GB2169013A - Anchorage - Google Patents

Abstract

An anchorage 10, for casting into concrete comprises a, usually plastics casing providing a sleeve 14 having an open end 15 and a socket 13, 22 accommodating a non-circular body 12 having an internal threaded bore 18 coincident with sleeve 14, the thread of bore 18 being a coarse, quick release thread. <IMAGE>

Description

SPECIFICATION Anchorage This invention relates to an anchorage for casting into concrete to enable threaded members to be attached to a concrete structure easily and quickly.

The invention is particularly concerned with anchorages for use with tie bars used as temporary fastenings to hold and position shuttering, scaffolding, and like items during construction work.

The invention provides an anchorage, for casting into concrete, comprising a sleeve having one end open and having at its other end an enlarged non-circular socket accommodating a metal body having a threaded bore therein, said thread being a coarse quick release thread.

The metal body can be square in cross section and can fit inside a square socket, this arrangement ensuring that the body cannot turn in use under applied loads. The body can be triangular, rectangular or of any other convenient non-circular shape. It should be noted that a circular body would very likely turn in the socket by deformation of the material, usually plastics, thereof. A regular hexagonal body would very likely also turn under these circumstances and such shape is not suitable.

The thread is preferably a buttress thread of coarse pitch, such as iOmm for a nominal 20mm diameter bore. The thread can have a height of 1-1/2-2-1/2, preferably 2mm and a length of from 3-5mm. Such a thread can accommodate a range of threaded rods of similar but marginally different threads made by different manufacturers.

The body can be square in cross-section, from 25 to 35mm each side, preferably 30mm and should have a minimum axial length of 48mm. In practice a length from 5060mm can be chosen. The body can be of cast steel.

The sleeve with its socket can be united with a closed cap having a skirt which embraces the socket and is sealed thereto. The open end of the sleeve can be secured to shuttering before concrete is poured, either by use of a bolt having a complementary thread or a rod and nut, or by a separate screwed mounting. The open end of the sleeve can be provided with a protective mouthpiece to prevent attached rods damaging the concrete at the open end or being themselves damaged by the concrete.

The body can taper from a width of 2535mm at its end adjacent the sleeve, to a lesser width at its other end.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein: Fig. 1 is a longitudinal cross-sectional view through a preferred anchorage of the invention; and Fig. 2 is a fragmentary, similar view showing a variation.

A preferred anchorage (10) of the invention (Fig. 1) has three parts a sleeve 11, a body 12 and a cap 13. Sleeve 11 is of plastics material and has a circular tubular portion 14 of about 20mm internal diameter having an open end 15. The other end is formed with a square socket 16 delineated by side walls 17.

One end of square-sectioned body 12 is a close fit in cap 13 within the socket 16. Body 12 is of cast steel, square in section with side 30mm within cap 16 lapsing to 22-25mm at its other end. The body 12 is from 50 to 58mm iong and has a central threaded bore 18. The thread is a coarse, large pitch buttress thread having a pitch of about 10mm, a tooth height of about 2mm and a tooth root width of 6-7mm. This bore 18 will accommodate any of a plurality of complementary tie bars 19 (Fig. 2) of which several are manufactured having minor variations in size and thread shape, but all of the same pitch. Heretofore, tie bar 19 from a particular manufacturer has had to be used with a specific complementary socket from that manufacturer.

The present invention overcomes this difficulty.

The outer tapered surfaces of the body 12 contact correspondingly tapered sidewalls 22 of cap 13 which is also of plastics material and has square-wall end portions of side walls 22 which embrace the walls 17 of socket 16 and is sealed thereto by solvent welding. The closed end of cap 13 has a short closed cylindrical or squaresectioned recess 23 which can accommodate an end portion of an attached tie bar 19 and which may be filled by a body of grease for protection of the body 12 and inserted rod 19 in use. The body 12 is completely encased in plastics and is not subject to attack by chemicals from concrete in which the container is cast. The free end 15 of tubular portion 14 can be closed by a plastics or like cap when not in use to prevent ingress of water and dust.

To protect concrete 24 from damage (Fig.

2) by the bar 19 if bent and to protect the tie bar 19 from damage by the concrete 24, the open end of tubular part 14 can be provided with a mouthpiece 25 (Fig. 2) consisting of a conical body of plastics material having a central bore of the same or comparable size to that of tubular part 14 and a press fit in an end of part 14.

The anchorage of the invention provides a convenient simple, and robust attachment point for temporary members such as tie bars 19, scaffolding attachment bolts and the like used during construction. The coarse thread allows rapid and easy insertion of and removal of tie bars 19.

To obtain sufficient grip on bars 19 with the wide size tolerances between the bars 19 and the threads of bore 18, the axial length of body 12 should be at least two and a half, preferably three times the outer diameter of threaded rod 19. This can be stated alternatively, that the minimum length of body 12 should be at least three times the nominal diameter of bars 19. In the above embodiment the bars 19 are specified as being 15 or 16mm in diameter, that is the basic minimum bar diameter capable of load bearing, and the length of the socket 18 is 48mm minimum. A practical length will be from 50 to 60mm.

The tapering of body 12 saves material whilst maintaining its strength and function.

However, the body can have parallel side walls if desired.

The body 12 and the receiving plastics sheathing parts of the container constituted by parts of members 11 and 13 can be other than square-sectioned. A triangular-sectioned body could be used, but there would be a sharp contrast between the thickness of metal between the bore and the apices and that between the bore and the forces. A pentagonal body would be more complicated and closer to circular. A regular hexagonal body would be unsuitable, because it would have only a small difference between radially maximum and minimum dimensions, lending to allow turning under load. Oblong cross-sections or irregular shapes could be used, however, the more complicated the shape the more expense is involved. Also, parts serving solely to prevent rotation are effectively wasted material. What is needed is a body whose shape is compact to form a firm, strong anchorage for the threaded rod, combined with a reasonable degree of eccentricity giving good resistance to turning. A square body is an optimum shape, but, of course, some departure from this idealis possible.

Different sizes of bodies with different diameters of bores can serve to connect with bars of different sizes.

The mouthpiece 25 can, for example when the bar will bear a shear load parallel to the concrete surface, be removed after casting of the concrete and replaced by a similarly shaped annulus of metal or comparable material capable of receiving a shear load from a bar and transmitting it to a wide area of the concrete.

Claims (22)

1. An anchorage, for casting into concrete, comprising a sleeve having one end open and having at its other end an enlarged non-circular socket accommodating a metal body having a threaded bore therein, said thread being a coarse, quick release thread.

2. An anchorage as claimed in claim 1, wherein the body is square in cross section and fits inside a square socket.

3. An anchorage as claimed in claim 1, wherein the body is triangular or oblong in cross-section.

4. An anchorage as claimed in claim 1, 2 or 3, wherein the thread is a buttress thread of coarse pitch.

5. An anchorage as claimed in claim 4, wherein the pitch is 10mm for a nominal 20mm diameter bore.

6. An anchorage as claimed in claim 5, wherein the thread has a height of 1-1/2-2- 1/2mm.

7. An anchorage as claimed in claim 6, wherein the thread height is 2mm.

8. An anchorage as claimed in any of claims 4 to 7 wherein the thread has a length of from 3 to 5mm.

9. An anchorage as claimed in claim 2 wherein the body measures from 25 to 35mm each side.

10. An anchorage as claimed in claim 9 wherein the body measures 30mm on each side.

11. An anchorage as claimed in any of claims 4 to 10 and having a minimum axial length of 48mm.

12. An anchorage as claimed in claim 11 and being from 50 to 60mm in length.

13. An anchorage as claimed in any preceding claim wherein the body is of cast steel.

14. An anchorage as claimed in any preceding claim wherein the sleeve and socket are united by a closed cap having a skirt which embraces the socket and is sealed thereto.

15. An anchorage as claimed in any preceding claim wherein an open end of the sleeve is adapted to be securable to shuttering before concrete is poured.

16. An anchorage as claimed in claim 15 wherein such securement is affected by use of a bolt having a complementary thread, by a rod and nut, or by a separate screwed mounting.

17. An anchorage as claimed in any preceding claim wherein an open end of the sleeve is provided with a surrounding mouthpiece which forms and occupies an annular recess in the concrete surrounding the sleeve.

18. An anchorage as claimed in claim 17 wherein the surrounding mouthpiece remains in position and serves to prevent contact between a rod and the concrete to prevent or reduce damage.

19. An anchorage as claimed in claim 17 when used to bear shear force from a bar, the mouthpiece being removed after casting of the concrete and replaced with an annulus of metal or comparable material capable of receiving a shear load from the bar and transmitting it to an area of the surrounding concrete.

20. An anchorage as claimed in any preceding claim wherein the body tapers from a front to a rear end thereof.

21. An anchorage as claimed in claim 20 wherein the parts of the sleeve encasing the body are complementarily tapered.

22. An anchorage substantially as hereinbefore described with reference to the accompanying drawings.