Reinforcing bar

1. A reinforcing bar for concrete reinforcing comprising:

a shaft extending along a portion of the length of the bar and a termination extending along an end portion of the bar, the termination being enlarged as compared to the shaft,

wherein the termination incorporates an engagement face incorporating locking formations thereon arranged to interfit with a complementary shaped termination to form an interlock arranged to accommodate axial loading,

wherein the locking formations comprise a plurality of spaced apart upstands extending transversely across the engagement face and a plurality of recesses disposed between adjacent ones of the upstands, each upstand includes opposite side walls interconnected by a bridging portion, and the opposing side walls of adjacent ones of the upstands defining respective ones of the recesses,

wherein the interlock extends along an axis and the side walls include:

bearing surfaces arranged to engage the complementary shaped termination in the interlock, the bearing surfaces extending at an angle of within 10° C. of the perpendicular to the direction of the interlock axis so that the reaction force at the interlock under axial loading does not induce separation of the terminations,

first transition regions being formed above respective bearing surfaces and forming the intersection between the bearing surfaces and the bridging portions, and

second transition regions extending from the respective bearing surfaces to base portions of the recesses, the first and second transition regions incorporating radii with the radius of the first transition regions being smaller than the radius of the second transition regions.

2. The reinforcing bar for concrete reinforcing according to claim 1 , wherein the termination is made integral with the shaft.

3. The reinforcing bar for concrete reinforcing according to claim 1 , wherein the termination is shaped to form an interlock with a complementary termination of identical shape to said termination.

4. The reinforcing bar for concrete reinforcing according to claim 3 , wherein the bearing surfaces extend at angle of within 5° C. of the perpendicular to the direction of the interlock axis.

5. The reinforcing bar for concrete reinforcing according to claim 1 , wherein the upstands are stepped downwardly along the engagement face towards the terminal end of the bar.

6. The reinforcing bar for concrete reinforcing according to claim 1 , wherein a first said upstand extends in the longitudinal direction of the termination a distance greater than a second said upstand.

7. The reinforcing bar for concrete reinforcing according to claim 1 , wherein said bar is formed from steel.

8. A coupling for interconnecting first and second reinforcing bars for concrete reinforcing, the coupling comprising:

first and second terminations extending along an end portion of the first and second reinforcing bars respectively, at least one of the reinforcing bars having its termination integrally formed with a shaft of that reinforcing bar and being enlarged as compared to that shaft, each termination including an engagement face incorporating locking formations thereon, the engagement faces of the terminations being opposing abutting relation with the locking formations interfitting to form an interlock,

wherein the locking formations comprise a plurality of spaced apart upstands extending transversely across the engagement face and a plurality of recesses disposed between adjacent ones of the upstands, each upstand includes opposite side walls interconnected by a bridging portion, and the opposing side walls of adjacent ones of the upstands defining respective ones of the recesses,

wherein the interlock extends along the axis and the side walls include:

bearing surfaces arranged to engage the complementary shaped termination in the interlock, the bearing surfaces extending at an angle of within 10° C. of the perpendicular to the direction of the interlock axis so that the reaction force at the interlock under axial loading does not induce separation of the terminations,

first transition regions being formed above respective bearing surfaces and forming the intersection between the bearing surfaces and the bridging portions, and

second transition regions extending from the respective bearing surfaces to base portions of the recesses, the first and second transition regions incorporating radii with the radius of the first transition regions being smaller than the radius of the second transition regions; and

a retaining device disposed around the interlock to retain the engagement faces in the opposing abutting relation to one another.

9. A coupling for interconnecting first and second reinforcing bars for concrete reinforcing, the coupling comprising:

first and second terminations extending along an end portion of the first and second reinforcing bars respectively, each termination being enlarged as compared to the shaft of the reinforcing bar, the terminations each including an engagement face incorporating locking formations thereon, the engagement faces of the terminations being in opposing abutting relation with the locking formations interfitting to form an interlock,

wherein the locking formations comprise a plurality of spaced apart upstands extending transversely across the engagement face and a plurality of recesses disposed between adjacent ones of the upstands, each upstand includes opposite side walls interconnected by a bridging portion, and the opposing side walls of adjacent ones of the upstands defining respective ones of the recesses,

wherein the interlock extends along the axis and the side walls include:

bearing surfaces arranged to engage the complementary shaped termination in the interlock, the bearing surfaces extending at an angle of within 10° C. of the perpendicular to the direction of the interlock axis so that the reaction force at the interlock under axial loading does not induce separation of the terminations,

first transition regions being formed above respective bearing surfaces and forming the intersection between the bearing surfaces and the bridging portions, and

second transition regions extending from the respective bearing surfaces to base portions of the recesses, the first and second transition regions incorporating radii with the radius of the first transition regions being smaller than the radius of the second transition regions; and

a retaining device disposed around the abutting terminations to retain the engagement faces in the opposing abutting relation to one another, wherein the coupling is arranged so that the interlock accommodates axial loading without inducing any substantial loading on the retaining device.

10. the coupling according to claim 9 , wherein the reinforcement bars further comprise shafts extending along a portion of their length, and wherein at least one of the terminations is made integral with its shaft.

11. The coupling according to claim 9 , wherein the retaining device is in the form of a sleeve.

12. The coupling according to claim 9 , wherein the sleeve is slidable over the abutting terminations.

13. The coupling according to claim 9 , wherein the sleeve has a shear strength that is greater than at least one of the reinforcing bars.

14. The coupling according to claim 9 , wherein the first and second terminations are of identical shape.

15. The coupling according to claim 9 , wherein the side walls incorporate bearing surfaces with the bearing surfaces of the first termination engaging with the bearing surfaces of the second termination in forming the interlock.

16. The coupling according to claim 9 , wherein the bearing surfaces extend at an angle of within 5° C. of the perpendicular to the direction of the interlock axis.

17. The coupling according to claim 9 , wherein in each termination, the upstands are stepped downwardly along the engagement face towards the terminal end of the respective bar.

18. The coupling according to claim 9 , wherein a first said upstand is wider than a second said upstand.

19. The coupling according to claim 9 , wherein the reinforcing bars are formed from steel.

20. The coupling according to claim 9 , wherein the retaining device is in the form of a sleeve.

21. A method of connecting first and second reinforcing bars for concrete reinforcing, the method comprising the steps:

interconnecting first and second reinforcing bars by forming an interlock between terminations formed on the end of the reinforcing bars, at least one of the reinforcing bars having its termination integrally formed with a shaft of that reinforcing bar being enlarged as compared to the shaft, the interlock being formed by interfitting locking formations formed on the respective terminations,

wherein the locking formations comprise a plurality of spaced apart upstands extending transversely across the engagement face and a plurality of recesses disposed between adjacent ones of the upstands, each upstand includes opposite side walls interconnected by a bridging portion, and the opposing side walls of adjacent ones of the upstands defining respective ones of the recesses,

wherein the interlock extends along the axis and the side walls include:

bearing surfaces arranged to engage the complementary shaped termination in the interlock, the bearing surfaces extending at an angle of within 10° C. of the perpendicular to the direction of the interlock axis so that the reaction force at the interlock under axial loading does not induce separation of the terminations,

first transition regions being formed above respective bearing surfaces and forming the intersection between the bearing surfaces and the bridging portions, and

second transition regions extending from the respective bearing surfaces to base portions of the recesses, the first and second transition regions incorporating radii with the radius of the first transition regions being smaller than the radius of the second transition regions; and

providing a retaining device about the interlock to retain the locking formations in interfitting relation.

22. A method of transferring load between first and second reinforcing bars for concrete reinforcing, the method comprising the steps of:

interconnecting the first and second reinforcing bars by forming an interlock between terminations formed on the end of the reinforcing bars, at least one of the reinforcing bars having its termination integrally formed with a shaft of that reinforcing bar and being enlarged as compared to that shaft, the interlock extending along an axis and being formed by interfitting locking formations formed on the respective terminations,

wherein the locking formations comprise a plurality of spaced apart upstands extending transversely across the engagement face and a plurality of recesses disposed between adjacent ones of the upstands, each upstand includes opposite side walls interconnected by a bridging portion, and the opposing side walls of adjacent ones of the upstands defining respective ones of the recesses,

wherein the interlock extends along the axis and the side walls include:

bearing surfaces arranged to engage the complementary shaped termination in the interlock, the bearing surfaces extending at an angle of within 10° C. of the perpendicular to the direction of the interlock axis so that the reaction force at the interlock under axial loading does not induce separation of the terminations,

first transition regions being formed above respective bearing surfaces and forming the intersection between the bearing surfaces and the bridging portions, and

second transition regions extending from the respective bearing surfaces to base portions of the recesses, the first and second transition regions incorporating radii with the radius of the first transition regions being smaller than the radius of the second transition regions; and

providing a retaining device about the interlock to retain the locking formations in interfitting relation; and

transferring loading through the interlock in the direction of the interlock axis without inducing any substantial load on the retaining device.