AU642641B2 - Anchors - Google Patents

Description

I I ~-1 OPI DATE 09/10/90 AOJP DATE 15/11/90 APPLN. ID 51701 PCr PCT NUMBER PCT/AU90/00071 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 90/10763 E04B 1/41, E04G 21/16 Al B66C 19/02 (43) International Publication Date: 20 September 1990 (20.09.90) (21) International Application Number: PCT/AU90/00071 (74) Agents: HIND, Raymond, Stenton et al.; Davies Collison, 1 Little Collins Street, Melbourne, VIC 3000 (AU).

(22) International Filing Date: 23 February 1990 (23.02.90) (81) Designated States: AT (European patent), AU, BE (Euro- Priority data: pean patent), CA, CH (European patent), DE, DE (Eu- PJ 3087 7 March 1989(07.03.89) AU ropean patent), DK (European patent), ES (European PJ 6910 18 October 1989 (18.10.89) AU patent), FR (European patent), GB, GB (European patent), IT (European patent), JP, LU (European patent), NL (European patent), SE (European patent), US.

(71) Applicant (for all designated States except US): RAMSET FASTENERS (AUST.) PTY. LIMITED [AU/AU]; Maroondah Highway, Croyd6n North, VIC 3136 Published With international search report.

(72) Inventors; and Inventors/Applicants (for US only): PATERSON, Ian [AU/ AU]; 4 Saville Street, Ferny Creek, VIC 3786 FIN- LAY, Michael [AU/AU]; 111 Lake Road, Nunawading, VIC 3131 (AU).

(54) Title: ANCHORS (57) Abstract A lifting anchor for incorporation into a concrete component during casting comprises a head portion (2) with a lifting eye which remains exposed and a body portion which is embedded within the concrete. The body portion is of truncated form to provide a substantial anchorage effect within the concrete. The body portion may be of conical or pyramid shape or may comprise a series of axially spaced cones or pyramids. Alternatively the body portion may be of bifurcated construction with two substantial parallel legs (42) each of which is shaped with a wave-like profile to define a series of truncated forms.

r I 'WO 90/10763 PCT/AU90/00071

'ANCHORS"

The present invention relates to anchors and more particularly to lifting anchors for incorporation into formwork for concrete beams or slabs prior to pouring the concrete in order to define lifting points by which the cast beam or slab can be lifted on site.

Prior lifting anchors for incorporation into precast slabs or beams generally fall into two categories.

One category consists of a so-called "face-lif' t ahchor which is incorporated into the thickness of a slab so as to provide a lifting point on the large face of the slab.

The second category is a so-called "edge-lift" or "erection" anchor which is incorporated into an edge of a slab, a beam or other component. In each case, a head of the anchor, usually incorporating a lifting eye for engagement with a lifting shackle, is located with a recess formed in the surface of the component.

One previously proposed form of face-lift anchor comprises a flat bar which is anchored within the slab by means of a circular-section pin which is embedded with the bar within the thickness of the slab and extends transversely through an aperture in the bar. When a lifting load is applied to the anchor, the transverse anchoring pin applies a tensile and shear load to the surrounding concrete of the slab. The anchorage is mainly dependent on the size of pin and the depth of embedment.

As concrete is relatively weak in tension, the tensile forces applied by the pin to the concrete reduce the allowable loads which can be applied to the anchorage and this effect is particularly prevalent with thin panels where there is a reduced depth of embedment.

iVq ~e~,~mrrrrrrrrrr~ llrr~i~ll~l~~ arrrrr* i i~ -2- Edge-lift or erection anchors conventionally comprise a flat bar having at its inner end splayed feet which diverge from opposite sides of the bar. The anchorage provided is satisfactory only if the anchor is surrounded by a sufficient thickness of concrete. If the anchor is used with relatively thin slabs or beams, either the allowable load falls considerably or additional reinforcing steel must be provided for co-operation with the anchor. The splayed feet also tend to deflect towards the axis of the anchor when subjected tu the lifting loads, and this can lend to a decrease in the anchoring effect.

An object of the invention is to provide lifting anchors which provide a more secure anchorage within the concrete so as to permit an increased allowable load even under adverse anchoring conditions.

According to the present invention there is provided a lifting anchor for incorporation within a concrete component during casting of the component to provide a lifting point for the component, said anchor comprising a head portion adapted to remain exposed for engagenient by lifting means and a body portion for embedment within the concrete, at least part of the body portion having a plurality of truncated forms with S: 25 opposed sides which diverge in an axial direction away from the head portion, said truncated forms being of such an extent as to provide substantial anchorage within the concrete, and said truncated forms being such that collapse of the form by deformation of the sides of the form during lifting is prevented, each truncated form being displaced axially from an adjacent truncated form, and the sides of the form being *inclined to the longitudinal axis of the anchor at an angle of inclination of between 5 and I 35 Further according to the invention, there is provided a lifting anchor fo- incorporation within a concrete component during casting of the component to provide a lifting point for the component, said anchor comprising a head portion adapted to remain at least partly exposed for engagement by lifting 1 ~1-rh~'nc- _1 u -3means and a body portion for embedment within the concrete, said body portion being shaped to cause secure anchorage of the anchor within the concrete under the lifting loads, said shape comprising a plurality of solid truncated forms having opposed sides which diverge in an axial direction away from the head portion, said truncated forms extending along at least a majority of the length of the body portion and having such a lateral extent that the or each truncated form constitutes the primary means for securing anchorage within the concrete; and said truncated forms being such that collapse of the form by deformation of the sides-of the form during lifting is prevented, each truncated form being displaced axially from an adjacent truncated form, and the sides of the form being inclined to the longitudinal axis of the anchor at an angle of inclination of between 5 and Still further according to the invention, the:e is provided a lifting anchor for incorporation within a concrete component during casting of the component to provide a lifting point for the component, said anchor comprising a head portion having an eye which remains exposed for engagement by lifting means extending through the eye, and a body portion for embedment within the concrete, said body portion being shaped S to cause secure anchorage of the anchor within the concrete 25 under the lifting loads wherein said heaC rtion is of platelike form with the eye being formed by an aperture extending through the plate-like head portion at right angles to the major surfaces of the head portion and the body portion being shaped to define a plurality of truncated forms having upwardly facing opposed sides which diverge in an axial direction towards the base of the anchor, said divergent sides extending at least in the planes containing the major surfaces :I of the head portion, and the size and extent of the truncated forms being such that the forms provide substantial anchorage 35 of the body portion within the concrete, and said truncated forms being such that collapse of the form by deformation of the sides of the form during lifting is prevented, each truncated form being displaced axially from an adjacent 1 truncated form, and ths sides of the form being inclined to -r -4the longitudinal axis of the anchor at an angle of inclination of between 5 and Preferably, the opposed sides of the truncated forms are inclined to the longitudinal axis of the anchor by an angle of between 10 and 40*, and an angle of about 30* being the optimum.

In a preferred embodiment, each truncated portion of the body may be of a pyramid shape or a conical shape.

An embodiment of the anchor for use as a face-lift anchor wherein the head portion is incorporated in a face of a slab, may comprise an integral stand projecting from the base of the anchor to support the anchor from the base of a mould for the slab, with the base of the anchor being spaced above the base of the mould.

An embodiment of the invention for use as an edge-lift anchor for incorporation into the edge of a slab or beam is of bifurcated form comprising two substantially parallel legs depending from the head portior. Each of the legs has opposed sides profiled to define a series of axially spaced truncated forms with opposing sides which diverge away from the head S 25 portion.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:- 93 81 5.45 ,11 Figure 1 is a front view of an embodiment of a lifting anchor in accordance with the invention; Figure 2 is a side view of the anchor shown in Figure 1; Figure 3 is a iZragmentary side view of an edge-lift anchor; Figure 4 is an enlarged view showing in detail the profile formed on the legs of the anchor shown in Figure 3; and Figure 5 is an elevation of another embodiment of an edge-lift anchor.

As shown in Figures 1 and 2, a f irst embodiment of a 'S lifting anchor in accordance with the invention comprises a head portion 2 of flat plate like form of rectangular crosssection with an aperture 4 extending at right angles through the plane of the head portion to define a lifting eye.

Axially inwardly of the head portion 2, the body 6 of the anchor comprises a series of axially-spaced truncated forms interconnected by relatively short inwardly-directed wall i portions 12 preferably at right angles to the outwardly divergent sides 14. In the particular form shown, the body I' *.comprises a series of three truncated forms, although there may only be two. It may sometimes be desirable to provide uslm a~m~lr~r~clrrrrrr~ ii

I

-6more than three truncated forms (for example up to FAout six), although two or three will usually suffice. The use of a series of truncated forms apply, when a lifting force is acting on the anchor, a compressive and shear load to the surrounding concrete and for a given length of anchor, requires less material in manufacture than would a single truncated form. The loading in compression and shear provides a significantly greater anchoring force than the loading in tension and shear as provided by the anchoring pin of the face-lift anchor discussed at the outset.

We have determined that to provide effective anchoring, the angle of inclination of the inclined sides to the longitudinal axis of the body should be between 5 and 50° with a range of between 10 to 40° providing good results. We have j determiined that an inclination of about 30° provides optimum i results. The anchor may be fully moulded from a suitable plastics such as nylon or may comprise a composite of a plastics moulding around a bar-like steel core which is Si apertured at the head end to provide the lifting eye.

i, ;C I( I -7- In the anchor shown, the body portion is directly connected to the head portion. For some applications it may be necessary for the body portion to lie at a substantial depth within the concrete with a relative long shaft extending between the body portion and the head portion at the surface of the component.

The anchor shown can be used as an edge-lift anchor for incorporation into an edge of a slab or for incorporation into UI a beam.

The anchor can also be used as face-lift anchors. For this purpose, the anchor is used in conjunction with a stand 'having downwardly protecting feet by which the anchor is supported from the base of the mould for the slab whereby the bottom of the anchor body will be spaced at a suitable I ;"distance above the bottom face of the slab or panel after casting. Although it is possible to utilise a separate stand to which .the anchor can be clipped or otherwise secured, it S is possible to provide the anchor with an integral stand, which is produced with the anchor preferably in a single Smoulding operation.

i l i -8- There is shown in Figures 3 and 4 an edge-lift anchor which is of bifurcated form to provide two parallel legs depending from a head portion 32 having a lifting eye 34. The head portion also includes a recess 36 at each side for receiving part of the reinforcement. The anchor is of constant thickness as viewed from the side and is preferably formed by cutting from metal plate, for example by means of a plasma arc process.

Each of the two legs 30 of the anchor is formed with a multiplicity of truncated formations which extend only in the width dimension of the legs whereby the legs are of constant thickness. These formations, although extending in one plane only, are similar to those considered in relation to Figures 1 and 2 and the previous discussion concerning suitable angles of inclination are appropriate also to this anchor. Again, the optimum angle of inclination is 30 degrees. Whereas in the anchor of Figures 1 and 2 each truncated form is defined by 4 4r

LI

44 4 4 444' 4 4 S6 4 0 A. I 4' axis of the body, in the anchor of Figures 3 and 4, the wavelike profiles on the opposite sides of each leg 30, although of mirror image, are dxially displaced one relative to the other so that the cres,,ts 38 and troughs 40 of the two profiles are not in axial aulignment as is clearly shown in Figure 4.

This axial misalignment between the two profiles has two effects. Firstly, it prevents the formation of relatively narrow lands which would otherwise exist at the points of coincidence of two opposed troughs 40 and which might therefore create zones of weakness along th3 length of the leg. Secondly, it permits a series of anchors, to be cut simultaneously from the same plate, with the stock between the inner surfaces of the two legs of one another forming the opposed surfaces of the leg of a second anchor which is cut from the plate in inverted relatio to the first anchor.

Preferably, the axial. misalignment of the two profiles is approximately ocue-half of the distance between adjacent crests of the profiles.

The bifurcated form of this edge-lift anchor enables the legs 30 to lie on opposite sides of reinforcing rods WO 90/10763 PCT/AU90/00071 10 and reinforcing mesh without having to cut any of the reinforcement. In contrast, edge-lift anchors of solid construction across their width may sometimes require the reinforcement to be cut in order to permit the anchor to be placed within the mould at the required position.

s The edge-lift anchor shown in Figure Affis of bifurcated form similar to that of Figures^l and 32to provide two legs 42 depending from a head portion 44 having a lifting eye 46. The head portion 44 includes a recess 48 at each side for receiving part of the reinforcement. The anchor is of constant thickness as viewed from the side and is preferably formed by cutting from metal plate, for example by means of a plasma-arc process. Each of the two legs 42 of the anchor is formed with a multiplicity of truncated. .(that is, divergent) formations, the flanks of which are inclined to the longitudinal axis of the leg at a range of angles (alpha) as discussed above an optimum angle of inclination (alpha) being 30*. The outer profile 50 of each leg 42 is defined by a wave-like formation having alternating peaks and troughs of arcuate section symmetrical about an axis at right angles to the longitudinal axis of the formation, whereas the inner profile tis defined by a wave-like formation of which one flank 12a is of rectilinear shape.

The symmetrical outer profiles 50 facilitates manufacture of anchors simultaneously from a single plate whereby the stock between the two legs of one anchor forms two legs each associated with a different one of two anchors in inverted relation to the first anchor, and this manufacturing configuration requires the outer profile of each leg to be symmetrical in either orientation.

ii WO90/10763 PCT/AU90/00071 -11- In the configuration shown in Figures and 1, the axes of the inner and outer wave-like profiles of each leg are parallel so that the two legs of the anchor are effectively parallel. Expressed differently, the crests of the wave-like formations on the inner and outer surfaces of each leg lie on a respective one of two parallel planes. In contrast, in the anchor of Figure P, a line passing through the crests of the wave-like formation on the inner surface of the leg is inclined relative to thet of a line passing through the crests of the outer wave-like formation so that the leg progressively tapers in width from the head end to the foot end of the anchor. We have determied that the legs carry a decreasing proportion of the load with increasing distance from. the surface of the component in which the anchor is embedded. As the load carried by the leg decreases with increasing distance from the head end of the anchor, the width of the leg can therefore be progressively reduced away from the head end without impairing the load-carrying capabilities of the anchor.

Gener l 1 ly speaking, the angle of taper (beta) will be up to 15 degrees, the higher end of the range being used for anchors where the legs are relatively short (about 150mm) and the wave-like formations have large amplitude. For most situations, for an anchor with a 5 tonne swl and a leg length of between about 300 and 400mm, taper angles of up to about 5° would be adequate. What is important is that the length of the portion of the legs with the wave- 0O like formations is sufficient to transfer the load from the anchor to the concrete. The taper which provides the progressive reduction in width permits, for an anchor with a given load-bearing capacity, a reduction cost of the anchor due to savings in material. The incl.n\ation which provides the taper is provided preferably only on the inner surface oi each leg.

W090/0763PCT/AU9O/00071 -12 3Ithough it is pref err~d that the anchors of Figures kT to I.Ihave wave like profiles at the opposite sides of each leg to2 provide the truncated forms, one side of each 4leg, preferably the inner side, could be rectilinear and parallel Q-o the longitudinal axis of the leg. This would still provide a series of truncated forms with divergent sides, although the anchoring effect will be diminished to an extent; however, manufacture would be simplified.

lhe anchors described~ herein are embedded into a beam or slab, with the head of the anchor lying in a recess formc-d in the surface of the beam or slab so that the eye can be engaged with a lifting shackle of a lifting cable. The recess is produced during casting of the beam or slab by means of a removable recess former placed over the anchor head, os is well known.

In the embodiments described the truncated form or forms on the body portion are such as to provide at least a significant part, and sometimes the whole, of the anchorage for the anchor within the concrete, the size, and in par cicular the lateral t ent of the few forms being sufficient for this purpose. It is then not essential to add furth(er -einforcement within the concrete to co-operate with the anchor to provide the required load-carrying characteristics. It will be noted that each truncated form is solid in order to prevent collapse of the, truncation by deformation or bending of the sides of the truncation towards the longitudinal axis of the anchor under the forces applied during lifting, Although the solid structure is the simplest means of reinforcing truncated structurf-Aagainst collapse, other forms of reinforcing structure would be possible.

The embodiments have been describad by way of example only and modifications are possible within the scope of the invention.

Claims (17)

1. A lifting anchor for incorporation within a concrete component during casting of the component to provide a lifting point for the component, said anchor comprising a head portion adapted to remain exposed for engagement by lifting means and a body portion for embedment within the concrete, at least part of the body portion having a plurality of truncated forms with opposed sides which diverge in an axial direction away from the head portion, said truncated forms being of such an extent as to provide substantial anchorage within the concrete, and said truncated forms being such that collapse of the form by deformation of the sides of the form during lifting is prevented, each truncated form being displaced axially from an adjacent truncated form, and the sides of the form being inclined to the lon!itudinal axis of the anchor at an angle of inclination of b -et.en 5 and

2. An anchor according to Claim 1, wherein each truncated form has divergent sides in at least two mutually inclined axial planes.

3. An anchor according to Claim 2, wherein each truncated form is of substantially pyramid shape or substantially conical shape.

4. An anchor according to Claim 1, wherein the body portion of the anchor is of substantially constant axial thickness in one axial plane and ear- truncated form is defined within a second axial plane at rht angles to the said one plane.

5. An anchor according to any one of Claims 1 to 4, wherein each truncated form is formed by moulding around a core element within the body portion, said core element extending into the head portion of the anchor and being apertured to provide a lifting eye in the head portion. 930813,p:\oper\rshancho rpe,13 -14-

6. An anchor according to any one of Claims 1 to 5, wherein the anchor has, at a lower end of the body portion remote from the head portion, an integral stand of larger lateral extent that the body portion and operative to support the anchor from the base of a mould for the concrete component with the lower end of the body portion spaced above the base of the mould.

7. An anchor according to Claim 1 for incorporation into an edge of a concrete slab or beam, said anchor being of bifurcated form with two substantially parallel legs depending from a head portion, each of said legs beir?n profiled to define a series of axially spaced truncated forms with opposing sides which diverge away from the head portion.

8. An anchor according to Claim 7, wherein each leg extends over a substantial part of the length of the anchor.

9. An anchor according to Claim 7 or Claim 8, wherein the truncated forms of each leg are defined by a wave-like profile at each of two opposite sides of the leg, with the wave-like profile on one of said sides being axially offset relative to the wave-like profile on the other of said sides whereby to provide an out of phase relation between the profiles to define the truncated forms. 1' 0. An anchor according to Claim 9, wherein the anchor is cut from sheet material of constant thickness and the wave-like profiles on each leg are formed in the thickness dimension of the leg whereby each leg is of constant thickness and varying widths defined by the opposing wave-like profiles. F 11. An anchor according to Claim 10, wherein, for each leg, the axes of the two wave-like profiles are relatively inclined whereby the leg is of reducing width in a direction away from the head portion.

12. An anchozt according to Claim 11, wherein, for each leg, 93081 ,p:\oper\rshanciorsspe,14 %A utpr;n or embedment. I ii ii tht; axis of is parallel axis of the inclined to width. the wave-like profile at an outer side of the leg to the longitudinal axis of the anchor, and the opposing profile at an inner side of the leg is the longitudinal axis to provide the reducing

13. An anchor according to any one of Claims 9 to 12, wherein the wave-like profile at an outer side of the leg has crests and troughs each of which are symmetrical about an axis at right angles to the longitudinal axis of the profile.

14. An anchor according to any one of Claims 1 to 13, wherein the head portion has an eye for engagement by lifting means extending through the eye. An anchor according to any one of Claims 1 to 14, wherein said angle of inclination is between 10 and

16. An anchor according to any one of Claims 1 to 14, wherein said angle of inclination is substantially

17. An anchor according to any one of Claims 1 to 14, wherein at least one of the opposed sides of each truncated form is inclined to the longitudinal axis of the anchor at an angle of substantially

18. An anchor according to any one of Claims 1 to 17, wherein each truncated form ir solid in order to prevent collapse of the form.

19. A lifting anchor for incorporation within a concrete component during casting of the component to provide a lifting point for the component, said anchor comprising a head portion adapted to remain at least partly exposed for engagement by lifting means and a body portion for embedment within the concrete, said body portion being shaped to cause secure anchorage of the anchor within the concrete under the lifting .4 4 *44 44 4. B 1" 9308 12pAperrsbkancorsspc,15 tf-16- loads, said shape comprising a plurality of solid truncated forms having opposed sides which diverge in an axial direction away from the head portion, said truncated forms extending along at least a majority of the length of the body portion and having such a lateral extent that the or each truncated form constitutes the primary means for securing anchorage within the concrete; and said truncated forms being such that collapse of the form by deformation of the sides of the form during lifting is prevented, each truncated form being displaced axially from an adjacent truncated form, and the sides of the form being inclined to the longitudinal axis of the anchor at an angle of inclination of between 5 and A lifting anchor for incorporation within a concrete component during casting of the component to provide a lifting point for the component, said anchor comprising a head portion having an eye which remains exposed for engagement by lifting means extending through the eye, and a body portion for i embedment within the concrete, said body portion being shaped to cause secure anchorage of the anchor within the concrete j under the lifting loads wherein said head portion is of plate- like form with the eye being formed by an aperture extending through the plate-like head portion at right angles to the major surfaces of the head portion and the body portion being i' shaped to define a plurality of truncated forms having upwardly facing opposed sides which diverge in an axial :direction towards the base of the anchor, said divergent sides extending at least in the planes containing the major surfaces of the head portion, and the size and extent of the truncated forms being such that the forms provide substantial anchorage S'of the body portion within the concrete, and said truncated forms being such that collapse of the form by deformation of the sides of the form during lifting is prevented, each truncated form being displaced axially from an adjacent Struncated form, and the sides of the form being inclined to the longitudinal axis of the anchor at an angle of inclination of between 5 and 1 ,930813,p:\oper\rshanchomspe,16 i 17

21. A lifting anchor as claimed in claim 1, substantially as herein described with reference to any one of the drawings. DATED this 12th day of August, 1993 RANSET FASTENERS (AUST.) PTY.LIMITED By its Patent Attorneys: DAVIES COLLISON CAVE 93O8lZp:\oper\rshbanchors--sp,17 i' iij I, I 4 I 4S 4 4 445 4 4 4 4 4 4 4 I 44,4 'I 4 544449