Patent Application
20130028658
1. Field of the Invention
The present invention generally relates to a splice sleeve tube device for joining the ends of at least two reinforcing bars utilized in various types of structures in which steel reinforcing bars are utilized, and it is desired to interconnect the overlapping end portions of such reinforcing bars. The splice sleeve tube device has an elliptical cross section or a curved cross section composed of curvatures of varying radii, referred to herein as a compound curve cross section, to receive and accommodate the end portions of the reinforcing bars in an overlapping relationship, with the splice sleeve being filled with hardenable material to resist axial tension or compression exerted on the reinforcing bars.
2. Description of the Related Art
The tube devices of the present invention serve the same purpose as my previous splice sleeves for reinforcing bars or rebar that are well known as exemplified in my prior U.S. Pat. No. 3,540,763 issued Nov. 17, 1970, for SPLICE SLEEVE FOR REINFORCING BARS. In this patent, the reinforcing bars connected by the sleeve and cementitious material are in axial alignment. Splice sleeves for connecting overlapping reinforcing bar end portions are also known, as exemplified in my prior U.S. Pat. No. 4,692,052 issued Sep. 8, 1987, for SPLICE SLEEVE FOR OVERLAPPING REINFORCING BARS. In this patent, the sleeve has a cylindrical cross section configuration.
The present invention generally relates to a splice sleeve for joining at least two reinforcing bars or rebars used in various types of structures in which steel reinforcing bars are utilized and it is desired to connect the overlapping end portions of the reinforcing bars. As used herein, the terms “reinforcing bars” and “rebars” are used interchangeably and the term “compound curve” refers to curvatures of varying radii for the cross section of the splice sleeve tube device of the present invention.
The splice sleeve of the present invention has an elliptical cross section or one constructed in the form of compound curves and is configured to receive and accommodate the overlapped ends of the reinforcing bars along the radial axis having the greatest dimension. When the rebar ends are in place in the splice sleeve, the sleeve is then filled with hardenable material to resist axial tension or compression exerted on the reinforcing bars. The action of the sleeve is to hold the hardenable material in tight confinement against the surfaces of the overlapping reinforcing bar ends so that the surface deformation ridges of these bars will provide a tight gripping action with the confined hardenable material.
The hardenable material may contain an expansion agent which results in limited expansion of the grout mass that is firmly confined in the interior area of the tube sleeve. The inclusion of an expansion agent can induce tremendous internal pressures on the lapped ends of the rebars which greatly increases the bonding and strength of the connection.
The splice sleeve of the present invention is preferably provided with an inwardly directed lip at one or both ends. The lip reduces the inner diameter of the sleeve at the ends to provide added restraint against longitudinal shifting of the internal grout mass and therefore maximizing the confinement of the overlapping ends of the connected rebars. Another purpose of these lips is to serve as a guide to position the rebars to allow a gap of at least 3 mm between the outer rebar surface and the interior surface of the splice sleeve tube thus allowing the liquid hardenable grout to fill the gap and provide the necessary peripheral grout mass for confinement and frictional resistance of the rebars.
Accordingly, an object of the present invention is to provide a splice sleeve for interconnecting reinforcing bars in the form of a rigid sleeve having an elliptical or compound curve cross section in which the overlapping ends of the reinforcing bars are positioned in the sleeve. The space between the reinforcing bar ends and between the bars and the sleeve is filled with hardenable cementitious material such as grouting or the like so that the sleeve will restrain any radial displacement of the cementitious material thereby developing a confinement of the cementitious material and preventing it from outward movement thereby resulting in substantial “lock” between the surface deformation ridges of the rebars to provide significant resistance to axial tension and/or compression failure or displacement of the overlapped reinforcing bar ends.
Another object of the present invention is to provide a splice sleeve with an elliptical or compound curve cross section to allow sufficient tolerance and accommodation for overlapping reinforcing bars as set forth in the preceding object in which the elliptical or compound curve cross section splice sleeve has a first radial axis and a second radial axis that are generally perpendicular to each other with a first inner diameter of the elliptical or compound curve cross section sleeve as measured along the first radial axis (“the major axis”) being greater than a second inner diameter of the sleeve as measured along the second radial axis (“the minor axis”), perpendicular to the first radial axis, with the overlapping rebar ends being spaced from one another along the first radial, or major, axis.
A further object of the present invention is to provide a splice sleeve with an elliptical or compound curve cross section for overlapping reinforcing bars as set forth in the preceding objects in which one or both ends of the sleeve include an inwardly directed lip that provides added restraint against shifting of the internal grout mass and increases the splicing capacity of the overlapping sleeve arrangement as compared with cylindrical sleeve configurations. The inwardly directed lip at the ends of the sleeve also serves to position the rebar in a way to form a minimum gap of 3 mm between the rebar and the interior surface of the sleeve to ensure that a minimum thickness of the internal grout mass can be effectively formed completely around the perimeter of the rebar ends for the development of maximum bonding and shear resistance when restrained by the inwardly directed lip at each end of the sleeve.
A still further object of the present invention is to provide an elliptical or compound curve cross section splice sleeve for overlapping reinforcing bars which is simple in construction, easy to assemble and effective for securely restraining the overlapped ends of the reinforcing bars in connected relation in order to resist axial tension and/or compression exerted on the reinforcing bars.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.
In describing preferred embodiments of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
Referring now specifically to the drawings and
As illustrated in
As shown in
The wall thickness of the sleeves is generally constant at about 4.5 mm as this is generally the thinnest casting wall thickness for practical production casting that will provide adequate stiffness for restraint and confinement of the grout mass. The wall thickness could vary, however, depending upon the specific application and/or developments in the art and the present invention is intended to include such variations.
When in a horizontal orientation as shown in
The elliptical or compound curve cross section shape of the splice sleeve according to the present invention has been shown to better accommodate the overlapped steel bars and increase ease in placement, while also providing greater coverage of concrete over the interior of the elliptical sleeve. The increased ease of placement during installation arises from having more internal tolerance to fit rebars, which naturally will allow thicker grout coverage within the sleeve. Preferably, the overlapping ends of the bars are positioned side by side within the sleeve along the major axis and spaced to be on either side of the longitudinal center axis of the sleeve. The ends can overlap to varying degrees, such as over 50% of the sleeve length, over 60% of the sleeve length, over 70% of the sleeve length, etc., but it is preferred that the rebar ends overlap along the entire length of the sleeve, i.e., the overlap length is made equal to the length of the sleeve for 100% overlap, as shown in
According to a preferred embodiment, each bar is spaced from the longitudinal center axis closely equidistant (3 mm minimum) on each side of the center axis and a minimum of 3 mm from the inner side walls of the sleeve. However, other spacings and placements may be used while still obtaining acceptable improvements in tension and compression resistance from the elliptical or compound curve cross section sleeve.
As shown in
When subjected to actual load testing on three sizes of reinforcing steel bars fixed within the sleeve connector by hardened grout, the elliptical sleeve withstood the maximum load required, with all the steel bar samples fracturing rather than pulling out of the grouted sleeve connector. These tests were conducted with bar diameters of 16 mm (T16 rebar), 20 mm (T20 rebar), and 25 mm (T25 rebar). The parameters of the testing are summarized in Table I. In all cases, the bars fractured at points outside the sleeve while the connection of the bars made by the elliptical sleeve remained intact. These results are graphically illustrated in
Specifically,
The various embodiments may be oriented vertically, horizontally or inclined depending on the connections to be made between between the overlapping reinforcing bars. Hardenable material generally of a cementitious grouting material or a suitable epoxy material can also be used. In some uses, the hardenable material can be placed into the sleeve through the end thereof before inserting the second overlapping bar, thereby eliminating the grout port holes in the sleeve.
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
