EA I-U-T Girder System

Abstract

A precast concrete beam including a substantially planar web extending longitudinally between ends of the beam; 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 beam so as to define a structure engaging surface of the beam; 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 beam to thereby support the flanges.

Claims

1. A beam 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 beam 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 beam is cast from concrete as a unitary body.

2. The beam 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 beam 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 beam.

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

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

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

8. The beam 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 beam.

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

11. The beam 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 beams according to claim 1.

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

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

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

16. A long span vehicle bridge structure including a plurality of beams according to claim 5.

17. A long span vehicle bridge structure including a plurality of beams according to claim 6.

18. A long span vehicle bridge structure including a plurality of beams according to claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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:

[0020] FIG. 1 is a schematic perspective view of a portion of a precast concrete beam according to a preferred embodiment of the present invention;

[0021] FIG. 2 is a schematic end view thereof;

[0022] FIG. 3 is a schematic top view thereof;

[0023] FIG. 4 is a schematic side view of the end portion thereof;

[0024] FIG. 5 is a schematic cross section view thereof taken along section VA/of FIG. 4;

[0025] FIG. 6 is a schematic cross section view thereof taken along section VI-VI of FIG. 4;

[0026] FIG. 7 is a schematic cross section view thereof taken along section VII-VII of FIG. 4;

[0027] FIG. 8 is a schematic cross section view of an example of a bridge structure formed using the precast concrete beams according to a preferred embodiment of the present invention;

[0028] FIG. 9 is a schematic cross sectional view of a beam bridge configuration according to an alternate embodiment of the present invention;

[0029] FIG. 10 is a cross sectional view taken along line X-X of FIG. 9 showing the individual precast U-beam configuration;

[0030] FIG. 11 is an exemplary truss panel for use therewith;

[0031] FIG. 12 is a cross sectional view of a composite deck panel taken along line XII-XII of FIG. 11;

[0032] FIG. 13 is a cross sectional view of the U-beam design of FIG. 9 shown with steel reinforcement tubes incorporated therein;

[0033] FIG. 14 is an exemplary elevational view of a truss system incorporating the U-beam designs of FIG. 13;

[0034] FIG. 15 is an exemplary cross sectional view of a decked I-beam (“DIB”) bridge design shown according to the present invention for a design of a 350 foot span;

[0035] FIG. 16 is a schematic cross section view taken along line XVI-XVI of the DIB bridge deck section of FIG. 15;

[0036] FIG. 17 is a cross section of the transfer ribs of the design of FIG. 16;

[0037] FIG. 18 is an exemplary configuration of a midspan of the DIB design showing the truss design and configuration;

[0038] FIG. 19 is a bursting reinforcement detail of the DIB design; and

[0039] FIG. 20 is an exemplary cross sectional view of a decked I-beam (“DIB”) bridge design shown according to the present invention for a design of a 250 foot span.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] 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. § 112(f).

[0041] 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

[0042] Referring now to the drawings, wherein like reference numerals indicate the same parts throughout the several views, a precast concrete beam, 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 beam 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 beam 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.

[0043] 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 beam 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 beam 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 beam 10 when transported between locations.

[0044] The beam 10 further includes a plurality of diaphragms 30. Each diaphragm 30 may be formed integrally with the web 12 and spaced apart along the beam 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.

[0045] 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 beam 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 beam 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.

[0046] 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.

[0047] As shown best in conjunction with FIG. 5, the beam 10 may further comprise one or more end blocks 40. Each end block 40 may be formed at the outermost ends of the beam 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.

[0048] A plurality of reinforcing members 42 may be provided extending longitudinally about the beam 10. The reinforcing members 42 may be provided throughout the various structures of the beam 10, including within the bulb 20, the web 14 or the horizontal planar support 18.

[0049] The configuration of the beam 10 as described may allow for the use of wider beams. The use of wider beams provide improved structural rigidity for use in long spans. This may be provided with the use of wider beams to provide improved performance that may allow for a reduction in the number of beams required for a given span.

[0050] In a preferred embodiment the beam 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 beams 10.

[0051] 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.

[0052] Within the prestressed cast concrete structure, internal reinforcements 42 may be incorporated. Such reinforcements 42 may be included along the beam 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 beam 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 beam 10 is formed. This may be achieved by positioning the reinforcement members 42 within the casting process and creating a tensile loading before the beam 10 is cast in concrete. This will cause portions of the beam 10 to be in a compressed upon curing, which allows for increased tensile load bearing capacity.

[0053] Finally, as best shown in conjunction with FIG. 1 and FIG. 5, each beam 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

[0054] As shown best in conjunction with FIG. 8, in operation the beams 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.

[0055] Further, it is anticipated that the beams 10 may be precast off-site from a final installation. As such they may be preformed as a prestressed structure.

[0056] 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 beams 10, bridges or similar structure may be constructed using precast concrete beams in accordance with the present invention that allows for longer bridge spans and/or a reduced number of beams to support a particular structure. Each beam is lighter for a particular span length than other available configurations, and with a design that allows for a less complicated installation. Further, the beam geometry facilitates inspection, validation, maintenance and the like.

[0057] As shown in conjunction with FIG. 9 through FIG. 14, an improved precast concrete beam is shown according to an alternate embodiment of the present invention showing a U-beam configuration. Preliminary analysis shows that section configuration as shown is adequate to resist the bending moment demand using approximately (150) 0.7-in, strands in each member. A close-up of the cross-section of the beam is shown in FIG. 10. It was estimated that no. 4 grade 60 hooked bars may be placed in each top bulb at 12-inch spacing to resist the interface shear demand. Such a spacing fits inside the voids of the precast truss panel, allowing for composite connection between the beams and the top slab. Such a deck slab may consists of a 1.5-inch thick precast UHPC layer with two welded wire steel trusses and a 6.5-in. thick CIP conventional concrete (CC) layer that placed at time of construction as shown in FIG. 11.

[0058] The cross-section of the composite deck panel is shown in FIG. 12. To further optimize the shape, a middle third of the beam has webs replaced with hollow structural sections (“HSS”) steel tubes to reduce the weight of the precast beam. The cross-section of the tub beam, including these steel tubes, are shown in FIG. 13. The steel tubes are placed as a truss system along the length of the beams, an elevation view is shown in FIG. 14. These beams are also subjected to very high prestressing forces at release. To prevent cracking of the member at time of release, steel will need to be added within a distance of h/4. However, the contribution due to the fibers can be accounted for. For the tub beams, approximately twelve no. 7 grade 60 bars are needed at each end, with six bars being in one web and six bars being in the other. The fibers are assumed to be able to carry the rest of the stress. Such a configuration may allow for larger girder systems to be used for a bridge deck, while requiring a fewer number of girders overall. While the larger girders themselves may be larger, heavier and potentially more expensive than conventional girders, the use and installation of a fewer number of girders allows for overall savings in weight, cost and installation time.

[0059] Referring to FIG. 16 through FIG. 19, a Decked I-Beam System Design utilizing the present teachings is shown in an exemplary span of 350 feet. Similar to the “U” tub beam, the 350 foot span decked I-beam (DIB) bridge system uses four DIBs that are 12 feet in depth with a beam spacing of 12-ft 8-in. Rather than using a deck slab or the shown composite truss panel, the deck is integrated into the beam, allowing for simple and quick production. The deck is ribbed to save on material costs, as the entire depth is not needed to obtain sufficient strength and resist transverse bending. Bars can be placed transversely in these ribs to provide enough bending strength as well as for a joint connection. The cross-section of the bridge is shown in FIG. 15. Note that the transverse bars are not shown in this section for clarity.

[0060] Preliminary analysis shows that the provided section is adequate to resist the bending moment demand using approximately (90) 0.7-in, strands in each member. (24) holes, approximately 6/8-in, in diameter are also provided in the top flange to allow for future post-tensioning of 0.5-in, strands. This allows for camber to be adjusted on site.

[0061] A close-up of the cross-section of the beam is shown in FIG. 16. Note the big gap between strands in the center of the beam. This allows for the UHPC mix to be able to flow uninterrupted to the bottom, helping prevent any fiber bridging between center strands. Tentatively, no. 6 grade 60 bars are placed in the top and bottom of each rib to allow for sufficient connection of the beams, as well as to resist any positive and negative bending of the integrated deck.

[0062] The cross-section of the ribs is shown in FIG. 17. To further optimize the shape, the beam would be formed as a truss beam for the middle 60 percent of the length. This is shown in FIG. 18. Triangular shaped voids would be formed using expanded polystyrene (EPS) or similar. This substantially reduces both the weight of the member and the amount of material needed. Previous research and testing of UHPC members did not show any issues with including these large opening, so it is assumed that this detail would not create issues with stress and strength demands. These beams are subjected to very high prestressing forces at release. To prevent cracking of the member at time of release, steel will need to be added within a distance of h/4. However, the contribution due to the fibers can be accounted for. For the decked !-beam, approximately (6) no. 6 grade 60 bars are needed at each end. The fibers are assumed to be able to carry the rest of the stress.

[0063] Placement of the bursting reinforcement is shown in FIG. 19. It should be noted that according to existing codes and design guides of the Precast/Prestressed Concrete Institute, the longest pre-stressed precast I-beam known is around 220 ft. Utilizing the teachings of the present invention, possibilities now exist for Long Span Bridges utilizing UHPC or similar concrete mix designs in excess of 220 feet. For the 250′ span I-beam, a member has similar framing to that of the 350 ft span design, but the beams are 9 ft deep and approximately 9 ft wide. The cross-section of this beam is shown in FIG. 22. The design of this beam shows that (54) 0.7-in, strands are adequate for this span. Additionally, (26) holes are placed in the top of the member to allow for in-field post-tensioning of 0.5-in. strands so that the camber can be adjusted as needed.

[0064] Note that the main difference in the 350 foot span beam and the 250 foot span beam is the joint shape. The joint shape in the 350 ft span shows a joint that is easy to form for field casting where backer rod can be placed in the bottom flanges, while this beam uses a more standard detail. This beam also uses the same ribbed section as shown previously and shown here in FIG. 22 For this section, it is assumed that a no. 6 grade 60 bar will need to be placed in the bottom of each rib, similar to the other DIB (350′) CIP Design, but without the top bar. This means that the fibers are relied on to resist the negative bending moment. (6) no. 6 bars would also need to be placed in each end to resist bursting stresses.

[0065] 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.

[0066] 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. § 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.