AU665671B2 - Anchorage for reinforced concrete - Google Patents

Description

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OPI DATE 12/04/94 APPLN. ID 48240/93 AOJP DATE 07/07/94 PCT NUMBER PCT/FR93/00934 lIU iliiioIn nnui i AU9348240 DEN

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(51) Classification internationale des brevets.O (11) NUiro de publication iternationale: WVO 94/06983 E04G 21/14 Al (43) Date de publication internationale: 31 mars 1994 (3 1.03.94) (21) Numiro de la demnande internationale: PCT/FR93/00934 (74) Mandataire: VIARD, Jean; Cabinet Viard, 28 bis, avenue Mozart, F-75016 Paris (FR).

(22) Date de dip6t international: 24 septembre 1993 (24.09.93) (81) Etats d6signes: AU, BG, CA, JP, KR, PL, US, brevet euro- Doni;Aes relatives i~ la priorit6: p~en (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, 92/11380 24 septembre 1992 (24.09.92) FR LU, MC, NL, PT, SE).

93/03291 23 mars 1993 (23.03.93) FR Publi&e (71)(72) Deposant et inventeur: ARTEON, Marcel [FR/FR]; 16, Ai'ec rapport de rechzerchie internationale.

rue Cino-del-Duca, F-92200 Neuilly-sur-Seine A vant l'expiration du dMai pr~lu pour la mnodification des rei'endications, sera republik' si de telk's modifications sont (72) Inventeur; et repies.

Inventeur/D~posant (US seulemnent) :JOANNET, Lucien [FR/FR]; 37, rue de Portzmorguer, Le Cour~gant, F- 56270 Ploemeur (FR).

(54) Title: ANCHORAGE FOR REINFORCED CONCRETE (54)Titre: ANCRAGE POUR BETON ARME K-77 (57) Abstract Anchorage and anchor for concrete elements such as thin panels and pipes. The anchorage comprises an anchor having a split lower portion which can be fixed to a reinforcing bar and means for attaching the anchor to at least one reinforcing bar. Anchor points can thus be suitably positioned in a thin concrete element.

(57) Abregi Ancrage et ancre pour 616ments en b~ton tels que panneaux minces et tuyaux. L'ancrage comprend une ancre dont la partie inf~rieure est fendue pour pouvoir s'assujettir sur une armature et des moyens de liaison entre Ilancre et au momns une armature. 11 permet un positionnement appropri6 des points d'ancrage dans un 616ment mince en b~ton.

r V C, I-: 1 ANCHORING ;1Ee FOR REINFORCED CONCRETE The present invention provides an anchoring 4 piee intended particularly, but not exclusively, for reinforced concrete panels or pipes, Conventional anchoring devices having extraction cones are not suitable for handling thin pre-fabricated panels. The extraction cone cannot withstand the forces generated when the panel is lifted. It is therefore necessary to attach the anchoring device to the reinforcing irons which are included in the mold before the concrete is cast.

A first aim of the invention is to propose new ways of securing any type of anchoring device: those having an extraction cone, those that operate by adhesion, those having an eye, etc. and to allow an anchoring device to be positioned at any appropriate location in a thin concrete panel, wherever the reinforcing bars may be in that panel.

Moreover, it is known to use reinforced concrete pipes for large conduits, and some of these may be cast with internal reinforcing bars which are longitudinal and circular or helical, these being welded and uniformly distributed around the wall of the pipe. In order to handle such large-diameter pipes, it is desirable to use anchoring pieces which allow the pipes to be lifted and transported using gear such as cranes. Such anchoring pieces, which are used when the pipes are laid, avoid the use of clamps or handling slings which can spoil the outside surface of the pipes. In particular, so-called "eye" anchoring devices, in which reinforcing bar passes through an orifice, are difficult to use.

A second aim of the invention is to alleviate this problem.

A further problem posed by concrete is that of its porosity. It is known that concrete is not naturally liquid-tight, so that pressurized liquid may seep out, Sgiving rise to the traces of reinforcement rust which may 0 i i, I L 1

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iii: I 2 be seen on some structures. In time, the liquids may reach the anchoring piece and cause it to oxidize. This porosity results in particular from cracks which arise while the concrete is drying, due to the internal tensions developed. Unfortunately, it is necessary for pipes that are intended to convey possibly dangerous liquids to be liquid-tight. To this end, it is known to line the inside of the pipe, but such linings degrade with time and the concrete alone must provide the sealing.

A third aim of the invention is to avoid the formation of cracks.

According to the present invention, an anchoring device for reinforced concrete, the device comprisinc, an anchoring head having means for connection to lifting gear and also comprising a shank, is characterized in that it is terminated at its bottom end by a body which is split longitudinally, followed by a foot of transverse size greater than that of the shank.

Thus, the anchoring device in accordance with the invention may readily be positioned to straddle a reinforcing bar and, after casting, the device has the characteristics of a cone-type anchoring device due to the size of its foot in the direction parallel to the surface. The anchoring device is secured to the reinforcing bar which it straddles or to adjacent reinforcing bars by one or more ties or springs or clips.

According to another feature of the present invention, the anchoring device for reinforced concrete and comprising an anchoring head having means for connection to lifting gear, a shank and a body which is split longitudinally, terminating in a foot which protrudes from the bottom end of the shank, is characterized in that the body has at least one protruding lateral lug which is shaped to match grooves P for connection to the reinforcing bars.

r, i_ ,1 3 In the case where the anchoring device is to rest on a reinforcing bar, the width of the split is substantially equal to the diameter of the reinforcing bars. The anchoring device may, however, be positioned between the reinforcing bars or there may be no reinforcing bars at all. The head of the anchoring device may be of any type, provided that it can be gripped by lifting gear. It may be a cylindrical head, a threaded bush or shank, or simply a hole in a flat shank.

According to yet another feature of the invention, a supporting spring is mounted between the base of the anchoring device and at least one reinforcing bar.

Thus, the anchoring device is positioned over a longitudinal reinforcing bar, for example, and is held there whilst the concrete is being cast by the action of the spring which is compressed between the foot cr the body of the anchoring device, and one or more adjacent circular reinforcing bars.

According to another feature of the invention, in I 20 the case where it is being used in pipes, a perforated screen is interposed between the inside of the pipe and :I the anchoring device. The screen is connected to said supporting spring and at least partially surrounds the |foot of the anchoring device.

It has been observed that, due to the cracks which are produced while the concrete is drying, the concretemetal interface forms a path along which liquid seeps, causing the metal parts, particularly the reinforcing bars, to oxidize. The present invention is based on the idea that introducing a screen prevents the liquid from I passing in a radial direction from the inside to the outside of the pipe, at the reinforcing bars, by transforming the cracks into micro-cracks.

Preferably, this screen is constituted by a steel wire mesh constituting a fine mesh grating, or by a sheet pierced with holes of diameter substantially equal to the /i grain size of the concrete. Thus, a zone of liquid-tight

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4 micro-cracks is produced which prevents the formation of cracks which are not liquid-tight.

According to yet another variant of the invention, the anchoring device may be mounted, not tn the reinforcing bars, but on a spacer which rests on the bottom of the shuttering, while the pipe is being cast.

The anchoring therefore does not depend on the presence of reinforcing bars.

Other features and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given purely by way of non-limiting example, and with reference to the accompanying drawings in which: Figure 1 is an elevation view of an anchoring device of the invention; Figure 2 shows the same anchoring device in position on a reinforcing bar; Figure 3 is an elevation view of an anchoring device with lugs of the invention; Figure 4 shows the same anchoring device from above, in section on line IV-IV of Figure 3; Figure 5 shows an anchoring device of the invention mounted on a reinforcing bar; Figure 6 shows the same mounting as Figure viewed from the side; Figure 7 is a view from above; Figure 8 shows a first variant of the mounting; and Figures 9 and 10 show the mounting of reinforcing 30 bars on the anchoring device, viewed from the front and from above respectively.

In Figure 1, it can be seen that, in its plane of symmetry, the anchoring device comprises a substantially cylindrical head 1 which can be gripped by lifting gear (not shown), by means of a suitable fitting. A cylindrical shank 2 extends below the head 1, the length of the shank varying as a function of the anchoring to be V A pp.

r1 achieved, the shank being followed by a body 3 which, according to a feature of the invention, has a split 9 which is intended to span a reinforcing bar which is received in said split. The body 3 terminates in a foot 4, !:he d.idwuILer of whiLcri i3 greater then thoce f.f Lhe hoad and of the shink, the foot being intended to form an anchor-ing cone whien a force Is excorted on the anchor'ing device.

1rigure 2 shows the came anchoring device positined inside a m[u.L1 rt.rc c*-est:ing concrete (not shown). Ac previously indicated, the anchoring device J. straQ2~es the longitudinal reinforcing bar However, it may possibly pivot during casting, which impairs the quality of the anchoring device. To prevent such rocking, a spring 12 is disposed between the foot 4 and the circular reinforcing bars To avoid the anchoring device 1 being corroded by the liquids which may seep through the concrete, a screen 13 is advantageously provided below 'ceanchoring device, this screen surrounding the foot of the anchoring device in the example shown and being connected by its edges 14 to the points of contact between the spring 12 and the circular reinforcing bars A. Of course, any other securing means may be used,. The screen is constituted by a mesh, of a size through which the liquid concrete can pass, i.e. the screen is matched to the grain size of the aggregate which is mixed with cement and with very fine sand. in the example shown, the screen 13 is flat, but it may take some other form and enclose the anchoring device to a greater or lesser 30 extent. Moreover, the anchoring device may be protected from the outside moisture by a pre-fabricated cap of cement glued into the space around the head (not shown).

The spring 12 is mounted in compression between the upper surface of the foot 4 and two adjacent circular reinforcing bars A disposed on either side of the anchoring device. The spring bears against the surface 4 and also against the lower faces of the reinforcing bars

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6 A. Due to its elasticity, it therefore exerts permanent pressare on the asurfoc'c 4 which nlcmp~ thn anchor-in device vertical, opposing any vertical or lateral forces.

The spring 12 is constituted by two loupY furmitd r om a S single resilient wire. The two ends of this wire are free, so they can easily be mounted on the foot of the anchoring device. As previously indicated, the anchoring device may be positioned on a longitudinal reinforcing bar and function as the extractiuon coUl. Huowver, it is possible to mount such an anchoring device either between the reinforcing bars and without touching them, or in the absence of reinforcing bars, the anchoring device also being able to function by adhering to the concrete, in which case a spacer is mounted in the bottom of the formwork.

A second embodiment of the anchoring device can be seen in its plane of symmetry in Figure 3. In accordance with a feature of the invention, two lugs 5 protrude from the body 3 and are formed on their top or bottom surfaces i 20 with grooves 6 which allow the anchoring device to be secured either on an iron or below another iron.

Figure 4 is a section view along the line IV-IV of I Figure 3. This shows that the foot 4 protrudes beyond the body 3 to create a large extraction cone, the shape -1 and the surface area of the anchoring device determining the volume of the rupture or extraction cone.

Figures 5 to 7 show front, side and top views of an 0° anchoring device according to the invention, positioned Son a reinforcing bar B and connected to two reinforcing bars which are perpendicular to the reinforcing bar B.

The anchoring device straddles the reinforcing bar B which is inserted in the split 9. However, this mounting does not have the stability which is required for satisfactory support whilst the concrete is being cast.

In addition, the anchoring device is connected to the reinforcing bars A by steel wires F operating in tension- S compression, the diameter of which may for example lie in

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r 1~-.11 O- ~IX(IQ1~~ 7 the range 2.5 mm to 3.5 mm, the reinforcing bars A and B very often constituting a lattice (if not, they must be bound together). By their adherence to the concrete, the positioning wires F assist in increasing the anchoring capability at the instant of lifting. The wires F eliminate the need for guide bars or supports bearing ayalitL tlhe edges of the ahuttering, ond oupporting or suspending the anchoring device, thereby providing a saving of investment and oignifioantly reducing the handling time before each casting operation and of subsequent withdrawal from the mold.

Figure 7 shows a view from above of a first possible mounting method corresponding to theexample of Figure 3.

Two wires F are lodged in the grooves 6 of the lugs and pass underneath two parallel reinforcing bars A. In this case, the anchoring device is supported by the reinforcing bar B via the wires F which are lodged in the grooves 6 and underneath the reinforcing bars A. As shown by a dotted line, a single wire Fl may be used on its own, the wire being bent into the shape of a hair-pin and being connected at both of its ends to a single reinforcing bar A. The tension force on the wires holds the anchoring device in position.

Figure 8 shows from above another variant. In this case, the hair-pin is positioned between two parallel reinforcing bars Al and A2. The wire F passes underneath the lugs 5, underneath the reinforcing bar Al and over the reinforcing bar A2. It is bound onto the reinforcing bars A at 8 and onto the lugs 5 at 18.

30 As previously indicated, the anchoring device may be positioned on a longitudinal reinforcing bar and function as an extraction cone. It is however possible to mount such an anchoring device, either between the reinforcing bars and with no contact between these and anchoring device, or in the absence of reinforcing bars, the anchoring device also being able to function directly with reinforcing bars which adhere to the concrete.

1, i-fi 4 n 1 I 8 The lugs 5 which are provided for securing the anchoring device may also serve to position reinforcing irons by using the principle of anchoring by adhesion if the anchoring capability is to be increased.

Figures 9 and 10 show schematically an anchoring device according to the invention with complementary reinforcing bars C which use only adherence to the concrete.

Lugs 5 such as those which have just been described may be used with any type of anchoring device. In this case, they are advantageously mounted on a suitablyshaped part which may be secured to the anchoring device.

Of course, numerous variations can be made, particularly by substituting equivalent technical means, without departing from the ambit of the invention.

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Claims (3)

1. 2. An anchoring device for reinforced concrete, according to claim 1, Ii characterized in that the body has at least one protruding lug which is shaped to provide grooves of semi-circular cross-section which may receive wires for connection to the reinforcing bars.
2. 3. An anchoring device for reinforced concrete, according to either of claims 1 or 2. characterized in that a support spring is mounted between the of the anchoring device and at least one reinforcing bar. {j 4. An anchoring device according to any one of claims 1 to 3, characterized in that a perforated screen is interposed between the bottom ji 20 end of the anchoring device and the wall of the concrete opposite the anchoring device. An anchoring device according to claim 4. characterized in that the !I screen is connected to the spring, the spring at least partially surrounding S't the foot of the anchoring device.
3. 6. An anchoring device substantially as hereinbefore described with reference to the accompanying drawings. DATED this 20th day of October 1995 I MARCEL ARTEON Patent Attorneys for the Applicant: F.B. RICE CO, \O 0 N n n ABSTRACT An anchoring device and an anchor for concrete elements such as pipes and thin panels. The anchoring device comprises an anchor whose bottom portion is split to enable it to be applied to a reinforcing bar (B) and means for connection between the anchor and at least one reinforcing bar. The anchoring device makes it possible to position anchoring points appropriately in a thin concrete element. t* S i