REINFORCING BAR SPLICE WITH THREADED COLLARS
A reinforcing bar splice secures together reinforcing bar ends by utilizing, at both ends, both tapered-thread coupling and coupling involving a filler, such as a grout or an epoxy. The splice may include a central tapered-thread central sleeve or coupler, and a pair of collars that are screwed onto externally-threaded ends of the central sleeve. The central sleeve has a channel therethrough with tapered internal threads at both ends, and a center internal relief. The internal relief is an increased radius center portion that ensures full thread contact between the tapered internal threads and external threaded sections of the rebar ends. The sleeve has externally-threaded ends that are engaged by internally-threaded ends of a pair of collars. Distal to their internally-threaded ends, the collars have filler-material-receiving channels. The channels include plural sloped surfaces for aiding in securing filler material between the collars and the rebar ends.
This application claims priority under 35 USC 119 to U.S. Provisional Application No. 60/758,687, filed Jan. 13, 2006.
BACKGROUND OF THE INVENTION1. Technical Field of the Invention
This invention relates generally to reinforcing bar splices.
2. Description of the Related Art
High tensile strength splices for reinforcing bar used in concrete construction have been widely employed. One type using a sleeve with internal deformations employs as a locking element filler metal formed from an exothermic reaction, such molten metal entering the sleeve through a tap hole. When the metal solidifies it forms a lock between the deformation on the interior of the sleeve, and the typical deformations found on the exterior of the reinforcing bar. These types of splices are sold by ERICO Inc. of Solon, Ohio, under the trademark CADWELD®. Examples of such splices may be seen in prior U.S. Pat. Nos. 3,234,603 and 3,255,498, to Leuthy et al.
Another type of reinforcing bar splice that is widely employed is a threaded splice connection. A sleeve with internal threads is threaded into a bar with external threads. One such system which is widely employed and frequently specified is a taper thread system such as that made and sold by ERICO Inc. of Solon, Ohio under the trademark LENTON®.
Another type of splice is a grout splice system, such as that shown in Yee, U.S. Pat. Nos. 3,540,763 and 4,672,212. These patents use a sleeve with internal deformations and a volume stable grout to form a locking element within the sleeve locking on the internal deformations of the bar, much like the metal of the earlier Leuthy patents.
All of these methods have their advantages and disadvantages, and none is ideal for all situations. Therefore there is room for improvement in the area of reinforcing bar splices.
SUMMARY OF THE INVENTIONAccording to an aspect of the invention, a reinforcing bar splice includes: an internally threaded sleeve, and a pair of internally threaded collars that engage externally threaded ends of the sleeve. The collars have openings that are configured for receiving reinforcing bar ends, and securing the bar ends therewithin using an epoxy or grout.
According to another aspect of the invention, a reinforcing bar splice includes an internally threaded section for threadedly engaging tapered thread ends of reinforcing bars, and wider sections at distal ends of the splice, for engaging the reinforcing bars with a grout or epoxy. The wider sections may have ramped or sloped surfaces for improving the holding of the grout or epoxy.
According to yet another aspect of the invention, an internally tapered threaded reinforcing bar splice has a central relief therein. The central relief relieves thread stress concentrations, which may help retard fatigue crack initiation.
According to still another aspect of the invention, a reinforcing bar splice engages each of a pair of reinforcing bar ends with both tapered threads and an epoxy or grout.
According to a further aspect of the invention, a tapered thread reinforcing bar splice achieves improved fatigue performance by transferring some of the load from a tapered thread portion of the splice to an epoxy- or grout-filled portion of the splice.
According to another aspect of the invention, a reinforcing bar splice includes: a sleeve having sleeve internal tapered threads at opposite sleeve ends; and a pair of collars mechanically coupled to the ends, and extending axially beyond the sleeve ends.
According to yet another aspect of the invention, a method of coupling reinforcing bar ends, includes the steps of: securing in external tapered thread portions of the reinforcing bar ends in opposite internal tapered thread ends of a sleeve; and placing filler material between the reinforcing bar ends and collars that are mechanically coupled to the sleeve. The filler material may include a grout and/or an epoxy.
To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
In the annexed drawings, which are not necessarily to scale:
A reinforcing bar splice secures together reinforcing bar ends by utilizing, at both ends, both tapered-thread coupling and coupling involving a filler, such as a grout or an epoxy. The splice may include a central tapered-thread central sleeve or coupler, and a pair of collars that are screwed onto externally-threaded ends of the central sleeve. The central sleeve has a channel therethrough with tapered internal threads at both ends, and a center internal relief. The internal relief is an increased radius center portion that ensures full thread contact between the tapered internal threads and external threaded sections of the rebar ends. The sleeve has externally-threaded ends that are engaged by internally-threaded ends of a pair of collars. Distal to their internally-threaded ends, the collars have filler-material-receiving channels. The channels include plural sloped surfaces for aiding in securing filler material between the collars and the rebar ends. The sloped surfaces also transfer some of the load from the rebar ends to the collars, thus reducing the amount of load on the tapered coupling between the bar ends and the central sleeve. The filler material may be an epoxy or grout, or may alternatively be another suitable material, such as a reactive metal-producing material.
The sleeve 16 includes a central through-hole 24. The ends 26 and 28 of the sleeve 16 are internally threaded along the hole 24 at tapered thread portions 30 and 31 of the hole 24, with respective tapered threads 32 and 34. The tapered threads 32 and 34 are configured to engage corresponding externally-threaded tapered portions 36 and 38 of the rebar ends 12 and 14. The rebar ends 12 and 14 are coupled to the central sleeve 16 by rotating the ends 12 and 14, and/or the sleeve 16, to threadedly engage the rebar end threaded portions 36 and 38 with the tapered threads 32 and 34 of the sleeve. In this manner the sleeve 16 becomes a tensile and compressive extension of the reinforcing bar ends 12 and 14. Further details regarding threaded rebar coupling may be found in U.S. Pat. No. 5,366,672, the description and drawings of which are herein incorporated by reference.
The sleeve 16 has a center internal relief 40 in a center portion of the hole 24. The internal relief 40 is an increased radius center portion that ensures full thread contact between the tapered internal threads 32 and 34 and the external threaded sections or portions 36 and 38 of the rebar ends 12 and 14. The internal relief 40 ensures that the rebar ends 12 and 14 can be inserted in the sleeve through-hole 24 past the last engaged thread of the internally-threaded portions 32 and 34. The internal relief 40 also relieves thread stress concentrations, and thus may help eliminate or retard fatigue crack initiation.
The sleeve 16 has external threads 42 and 44 at the sleeve ends 26 and 28. The external threads 42 and 44 engage respective first (proximal) ends 48 and 50 of the collars 18 and 20. The collar first ends 48 and 50 have internal threads 52 and 54 configured to engage the sleeve external threads 42 and 44, to couple the collars 18 and 20 to the sleeve ends 26 and 28. The collars 18 and 20 are coupled to the sleeve ends 26 and 28 by suitable aligning and rotating the collars 18 and 20 and/or the sleeve 16 to threadedly engage them.
The collars 18 and 20 have respective through-holes 52 and 54 for allowing the rebar ends 12 and 14 to pass therethrough for threaded coupling to the central sleeve 16. As described in the previous paragraph, at the first collar ends 48 and 50 the through-holes 52 and 54 are internally threaded to engage the sleeve ends 26 and 28. At second (distal) collar ends 58 and 60 the through-holes 52 and 54 have respective filler-material-receiving channels 62 and 64. The channels 62 and 64 have a diameter that is greater than that of the rebar ends 12 and 14. The diameter of the channels 62 and 64 is also greater than a maximum diameter of the sleeve through-hole 24 at the internal threads 32 and 34 (at the mouths of the through-hole 24). The channels 62 and 64 are sized to allow entry of filler material 66 after the rebar ends 12 and 14 have been inserted through the collars 18 and 20, and threadedly engaged with the central sleeve 16. Thus spaces 68 and 70 within the collars 18 and 20, around the rebar ends 12 and 14, may be filled with the filler material 66, to aid in securing the rebar ends 12 and 14.
The channels 62 and 64 each include plural sloped surfaces for aiding in securing filler material between the collars and the rebar ends. In the illustrated embodiment each of the channels 62 and 64 has four sloped surfaces, although it will be appreciated that a greater or lesser number of sloped surfaces may be employed. The channel 62 has sloped surfaces 71, 72, 73, and 74, and the channel 64 has sloped surfaces 75, 76, 77, and 78. The sloped surfaces 71-78 are angled so that they are directed radially inward, such that they are closer to the rebar ends 12 and 14 where they are closer to the distal collar ends 58 and 60, away from the sleeve 16. The sloped surfaces 71-78 transfer some of the load from the rebar ends 12 and 14 to the collars 18 and 20, thus reducing the amount of load on the tapered thread coupling between the bar ends 12 and 14, and the central sleeve 16. Because of the sloped surfaces 71-78, tensile stresses on the rebar ends 12 and 14, are in part converted into compression stresses in the filler material 66. These compression stresses in the filler material 66 are converted, via the sloped surfaces 71-78, into hoop stresses in the collars 18 and 20. Since filler materials such as grout or epoxy are stronger in compression than in tension, it will be appreciated that it is advantageous to transform tension stresses in the rebar end 12 and 14, into compression stresses in the filler material 66. Further, the collars 18 and 20, being made of metal, resist hoop stresses very well, and therefore it is advantageous to dissipate compression stresses in the filler material 66 as hoop stresses in the collars 18 and 20.
The sleeve 16 and the collars 18 and 20 may be made of a suitable material, such as steel. The filler material for the collars 18 and 20 may be an epoxy or grout, or may alternatively be another suitable material, such as a reactive metal-producing material, such as used in ERICO systems sold under the trademark CADWELD®.
In assembly, the collars 18 and 20 are first threadedly engaged on the external threads 42 and 44 of the sleeve ends 26 and 28. Then the rebar ends 12 and 14 are threadedly engaged with the internal tapered threads 32 and 34. (The two proceeding steps may be reversed in order, if desired.) Finally the spaces 68 and 70 are filled with the filler material 66. A grout or epoxy filler material is allowed to cure, to complete the splice 10.
The splice 10 advantageously disperses or spreads stress out over a larger area of the rebar ends 12 and 14. Since some of the stress on the rebar ends 12 and 14 is transferred to the collars 18 and 20, rather than the central sleeve 16, the splice 10 is better able to withstand stress, and may have better fatigue performance.
The splice 10 has better performance than conventional tapered thread splices with regard to two fatigue failure modes. One mode where conventional tapered thread splices fail is due to failure of the rebar at the middle of the tapered thread sleeve. The presence of the internal relief 40 at the middle of the sleeve 16 helps prevent this type of failure.
Another type of failure in conventional tapered thread splices is failure of the rebar at the mouth of the tapered thread sleeve, where the rebar ends exit the sleeve. The presence of the filler material 66 at this location in the splice 10 helps reduce stresses, aiding in avoiding this sort of failure as well.
It will be appreciated that the splice 10 shown in the figures and described above is but one embodiment of the invention. Many variations are possible, including different ways of physically coupling a sleeve and collars, and different ways of configuring the sleeve and/or the collars. Some of the features described herein may be omitted, if desired, or may be combined with other features.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.
Claims
1. A reinforcing bar splice comprising:
- a sleeve having sleeve internal tapered threads at opposite sleeve ends; and
- a pair of collars mechanically coupled to the ends, and extending axially beyond the sleeve ends.
2. The splice of claim 1, wherein the collars have collar internal threads at distal collar ends that threadedly engage sleeve external threads at the sleeve ends.
3. The splice of claim 2, wherein the collars have respective channels at proximal ends that have diameters greater than maximum diameters of tapered-thread portions of the sleeve.
4. The splice of claim 3, further comprising filler material in the channels.
5. The splice of claim 4, wherein the filler material includes an epoxy.
6. The splice of claim 4, wherein the filler material includes a grout.
7. The splice of claim 3, wherein each of the channels has plural sloped inner surfaces, wherein the sloped inner surfaces have a smaller diameter closer to the distal end of the collar.
8. The splice of claim 1,
- wherein the sleeve has a through-hole; and
- wherein the sleeve internal tapered threads are at tapered-thread portions at opposite ends of the through-hole.
9. The splice of claim 1, wherein the sleeve has an internal relief at a central portion of the through-hole.
10. The splice of claim 1,
- in combination with a pair of rebar ends;
- wherein the rebar ends have external tapered thread portions threadedly engaged with the internal tapered threads of the sleeve.
11. The combination of claim 10, further comprising filler material in spaces between the collars and respective of the rebar ends.
12. The combination of claim 11, wherein the filler material includes one or more of an epoxy and a grout.
13. The combination of claim 12, wherein the collars have collar internal threads at distal collar ends that threadedly engage sleeve external threads at the sleeve ends.
14. The combination of claim 13, wherein each of the channels has plural sloped inner surfaces, wherein the sloped inner surfaces have a smaller diameter closer to the distal end of the collar.
15. The combination of claim 14, wherein tensile stresses on the rebar ends is converted at least in part to compressive stresses in the filler material, which in turn is converted at least in part to hoop stresses in the collars.
16. The splice of claim 15,
- wherein the sleeve has a through-hole; and
- wherein the sleeve internal tapered threads are at tapered-thread portions at opposite ends of the through-hole.
17. The splice of claim 16, wherein the sleeve has an internal relief at a central portion of the through-hole.
18. A method of coupling reinforcing bar ends, the method comprising:
- securing external tapered thread portions of the reinforcing bar ends in opposite internal tapered thread ends of a sleeve; and
- placing filler material between the reinforcing bar ends and collars that are mechanically coupled to the sleeve.
19. The method of claim 18, wherein the filler material includes at least one of an epoxy and a grout.
Type: Application
Filed: Jan 10, 2007
Publication Date: Aug 2, 2007
Inventors: Paul B. Allen (Medina, OH), Louis J. Colarusso (Macedonia, OH), Dieter Russwurm (Langenargen), Ward M. Judson (Hudson, OH)
Application Number: 11/621,596
International Classification: E04C 3/30 (20060101);
