EP0211256B1 - Anchor for embedding large loads in concrete - Google Patents

Abstract

An anchor of solid material is adapted to be embedded in a heavy load, for example, a precast concrete member, for permitting lifting of such member. The anchor is comprised of a head formed with a recess for receiving lifting apparatus, and a solid anchor shank terminating at its lower end in a foot adapted to be embedded in such precast member. A separately formed insert extends through an opening formed in the anchor shank, and is positively secured in the opening. The insert has expanding extensions which project laterally from the shank, with the extensions having flat saddle surfaces on the top thereof for better absorption of load forces applied to the anchor. In another embodiment, the separate insert part is positioned around the shank of the anchor and protrudes from all sides. The shank is formed with recesses, and the insert is deformed to be engaged in the recesses and to provide inclined saddle surface at the top of the insert.

Description

The invention relates to an anchor consisting of solid material for concreting into heavy loads, such as precast concrete elements, according to the preamble of patent claim 1.

For transporting heavy loads, in particular precast concrete parts, such as prefabricated multilayer panels, room cells, facade cladding, supports, parapet elements and the like The surface of the concrete part protrudes. The head of the anchor is usually in a recess provided in the precast concrete part, so that it does not protrude above the upper edge of the component. Transport anchors of this type are made of round steel or flat steel. The round steel anchors have a raised round head and a flange-like foot to absorb the forces that occur when lifting. Flat steel anchors have a recess in the head section for coupling the hoist. In the usual design for introducing the tensile forces into the concrete, the base part encased in concrete is provided with spreading lugs, which are formed by cutting the flat material in the base part and by bending apart the legs created by the cutting. The dimensioning of the cross section of this has long been However, known anchors depend on the size of the resistance moments that occur, because, depending on the load, there must always be a sufficient cross section of the anchor to prevent the spreading lugs from bending back under load and thus preventing the concrete-embedded anchor from being torn out. It is therefore necessary, when dimensioning such anchors provided with base-side spreading lugs, to adhere to a minimum cross-section, in particular a minimum thickness, which is predetermined for the load intended in each case, in order to counter the risk of the anchor being torn out.

Round anchors with a widened foot and flat anchors with expansion lugs must also be concreted into the precast concrete with a load-dependent minimum depth. The greater the load to be borne, the deeper the base of the anchor must be anchored in the concrete part. The installation depth of an anchor provided with base-side expansion lugs also depends on the approximately conical shape of the lines of force, which are determined by the saddle load and define the so-called breakout cone for the concrete of the precast element. This breakout cone should be as large as possible on the sides of the precast element to prevent the concrete from breaking out when the precast element is lifted. In addition, flat anchors with expansion lugs require a relatively large overall length, since the spreading of the foot caused by separating the flat material affects its strength, especially since the incision must be relatively deep in order to avoid excessive deformation of the legs when bending.

With flat anchors with expansion lugs and also with round anchors with round, widened feet, it is not possible to exactly measure the forces introduced into the precast concrete element via the anchor to be predetermined. This is particularly disadvantageous in the case of precast concrete parts of small thickness, because the breaking strength of such a precast part provided with concreted-in anchors cannot be precisely calculated.

For thin precast concrete elements, it is also known to use so-called two-hole anchors made of flat steel, which are intended to ensure that the load is introduced deeper into a thin precast concrete element (US Pat. No. 4,538,850). The head part of such two-hole anchors is designed like flat anchors. In the foot section there is a round or oval hole through which a so-called additional iron is threaded before concreting in. In order to be able to thread the additional iron quickly and easily before concreting in, the hole in the foot part of the two-hole anchor must have a correspondingly large amount of play. In addition, the additional iron must have a sufficient length, which can be ten times the anchor length, in order to achieve secure anchoring. These requirements result in a relatively high expenditure of material and costs, especially since the separate threading of the additional iron requires an additional, relatively laborious process.

The lifting anchor according to the preamble of claim 1 (US-A-4 580 378) consists of a flat iron with a recess provided in the anchor head for coupling the hoist and a round bolt which passes through a recess of the anchor base as an insert. The round bolt is intended to prevent the cast-in anchor from tearing out when the precast concrete element is lifted. Its ends therefore form laterally approaches protruding the cross section of the anchor, the partially cylindrical surfaces of which absorb load forces resulting from the tensile force when the precast concrete element is lifted. Because of the cylindrical shape of the lugs, the flat anchor can only absorb relatively small load forces, and these lugs have a wedge effect under the tensile force, which can lead to the anchor being torn out under high load and resulting in an outbreak cone which is unfavorable in terms of position and size.

A round anchor intended for transporting precast concrete parts is also known (FR-A-2 102 100), which essentially consists of a fully embedded, open-ended sleeve with an internal thread for receiving a lifting element and can be solidly formed on the closed sleeve end. This end is reduced in diameter at the bottom, so that a flat part with its correspondingly large bore can be pushed on there. The flat part then lies with its main plane perpendicular to the axis of the sleeve and is held at its massive lower end in that an annular, aligned with the reduced end portion of the sleeve end extension is expanded like a full rivet. The inserted flat part that completely surrounds the sleeve can absorb loads acting perpendicular to its main plane, which result from the tensile force, but the tensile force is only introduced into the flat part via the widened ring extension of the sleeve. The forces occurring at this connection point can easily lead to a deformation of the ring approach, which engages under the flat part only with a conical widening, so that the flat part can tilt and the anchor sleeve can be pulled out of the bore of the flat part unintentionally when loaded.

Based on the generic anchor (US-A-4 580 378), the invention has for its object to design the flat anchor so that the side approaches can accommodate saddle loads without risk of tearing for the anchor and according to material, size, shape and location with little technical The effort must be adapted to a given load case.

The object is achieved according to the invention with the characterizing features of claim 1.

In the case of the anchor according to the invention, the insert part which forms the lugs and is inserted into the recess of the anchor base is deformed in such a way that it is connected to the anchor base in a non-detachable manner and thus the risk of the anchor being torn out of the concrete is reliably prevented. The existing saddle surfaces for the concrete due to the flat design of the lugs can absorb large loads without the lugs being able to detach from the flat iron. These saddle surfaces can be designed to suit the respective load case and aligned with the flat iron, preferably in such a way that they are arranged symmetrically to the longitudinal median plane of the flat iron lying between them.

The manufacturing effort is low, since the anchor consists of only two simple parts, the flat iron, which forms the head, shaft and foot of the anchor, can be manufactured by punching and only a plug connection between the flat part and the plug-in part is necessary for assembly is then deformed.

Further features of the invention emerge from the subclaims.

Fig. 1

einen Spreizanker in bekannter Ausführung,

Fig. 2

einen Rundanker in bekannter Ausführung,

Fig. 3 bis Fig. 3b

einen erfindungsgemäßen Anker, dessen Kopf, Schaft und Fuß aus einem Flacheisen bestehen, wobei Fig. 3 eine Ansicht auf die Breitseite und Fig. 3a eine Ansicht auf die Schmalseite des Flacheisens und Fig. 3b eine Draufsicht auf den Anker darstellt,

Fig. 4

den unteren Teil eines abgewandelten erfindungsgemäß ausgebildeten Ankers mit einem Flacheisen in einer Ansicht entsprechend Fig. 3a,

Fig. 5

den Anker nach Fig. 3, einbetoniert in ein Betonfertigteil,

Fig. 6, 6a und 6b

eine andere Ausführungsform eines erfindungsgemäßen aus Flacheisen bestehenden Ankers in Ansicht auf die Breitseite (Fig. 6) und die Schmalseite (Fig. 6a) und in Draufsicht auf das Einsetzteil.

The invention is explained in more detail below with reference to the drawings. Show it

Fig. 1

a spreading anchor in a known design,

Fig. 2

a round anchor in known design,

3 to 3b

3 shows a view of the broad side and FIG. 3a shows a view of the narrow side of the flat iron, and FIG. 3b shows a top view of the anchor,

Fig. 4

the lower part of a modified anchor designed according to the invention with a flat iron in a view corresponding to FIG. 3a,

Fig. 5

3, concreted in a precast concrete part,

6, 6a and 6b

another embodiment of an anchor according to the invention consisting of flat iron in a view of the broad side (Fig. 6) and the narrow side (Fig. 6a) and in plan view of the insert.

1 shows a known flat iron anchor 1 made of solid material. The anchor has a head 3 with a recess 3 'for hanging the coupling part of a hoist, a shaft 4 and a foot 5. The foot 5 has lugs 7 in the form of spread legs, which are created by cutting the foot and bending the legs apart. In the installed position according to FIG. 1, the anchor base is concreted into a prefabricated concrete part 2 with the spread lugs 7; its surfaces facing the anchor head 3 form saddle surfaces 6. When the prefabricated concrete part 2 is raised by means of a lifting device acting on the anchor, the tensile forces act in a wedge shape in the concrete mass located above the saddle surfaces 6. This area is called the breakout cone.

Fig. 2 shows a well-known round anchor, which is embedded in a relatively thin precast concrete so that the anchor head 3 does not protrude beyond the upper edge 2 'of the precast. A round anchor foot 5 adjoins the concreted-in anchor shaft 4, which forms a round attachment 7, which projects beyond the cross section of the shaft and has a saddle surface 6. As a result of this design of the anchor foot 5, the fifth wheel load is distributed on all sides. When installed in relatively thin precast concrete elements, this has the disadvantage that the saddle forces enter the parallel surfaces 2a of the precast concrete element in a relatively short way. The lines drawn show the relatively large breakout cone that occurs here and directly covers the side walls of the precast concrete part.

Embodiments of the anchor according to the invention are shown in FIGS. 3 to 6.

3 to 3b show a flat iron anchor with anchor head 3 including receiving opening 3 'for the hoist, anchor shaft 4 and anchor base 5 concreted in precast concrete 2. The head, shaft and foot of the anchor consist of a flat iron. The anchor shaft 4 has, at a sufficient distance from its lower edge 10, a recess 8 lying transversely to its narrow sides in the form of a round hole which, like the recess 3 ', is punched out of the flat iron. Fig. 4 shows a similar embodiment. In the recess 8 a separate from the flat iron 1 insert T is arranged, which is formed from a round bolt. The insert T has over the cross section of the shaft 4 laterally projecting lugs 7 and 7 'or 7a and 7b, which with the anchor head 3 facing, flat, that is flat, saddle surfaces 6 and 6' or 6a and 6b after insertion of the round bolt are molded in a pressing process. The middle section of this insert part T formed from the round bolt is held immovably in the recess 8 due to the broad, leaf-like design of the saddle surfaces 6 and 6 'or 6a and 6b. For an absolutely rigid connection between the round bolt section and the base 5 of the anchor, a deformation of the lugs 7 and 7 'or 7a and 7b can be provided in such a way that on both sides of the recess 8 there is a compressed, bead-like widening 15 or 15 'is formed, which has the shape of an annular extension at least partially surrounding the recess 8.

As a result of this design, the projections 7 and 7 'or 7a and 7b which protrude on both sides of the anchor foot 5 can be provided with saddle surfaces 6 and 6' or 6a and 6b, which in their geometric shape and in their inclined position the longitudinal center plane AA of the flat iron can be optimally designed with regard to the acting saddle forces, such that the position and size of the saddle forces and thus also the position and size of the breakup cone can be predetermined.

Advantageously, the surfaces 9 and 9 'or 9a and 9b of the lugs opposite the saddle surfaces 6 and 6' or 6a and 6b, ie facing the lower edge 10 of the armature, can also be designed as flat, that is, flat surfaces.

Appropriately, as can be seen from the drawings, the saddle surfaces are arranged symmetrically to the longitudinal center plane A-A of the armature lying between them, in order to enable precisely defined, uniform stresses on both sides of the armature 1.

Due to the provided flat pressure of the protruding ends 7 and 7 'or 7a and 7b forming the ends of the round bolt inserted into the bore 8, precisely definable flat and sufficiently wide mounting surfaces 6, 6' and 6a, 6b are created, each can be manufactured according to size and shape according to the design of the anchor so that the saddle forces can also be predetermined, ie defined. In comparison to the known expansion anchor with bent expansion legs and in comparison to the known two-hole anchor with a round supplementary iron or bolt in cross section, the anchor according to the invention results in a widened, larger saddle surface and thus a considerably lower surface pressure. The transverse forces occurring in known anchors are avoided, which occur there by bending the spreading legs or by the run of the additional iron or bolt are conditional and cannot be calculated exactly according to size and position. In the case of the anchor according to the invention, the rigid, form-fitting connection between the flat iron and the round bolt used with transversely projecting saddle surfaces 7 and 7 'or 7a and 7b creates an absolutely stable anchoring which can be predetermined with regard to the forces which occur.

Due to the deformation of the bolt inserted into the foot part 5 of the armature 1 to form lugs 7 and 7 'or 7a and 7b with flat saddle surfaces, there is the further advantage that the cross section of the bolt used is unchanged in the area in which the greatest load is present is effective, namely right next to the reveal of the hole 8, so that at this point there is a maximum cross section and thus sufficient strength of the bolt with respect to the greatest transverse forces occurring at this point.

The saddle surfaces 6 and 6 'or 6a and 6b are each advantageously inclined at an obtuse angle ∝ with respect to the side surface of the anchor foot 5 parallel to the longitudinal center plane AA (FIGS. 3a and 4). As a result, the saddle forces acting as normal forces perpendicular to the saddle surface can be via a larger spatial area and thus distributed over a larger concrete mass, which has a favorable effect when lifting the precast concrete part, since the concrete is less stressable than tensile stress. The lugs 7 and 7 'or 7a and 7b can have in the section going through the longitudinal axis of the flat iron and perpendicular to the longitudinal center plane AA approximately the shape of a right-angled triangle or an approximate trapezoidal shape such that their cross section increases in the direction of the recess 8 and is largest near the recess.

In the embodiment shown in FIG. 4, the saddle surfaces 6a and 6b are each inclined to the side surface of the anchor foot 5 parallel to the longitudinal center plane A-A at an angle ∝ which is larger than in the embodiment according to FIG. 3a. In comparison to known expansion anchors with a smaller angle of inclination of the expansion lugs, the anchor according to the invention can thus be concreted into the precast concrete element with less rigidity and with less installation effort. 4, the anchor according to the invention can therefore have a particularly short overall length, which also results in a corresponding saving in material.

The design of the anchor according to the invention is particularly advantageous in the case of relatively narrow or thin precast concrete parts, since the mounting forces that occur can be directed in such a way that the lines of force, unlike in the case of, due to the definable position and shape of the mounting surfaces 6 and 6 'or 6a and 6b 2, run essentially near the longitudinal center plane AA of the anchor and are therefore predominantly in the middle of the narrow precast concrete part. As a result, the stress on the side walls of the precast concrete element shown in FIG. 2 is largely avoided.

In the embodiment shown in FIG. 4, in addition to the saddle surfaces 6a and 6b inclined at an angle ∝, the surfaces 9a and 9b of the projections 7a and 7b lying opposite them are inclined towards the side surfaces of the anchor foot 5 parallel to the longitudinal center plane AA, the planes of the surfaces 9a and 9b each form an angle ∝ 'with the longitudinal center plane AA or the side surfaces of the anchor foot 5, which is smaller compared to the angle ∝. This results in a favorable, approximately trapezoidal cross section of the lugs 7a and 7b with relatively strongly inclined saddle surfaces 6a and 6b. As a result, the anchor can have an overall shorter overall length than the embodiment according to FIG. 3a with the same load capacity. Conversely, with the same overall length corresponding to the larger angle of inclination ∝ of the saddle surfaces 6a and 6b, there is a higher load capacity and thus a functional increase in the installation depth of the armature.

In the illustration according to FIG. 5, an anchor 1 of the embodiment according to FIGS. 3 to 3b is installed in a relatively thin precast element 2. The head 3 of the anchor is recessed into a recess in the precast concrete element, such that its upper edge 2, 2 'lies above the anchor head. In the anchor foot 5 there is the recess 8, into which the round bolt is inserted symmetrically to the anchor foot, in such a way that the lugs 7 and 7 'projecting on both sides of the anchor 1 are of equal length with their saddle surfaces 6 and 6' (see FIG. 3a). The saddle surfaces 6 and 6 'have a precisely defined position in the prefabricated concrete part 2 and the saddle forces are due to the chosen large inclination of the saddle surfaces (angle ∝ in Fig. 3a) essentially in the area of the anchor, which means a correspondingly large opening cone in the central area of the precast concrete part is concentrated.

The inclination of the saddle surfaces 6 and 6 'or 6a and 6b starting from the recess 8 also has the consequence that the lugs 7 and 7' or 7a and 7b lying transversely to the anchor 1 are subjected to less bending stress in comparison to Approaches whose surface lines of the load-bearing surfaces run at right angles to the longitudinal center plane of the anchor, or in which the saddle surfaces are concave (cf. FIG. 2).

6, 6a and 6b show another embodiment of the flat anchor according to the invention. Instead of a central recess, there are two groove-like recesses 8 'and 8 "in the base 5 of this anchor, which lie opposite each other. One of two projections 7c and 7d, which are part of a deformed, originally square flat iron piece 11, are pressed into these recesses in a form-fitting manner. 6 and 6b), which forms the insert part T. The flat iron piece 11 has a recess 12 which corresponds to the cross-section of the anchor foot 5 before the deformation and is delimited on its longitudinal sides by two middle sections 13 and 13 'of the flat iron piece the insertion and deformation of material of the flat iron piece 11 projecting on all sides beyond the outer contour of the anchor foot 5 forms saddle surfaces 6c, 6d, 6e and 6f. Around the flat iron piece 11 in an absolutely form-fitting manner in the groove-shaped recesses 8 'and 8 "which are rectangular in the view according to FIG. to be fastened, the two opposite central sections 13 and 13 'deformed approximately V-shaped on the flat sides of the anchor base 5 in the direction of the lower edge 10' of the anchor 1. In order to achieve the same saddle forces on the opposite saddle surfaces, the vertex 14 of the deformed middle sections 13 and 13 'lies in the longitudinal center plane A-A of the armature 1 lying between the shoulders 7c and 7d.

The anchor according to FIGS. 6, 6a and 6b also has the advantage of a definable mounting surface. The saddle surfaces 6c and 6d can be inclined downward, as in the embodiment of FIGS. 3 to 3b. With the alignment shown in FIGS. 6 to 6b perpendicular to the longitudinal center plane of the anchor, it can be achieved that the saddle forces run essentially parallel to the long sides of the precast concrete element, which is particularly useful in the case of narrow components, because forces directed transversely to these long sides, which can cause the precast concrete to break out sideways are largely avoided.

Since the saddle surfaces 6c, 6d, 6e and 6f surround the cross section of the flat iron forming the head, shaft and foot of the flat anchor 1 on all sides, the position and size of the saddle surfaces can be precisely determined depending on the specified load.

The V-shaped deformation of the insert T in the direction of the lower edge 10 'of the armature in the region of the two opposite central sections 13 and 13' has the further advantage that the load force can be precisely specified in its direction.

The manufacture of the anchor according to the invention is simple and inexpensive because of the low material requirement and the simple processing. The recess 8 or the recesses 8 'and 8 "should be at a distance from the lower edge 10 or 10' of the anchor which is sufficient to absorb the tensile forces occurring here with sufficient certainty on the base part of the anchor.

Claims (14)

1. Anchor consisting of solid material to be embedded in concrete in heavy loads such as precast concrete pro-ducts, with a flat bar, which comprises an anchor head (3) with a recess (3') for the connection of a lifting appliance, a solid anchor shaft (4) and an anchor base (5) to be embedded in concrete, in which at least one recess (8; 8', 8'') is provided, in which an insert part (T) is inserted in a form-locking manner, whereof the ends form projections (7, 7'; 7a, 7b; 7c, 7d) projecting laterally beyond the anchor cross-section, with surfaces for the load forces to be received, characterised in that the projections (7, 7'; 7a, 7b; 7c, 7d) are held immovably in the recess (8; 8', 8'') of the anchor base (5) due to subsequent deformation of the insert part (T) located on the anchor base (5) and the projections are designed to be flat so that their surfaces form saddle surfaces (6, 6'; 6a, 6b; 6c, 6d) for the concrete.
2. Anchor according to Claim 1, characterised in that the saddle surfaces (6, 6'; 6a, 6b; 6c, 6d) are arranged symmetrically to the longitudinal central plane (A-A) of the anchor (1) located therebetween.
3. Anchor according to Claim 1 or 2, characterised in that the saddle surfaces (6, 6'; 6a, 6b) are inclined with respect to the longitudinal central plane (A-A) of the anchor (1) so that they are directed outwards from the flat bar at an obtuse angle (∝).
4. Anchor according to one of Claims 1 to 3, characterised in that the surfaces (9a, 9b) of the projections (7a, 7b) located opposite the saddle surfaces (6a, 6b) are inclined with respect to the longitudinal central plane (A-A) of the anchor (1) so that they lie in a plane, which with the longitudinal central plane (A-A) of the anchor (1) forms an obtuse angle (∝') which is open towards the saddle surface (6a, 6b).
5. Anchor according to Claims 3 and 4, characterised in that the obtuse angle (∝) formed by the saddle surfaces (6a, 6b) with the flat bar is greater than the obtuse angle (∝'), which the planes of the opposing surfaces (9a, 9b) form with the longitudinal central plane (A-A) of the anchor (1).
6. Anchor according to one of Claims 1 to 5, characterised in that the surfaces (9, 9'; 9a, 9b; 9c, 9d) of the projections (7, 7'; 7a, 7b; 7c, 7d) lying opposite the saddle surfaces (6, 6'; 6a, 6b; 6c, 6d) are plane surfaces.
7. Anchor according to one of Claims 3 to 6, characterised in that in a section containing the longitudinal axis of the anchor shaft (4), the projections (7, 7') have approximately the shape of a right-angled triangle or a trapezium.
8. Anchor according to one of Claims 1 to 7, characterised in that the insert part (T) is a round bolt, whereof the ends projecting beyond the anchor cross-section are deformed to form the plane saddle surfaces (6, 6'; 6a, 6b).
9. Anchor according to Claim 8, characterised in that on both sides of the recess (8, 8') in the anchor base (5), the ends of the round bolt have an upset, bead-like enlargement (15, 15').
10. Anchor according to one of Claims 1 to 9, characterised in that the saddle surfaces (6, 6'; 6a, 6b) are widened towards the outside from the anchor base (5) and are preferably constructed in the form of blades.
11. Anchor according to one of Claims 1 to 7, characterised in that two recesses (8', 8'') are provided for receiving the insert part (T) in the anchor base (5), which recesses are formed by groove-like incisions in the opposite sides of the flat bar, and that the insert part (T) is a piece of flat bar (11), which is pressed by deformation into the recesses (8', 8'').
12. Anchor according to Claim 11, characterised in that the piece of flat bar (11) comprises a recess (12), which before deformation corresponds to the cross-section of the anchor base (5), and that after the insertion and deformation of the piece of flat bar (11), its parts projecting beyond the outer contour of the anchor base (5) form the projections (7c and 7d) with the lateral saddle surfaces (6c, 6d) and moreover further saddle surfaces (6e, 6f), which lie on both sides of the other flat sides of the anchor base (5).
13. Anchor according to Claim 12, characterised in that the central sections (13, 13') of the piece of flat bar (11), which define the longitudinal sides of its recess (12), are deformed in a V-shape for the form-locking mounting of the piece of flat bar (11) in the direction of the lower edge (10') of the anchor (1) defining the anchor base (5).
14. Anchor according to Claim 13, characterised in that the apex (14) of the V-shaped deformed sections (13, 13') of the piece of flat bar (11) lies in the longitudinal central plane (A-A) of the anchor located between the projections (7c and 7d).

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