This invention relates to coupling device and method for coupling reinforcing bars or prestressing wires in end to end relationship, and more particularly to a coupling device and method for coupling reinforcing bars or prestressing wires in a concrete structure which does not require rotation of the bars or wires or require the use of any tools.

Generally reinforced concrete is concrete containing steel reinforcing bars (often abbreviated to "rebar"), whereby the concrete bears compressive forces and the reinforcing bars bear tensile forces. The term reinforcing bar used hereinafter is also intended to emcompass steel wires or tendons used to prestress a concrete structure.

It is often necessary to assemble separate precast concrete sections, for example in concrete piles, wherein it is necessary to interconnect multiple pile sections in end to end relationship as the pile is driven into the ground. In circumstances it is necessary to couple or splice together the reinforcing bars of adjacent concrete sections so that the reinforcing bars can resist tension and bending forces applied to the joint between the sections.

Many known methods of splicing together reinforcing bars typically require access to the ends of the bars for the use of tools to tighten threaded fasteners, to weld the ends of the bars together or to swage a connector device over the abutting ends of the bars. However, where abutting faces of adjacent concrete sections are flush fitting such access may not be available. This is a particular problem when joining reinforced concrete pile sections.

Attempts to solve such problem have resulted in complex and costly arrangements, such as the ABB, Westpile or Kie-Lock joints, where specially shaped steel plates or castings are precast into the pile ends to define male and female couplings that are interconnected by locking pins or specially shaped connectors.

An object of the present invention is to provide a simple, cost effective and reliable way of coupling reinforcing bars of adjacent precast concrete sections which overcomes the above problems.

According to a first aspect of the present invention there is provided a coupling assembly for coupling reinforcing bars or prestessing wires in end to end relationship, said assembly comprising a first coupling part formed on or mounted on an end of a first reinforcing bar and a second coupling part mounted on, or otherwise coupled to, an end of a second reinforcing bar adjacent said end of said first reinforcing bar, said first and second coupling parts comprising respective male and female members provided with co-operating retaining barbs or teeth, whereby said first coupling part can be engaged with said second coupling part to couple said first and second reinforcing bars by relative axial displacement of said first and second reinforcing bars without rotation thereof.

Preferably said co-operating retaining barbs or teeth are formed with a saw tooth profile to facilitate insertion of said male member into said female member while resisting removal of said male member from said female member once inserted therein.

The retaining barbs or teeth may be in the form of circumferentially extending axially spaced teeth or helically extending threads formed on respective ends of said first and second coupling parts.

Preferably the second coupling part comprises an elongate sleeve, the or each end of the sleeve being provided with at least one axially extending slot or opening to permit radial expansion or compression thereof to enable said first coupling part to be engaged with said second coupling part by respective axial displacement of said first and second coupling parts. The sleeve may be provided with a longitudinal slot extending along the length of the sleeve from end to end.

In one embodiment, at least a portion of said first coupling part may be received over an end of said first reinforcing bar to secure the first coupling part thereon. Said first coupling part may comprise a tubular member adapted to be mounted over said end of said first coupling part and to be secured thereto, for example by crimping, welding or adhesive. Said retaining barbs or teeth may be formed externally at one end of said sleeve defining said second coupling part, said barbs or teeth being engageable with co-operating retaining barbs or teeth formed internally on an end of said tubular member defining said first coupling part.

In an alternative embodiment, the first coupling part may be integrally formed on said end of said first reinforcing bar. The first coupling part may comprise retaining barbs or teeth integrally formed on said end of said first reinforcing bar engageable with co-operating retaining barbs or teeth formed internally in an end of said sleeve defining said second coupling part. At least a portion of said first coupling part may be received over an end of the first reinforcing bar to secure the first coupling part thereon. Said second coupling part may be coupled to an end of said second reinforcing bar by means of a further coupling part formed on or mounted on said end of said second reinforcing bar. The further coupling part and said second coupling part may define respective male and female members provided with co-operating retaining barbs or teeth, whereby said further coupling part can be engaged with said second coupling part by relative axial displacement of said further and second coupling parts.

In one embodiment, the further coupling part may comprise a tubular member adapted to be mounted over said end of said second coupling part and to be secured thereto, for example by crimping, welding or adhesive. The further coupling part may comprise retaining barbs or teeth integrally formed on said end of said first reinforcing bar engageable with cooperating retaining barbs or teeth formed on said second coupling part.

According to a further aspect of the present invention there is provided a coupling assembly for coupling reinforcing bars or prestressing wires in end to end relationship, said assembly comprising a sleeve having barbs or teeth formed internally at opposite ends thereof for receiving co-operating retaining barbs or teeth formed on respective ends of said reinforcing bars, wherein the retaining barbs or teeth are formed with a saw tooth profile such that said end of said at least one bar can be engaged with the sleeve by relative axial displacement of the bar and the sleeve without rotation of the bar or sleeve.

According to a further aspect of the present invention there is provided a method of coupling reinforcing bars or prestressing wires in end to end relationship comprising the steps of forming saw tooth configured retaining barbs or teeth on an end of at least one of the reinforcing bars, providing a sleeve having radially expandable portion adjacent at least one end thereof having saw tooth configured retaining barbs or teeth formed internally thereof adapted to cooperate with the respective saw tooth configured retaining barbs or teeth of said end of at least one of said bars, and axially engaging the end of said least one reinforcing bar with the sleeve by relative axial displacement of the at least one reinforcing bar with respect. In a further aspect there is provided a coupling assembly for coupling reinforcing bars in end to end relationship, said assembly a sleeve having internal threads at opposite ends thereof for receiving correspondingly threaded ends of said reinforcing bars, wherein said threaded end of at least one of the reinforcing bars and the corresponding internally threaded of the sleeve are formed with a saw tooth profile such that said threaded end of said at least one bar can be engaged with the sleeve by relative axial displacement of the bar and the sleeve without rotation of the bar or sleeve. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which :-

Figure 1 is a longitudinal sectional view of a reinforcing bar coupling assembly according to a first embodiment of the present invention;

Figure 2 is a detailed sectional view of the coupling assembly of Figure 1;

Figure 3 is a detailed view of the thread profile of the coupling assembly of Figure 1; Figure 4 is an end view of the sleeve of the coupling assembly of Figure 1;

Figure 5 is a perspective view of a reinforced concrete pile assembly incorporating the reinforcing bar coupling assembly of Figure 1; Figure 6 is a further perspective view of a reinforced concrete pile assembly incorporating the reinforcing bar coupling assembly of Figure 1;

Figure 7 longitudinal sectional view of a reinforcing bar coupling assembly according to a second embodiment of the present invention;

Figure 8 is an exploded view of the coupling assembly of Figure 7; and Figure 9 is a longitudinal sectional view through part of a coupling assembly in accordance with a further embodiment of the present invention for attachment to prestressing tendons or wires. A coupling assembly for coupling adjacent ends of reinforcing bars in end to end relationship in accordance with a first embodiment of the present invention is illustrated in Figures 1 to 4.

Coaxially arranged steel reinforcing bars 10,20 arranged to be coupled in end to end relationship have threads 12,22 or axially spaced circumferentially extending teeth cut or rolled into each end 14,24 thereof. As best seen from Figure 3 the threads or teeth 12,22 of each end 14,24 of the respective bars 10,20 have a saw tooth profile, defining an inner flank 30 arranged substantially perpendicular to the axis of the bar and an outer flank 32 arranged at a relatively shallow angle to the axis of the bar.

The ends 14,24 of the bars 10,20 are coupled together by means of a tubular cylindrical sleeve 40 formed from a resilient material, such as spring steel, the sleeve 40 having internally threaded or toothed ends 42,44 shaped and dimensioned to engage the teeth or threads 12,22 of respective ends 14,24 of the bars 10,20.

The cross sectional profile of the ends 14,24 of each bar 10,20 and the corresponding portions 42,44 of the sleeve 40 are arranged such that the ends 14,24 of the bars 10,20 can be axially pushed into the corresponding ends 42,44 of the sleeve 40, the shallow angled outer flanks 32 of the threads or teeth formed on the ends 14,24 of the bars 10,20 and the co- operating threaded or toothed portions 42,44 of the sleeve 40 sliding past one another, while the perpendicular inner flanks 30 of the threads or teeth formed on the ends 14,24 of the bars and the corresponding threaded or toothed portions 42,44 of the sleeve 40 abut one another to prevent the ends of the bars 10,20 from being pulled out of the sleeve 40, once engaged therewith.

In this manner the sleeve 40 becomes a tensile extension of the reinforcing bars 10,20, coupling the sleeves 40 in coaxial end to end relationship, ensuring continuity of the coupled reinforcing bars. As can be seen from 4, the sleeve 40 is provided with an axially extending slot 46 from end to end to allow the sleeve 40 to be expanded to assist insertion of the ends of the bars 10,20 into the sleeve 40. As shown in Figures 1 and 2, the ends 14,24 of the bars 10,20 and the sleeve 40 are chamfered to assist insertion of the threaded ends 14,24 of the bars 10,20 into the sleeve 40.

An internally projecting shoulder or stop 48 may be provided in a central region of the sleeve 40 to limit the insertion depth of the bars 10,20 into the sleeve 40.

The use of the coupling assembly of Figures 1 to 4 to couple reinforcing bars of precast concrete pile sections is illustrated in Figures 5 and 6.

As can be seen from Figure 6, a sleeve 40 is first engaged with each end of the reinforcing bars 10 of the lower pile section 5 OA. Where the ends of the bars and corresponding portions of the sleeves 40 are threaded, the sleeves 40 may be engaged with the lower reinforcing bars 10 by screwing the sleeves 40 onto the bars 10.

As the upper pile section 50B is lowered onto the lower pile section 50A, the ends 24 of the reinforcing bars 20 of the upper pile section 50B are guided into the upper ends of the sleeves 40. Subsequently the weight of the upper pile section 50B causes the ends of the reinforcing bars 20 to be forced into the upper ends of the sleeves 40, the axial slot 46 in each sleeve 40 allowing the sleeves 40 to expand to permit the sloping flanks 32 of the threads or teeth to slide past one another such that the threaded or toothed formations of the ends 24 of the bars 20 to engage the corresponding threaded or toothed ends of the sleeves 40 by relative axial displacement of the bars and sleeves.

Once the ends 24 of the bars 20 are engaged within the co-operating portions of the corresponding sleeves 40, the perpendicular flanks 30 of the thread or teeth engage one another to prevent the bars 20 from being pulled out of the sleeves 40, thus enabling the coupled bars 10,20 to withstand tensile forces.

Once the pile sections 50A, 50B are assembled, any remaining voids around the coupling assemblies may be filled by an epoxy, resin or cement filler/adhesive. A coupling assembly in accordance with a second embodiment of the present invention is illustrated in Figures 7 and 8. In the first embodiment illustrated in Figures 1 to 6 it is necessary to form saw tooth shaped teeth or threads in the end portions 14,14 of the reinforcing bars 10,20. Where the reinforcing bars are formed from low grade or recycled materials such may cause difficulties. Furthermore, the requirement to cut threads or teeth into the ends of the reinforcing bars and also makes the coupling assembly unsuitable for use with prefabricated pile structures without first machining the ends of the reinforcing bars.

In a second embodiment of the invention, illustrated in Figures 7 and 8, this problem is solved by providing a three part coupling assembly comprising a pair of tubular coupling members 114,124 adapted to be fitted over respective ends of adjacent reinforcing bars 100,200, each tubular coupling member 114,124 having a first end defining a tubular portion 115,125 for receiving an end of a respective reinforcing bar 100,200 and a second end adapted to receive a co-operating end of a coupler in the form of a sleeve 140, the respective second ends of the respective coupling members 114,124 and the co-operating portions of the sleeve 140 having co-operating saw-tooth profile toothed or threaded portions 112,122,142,144 such that the reinforcing bars 100,200 can be coupled by relative axial displacement of the coupling members 114,124 and sleeve 140, as will be described in more detail below.

The tubular first end 115,125 of each coupling member 114,124 may be secured onto the end of the respective reinforcing bar 100,200 by crimping. Alternatively the coupling members 114,124 may be secured to the ends of the reinforcing bars by welding or suitable adhesive.

The second end of each coupling member 114,124 defines a female coupling part having a saw tooth profile toothed or threaded portion 112,122 formed internally therein adapted to receive a respective end of the sleeve 140. Co-operating external toothed or threaded regions 142,144 of the sleeve 140 engage the toothed or threaded portions 112,122 of the respective coupling member 114,124 to retain the sleeve 14 within the coupling members 114,124, thus securing the ends of the reinforcing bars together. Alternatively it is envisaged that said toothed or threaded portion of each coupling member may be formed on an external face thereof, the co-operating toothed or threaded portion of the sleeve being formed on an internal face of the sleeve, such that the sleeve 140 is fitted over the ends of the coupling members 114,124 in similar fashion to the first embodiment shown in Figures 1 to 6.

As with the first embodiment, the sleeve 140 may be formed from spring steel and is provided with an axially extending slot 146 enabling the sleeve 146 to be radially compressed to assist insertion of the ends of the sleeve 140 into the receiving female portions of the coupling members 114, 124.

It is envisaged that the sleeve 140 may be fitted directly to the end of one of the reinforcing to be coupled, for example by crimping the sleeve over the end of the bar, the other end of the sleeve being coupled to the end of the other reinforcing bar by means of a coupling member as described above (or by providing a threaded or toothed end on the other bar to be received in the sleeve).

The coupling assembly and method according to the present invention may also be used to couple steel wires or tendons used to prestress concrete structures. Such wires are typically much thinner than reinforcing bars and are generally under greater tension. Therefore it is generally not possible to form teeth or threads in the ends of the wires, as in the embodiment shown in Figures 1 to 6, or to simply crimp the coupling members onto the ends of the wires, as in the embodiment shown in Figures 7 and 8. In a modified embodiment, shown in Figure 9, the coupling assembly comprises a pair of coupling members 224 (only one) that can be attached to the respective ends of adjacent prestressing wires to be coupled, each coupling member 224 having teeth or threads 222 formed on an inner face thereof for engagement with a coupling sleeve (not shown) in the same manner as the coupling assembly of Figures 7 and 8. In this modified embodiment, an end 225 of each coupling member 224, opposite the toothed or threaded portion 222, comprises a through bore with a narrowed neck region 230 through which the prestressing wire 300 can pass with a close fit. Once it has been passed though the neck region 230 of the coupling member 224, the distal end 310 of the wire can be peened or otherwise formed into a widened button head region, having a diameter greater than that of the neck region 230 to retain the coupling member 224 onto the wire 300.

The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention. Whilst coupling assemblies in accordance with the present invention have been described in relation to the coupling of reinforcing bars and prestressing wires extending between abutting reinforced concrete structures, a coupling assembly in accordance with the present invention may be used to couple reinforcing bar sections or prestressing wires within a reinforced concrete structure prior to casting or in other applications wherein it is desired to couple coaxially arranged reinforcing bars or wires, particularly, but not exclusively, in concrete structures. Furthermore, while the present invention has been described in relation to the coupling of steel reinforcing bars it may also be used to couple reinforcing bars made from other materials, such as composite materials, including fibre reinforced polymer (FRP) bars. It is also envisaged that the coupling assembly and method according to the present invention may be utilised to couple coaxially arranged bars, rods or wires in many other applications.