders according to claim 4.

15. A long span vehicle bridge structure including a plurality of girders according to claim 5.

16. A long span vehicle bridge structure including a plurality of girders according to claim 6.

17. A long span vehicle bridge structure including a plurality of girders according to claim 7.