EP0947640B1 - Reinforcement with high adherence - Google Patents

Abstract

The anchoring portions (2) at intervals at its ends have protruding radial portions, the ratio between their external diameter and the core diameter being greater than is the case with a screw thread. Typically this ratio can be between 1.3:1 and 2:1, and the size of the faces can decrease in inverse proportion to the number of the anchoring portions. The sum of the surface areas of (11) the portions can be at least five times the cross-sectional area of the core.

Description

The invention relates to a device for concentrated introduction of force in concrete with at least one existing steel, rod-shaped reinforcing element, which is provided with anchoring elements, the circumferential, over the core cross-section of the rod-shaped reinforcing element radially projecting, have a composite with the concrete producing application surfaces.

An arrangement of this type is known from US 2 137 718 A. In this known arrangement, the rod-shaped reinforcing element is provided for forming the anchoring elements with a circumferentially arranged, fixed by welding wire helix, wherein the length of the welded wire helix is limited to a portion of the length of the rod-shaped reinforcing element. The formation of the anchoring elements as a welded wire helix requires a high production cost. In addition, the welding process due to the resulting heat to I okale structural changes within the core material and / or lead the material of the wire helix, which can lead to an increased risk of breakage.

The US 5,449,563 A shows a rod-shaped reinforcing element, which is provided with a circumferentially mounted, welded or soldered helix. This should consist of zinc. The goal here is not a better bond but a corrosion protection of the reinforcing element on a galvanic basis.

The US 5 038 545 A shows a rod-shaped reinforcing element with circumferentially welded ribs. Here, ribbed areas alternate with ribless areas along the length. The aim of this known arrangement is namely to be able to easily bend the rod-shaped reinforcement element. For this purpose, ribless areas are provided. To achieve a good bond with the concrete ribs are provided in subsequent areas.

However, these are always either clamped or welded in a separate operation.

The CH 364 886 C shows a reinforcing rod, which is provided in the region of one end with a rolled thread on which an anchoring body is screwed in the form of a nut. The force is introduced into the concrete via the nut, which produces the composite with the concrete. The thread is used to make a screw the nut with the rod and not for the production of a composite with the concrete. The thread therefore represents a screw thread here.

The standard solution used today for reinforcing the concrete with regard to the absorption of tensile or compressive stresses consists of ribbed reinforcing bars. The bonding of these bars to the concrete is mainly ensured by ribs or notches whose profile heights reach less than 10% of the bar diameter. However, this bond is comparatively weak: If tensile stresses reach the concrete tensile strength in the area of such bars and the reinforcing bar assumes the corresponding tensile force after the resulting crack, the bond between reinforcement and concrete is destroyed to a certain length next to the banks of cracks. The expansions of the rebar add up to more or less large crack widths. In certain cases, such as B. transverse tensile stresses due to large compressive forces, thereby the capacity of the reinforced concrete construction is significantly limited.

The most common type of training of tensile or compressive force anchorages in steel and prestressed concrete structures consists in the arrangement of the so-called anchoring lengths for ribbed reinforcing bars, which are to be formed according to DIN 1045 or ENV DIN 1992-1. These anchoring lengths have the disadvantage that relatively long lengths are required for the introduction of the forces, in particular for straight bars due to the comparatively weak composite. They are about forty times the bar diameter for the ribbed bars in the most common concrete.

Shorter anchoring lengths can be achieved by using conventional threaded rods for anchoring. From the application as composite dowels It is known that the anchoring length in this training must be about ten times as long as the rod diameter.

In the event that the lengths required for such anchors are not available or should be greatly shortened for any reason, either anchor plates are arranged in practice as a special solution, which are welded at the rod end perpendicular to the rod axis or disc-shaped head thickening formed. The latter are u. a. known from EP 0495 334 B1 and DE 195 48 685 C1.

Due to the strength differences between the anchors and the concrete, the protrusion overhangs in these cases must be about eight to ten times larger than the anchor cross section. As a result, the applicability of this solution but u. a. severely limited, if anchoring bars arranged only a few centimeters away from the concrete surface do not provide sufficient space for anchor plates or if the anchor heads are to be installed in an already existing reinforcement net.

On this basis, it is therefore the object of the present invention to develop reinforcements or anchoring elements, which ensure a high-strength bond and thus require for the virtually slip-free power transmission both the shortest possible length and take in relation to the core cross-section as small as possible gross cross-sectional area.

This object is achieved in that the reinforcing element is formed as a section of a prefabricated rod and is provided over the entire length with molded anchoring elements, wherein the ratio of the outer diameter of the anchoring elements to the diameter of the circular core cross section between 1, 3 and 2.

The object according to the invention can advantageously be produced in the form of a long bar, from which in each case reinforcing elements of the desired length can be cut off. The measures according to the invention therefore enable a simple and inexpensive production and logistics.

The integrally formed anchoring elements can be designed as annular and / or disc-shaped and / or spiral-shaped and / or complementary to such forms elements. In any case, the diameter ratio according to the invention leads advantageously to a significantly greater depth of the application surfaces, as is the case with normal screw threads. The measures according to the invention therefore also bring a very considerable advantage for the carrying behavior. Over the entire length provided anchoring elements lead along the entire length of the associated reinforcing element to a high-strength bond between this and the surrounding concrete. As a result, on the one hand virtually slip-free load discharges can be achieved. On the other hand, only very small crack widths can develop in concrete after exceeding the concrete tensile strength at right angles to the reinforcing element, which is advantageous both for the durability and for the load-bearing capacity of the overall construction. The very good bonding behavior in conjunction with the thus ensured small crack widths continue to form the basis for the reinforcement of the invention readily with significantly higher strengths than the usual today reinforcing steel can be performed, which advantageously to very small gross cross-sections and thus very good Installation conditions and low costs leads. Due to the ratio of the invention between the diameter of the core cross-section and the outer diameter of the anchoring elements of steel lower compressive strength of concrete is still taken into account, so that no overuse of the concrete is to be feared.

Advantageous embodiments and expedient developments of the higher-level measures are specified in the subclaims. Thus, the ratio of the outer diameter of the anchoring elements to the diameter of the core cross section can advantageously be 1.4 to 1.5, which is particularly favorable both in terms of production and in terms of power transmission.

Another expedient measure may be that the anchoring elements are distributed uniformly over the length of the reinforcing element. The anchoring elements can here be advantageously dimensioned the same way over the entire length. In cases with uneven distribution of the anchoring elements The size of the application surfaces with the number of anchoring elements per unit length can decrease inversely proportional and vice versa.

Particularly good results have been achieved if four to five anchoring elements are provided on a length corresponding to twice the core diameter.

Further advantageous embodiments and expedient developments of the parent measures are specified in the remaining subclaims and from the following description of the example with reference to the drawing closer.

Figur 1

eine Seitenansicht eines stabförmigen Bewehrungselements mit auf der ganzen Länge durchgehend ohne Zwischenabstand vorgesehenen, ringförmigen Verankerungselementen,

Figur 2

eine Seitenansicht eines stabförmigen Bewehrungselements mit auf der ganzen Länge durchgehend ohne Zwischenabstand vorgesehenen, spiralförmigen Verankerungselementen,

Figur 3

eine Seitenansicht eines stabförmigen Bewehrungselements mit auf der ganzen Länge durchgehend mit gegenseitigem Abstand vorgesehenen, spiralförmigen Verankerungselementen,

Figur 4

eine Seitenansicht von Bewehrungselementen, die zu einer Schubbewehrungseinheit zusammengefügt sind und

Figur 5

eine Draufsicht auf die Anordnung gemäß Figur 4.

In the drawing described below:

FIG. 1

a side view of a rod-shaped reinforcing element with provided throughout the entire length without intermediate spacing, annular anchoring elements,

FIG. 2

a side view of a rod-shaped reinforcing element with provided throughout the entire length without intermediate spacing, helical anchoring elements,

FIG. 3

a side view of a rod-shaped reinforcing element with full-length continuously provided at a mutual distance, helical anchoring elements,

FIG. 4

a side view of reinforcing elements, which are assembled into a shear reinforcement unit and

FIG. 5

a plan view of the arrangement of Figure 4.

The subsequently applied spiral anchoring elements (13, 13 a, 13 b) do not belong to the subject matter of claim 1.

FIGS. 1 to 3 show different variants of the reinforcement according to the invention. From the basic forms shown here, each consisting of a supporting core cross-section 1 and several, lastaufnehmenden bzw.- donating to The core cross-section 1 integrally formed anchoring elements 3 and 4 or 5, any number of other forms can be developed.

In Figure 1, the anchoring elements 3 are disc-shaped or annular. The reinforcing bar shown is continuous, that is provided on its entire length with reinforcing elements 3. These can be arranged with or without intermediate spacing. In the example shown, no intermediate space is provided. Characterized in that the reinforcing rod is continuous, that is provided over its entire length, with reinforcing elements 3, results in a simple production and logistics. It is not necessary to produce such reinforcing bars in the dimensions of the individual application. Rather, long bars can be produced, from which the reinforcing bars can be easily cut to length for the individual application.

The reinforcing bar shown in Figure 2 differs from the previous one in that the continuous, that is provided over the entire length of the reinforcing bar anchoring elements form a continuous here, that is not interrupted spiral. But even with mutually spaced spiral sections would be conceivable. The slope of the spiral is here so that the turns connect directly to each other. For the load capacity, the difference with respect to annular anchoring elements is negligible. However, the production is relatively simple, since the spiral anchoring elements can be produced by rollers or rollers comparatively inexpensive. In the non-cutting production by rolling or rolling arise in any case due to the deformation hardening higher strength of the reinforcement than in spanender production.

Notwithstanding the illustration in Figure 2, the cross-sectional shape of the anchoring elements 4 may be formed instead of the drawn flat boundary surfaces preferably with rounded grooves. In addition to the further simplified production, this also leads to an increase in the fatigue strength of the finished reinforcement.

In the embodiments according to Figures 1 and 2, the anchoring elements 3, 4, as already mentioned, without mutual spacing over the length of assigned reinforcing rod provided throughout. But it would also be an arrangement of the reinforcing elements 3, 4 conceivable with spacing.

In the arrangement according to FIG. 3, a reinforcing element 5 designed in the manner of a cylindrical screw, which is often customary in mechanical engineering, is provided. Again, that the reinforcing element 5 forming screw need not necessarily be limited sharp-edged, but rather by the rounding of the screw cross section, the advantages already mentioned above can be achieved. As a result of the comparatively larger pitch of the screw underlying FIG. 3 in relation to the spiral on which FIG. 2 is based, in the case of the arrangement according to FIG. 3 intermediate distances occur between the individual screw turns.

Due to the low material cost and in particular the lower deformation energy expenditure, the embodiment according to FIG. 3 can be produced even more cost-effectively than the arrangement according to FIG. The difference in bearing capacity is likely to be negligible in most applications.

A particularly advantageous application provides the reinforcement with high-strength composite in securing flat slabs against punching. Such an example is based on FIGS. 4, 5. The failure of flat slabs in the area of the supports described with the descriptive term "punching" can be interpreted as a slit fracture as a result of very large, biaxial, inclined compressive stresses. So far, usual reinforcements such. B. anchors with disc-like head thickening are not able to effectively limit the resulting due to the biaxial compressive stresses transverse strains due to their limited composite effect. The existing shear reinforcement thus can not prevent the failure of the frusto-conical pressure surface. It only hangs the bearing loads of the flat ceiling after the failure of the pressure surface in the upper, over the fracture surface (15) remaining part of the ceiling. This system change due to the pressure fracture affects the bending resistance of the flat very disadvantageous, which has not yet been researched in detail.

If, however, according to FIGS. 4 and 5, reinforcements with permanently existing high-strength composite are installed for thrust protection, the damaging transverse strains are prevented and the frustoconical pressure surface can absorb considerably higher loads.

4 shows a fragmentary cross section through a flat ceiling 10 in the region of a support 11. The shear reinforcement consists of reinforcements 12 a - c with anchoring elements 13. The anchoring elements are formed according to the invention. Welded or clamped anchoring elements are not according to the invention. The reinforcements 12a-c are grouped together with a carrier 14 to form a shear reinforcement unit, whereby they can be installed particularly easily and with reliable securing of the required position. In comparison to the known systems with comparatively large-area end anchors, the incorporation of the anchors according to the invention between a network of bending reinforcement as a result of the substantially smaller gross cross-sectional area is considerably simpler and thus less expensive. On the displaceable connection of the armature 12 a - c with the carrier 14 will be able to dispense with this simplification in numerous applications, whereby the cost can be made even cheaper.

FIG. 5 shows the group-wise arrangement of the shear reinforcement unit according to FIG. 4 in plan view. Here, by way of example, the armatures 12 a and 12 b, for example, by welded joints 16 fixedly connected to the carrier 14, while the armature 12 c can be moved by means of a suitable connecting element 17 within the support opening 18, if necessary, to the previously laid To be able to dodge the reinforcement 19.

One of many other applications can be the formation of push bars, as they are required in most sheared steel and prestressed concrete components, which are designed here with the help of extremely space-saving anchors according to the invention as open bracket. This is always advantageous if the usual closed bracket would complicate the installation of the rest of the reinforcement.

Another possible application may be the formation of joint carriers, by means of which those of e.g. by a Dämmfuge distanced from a subsequent reinforced concrete slab cantilever bearing forces and the Biegezug- and -druckkräfte be passed over the Dämmfuge.

In this case, both the bending tensile forces occurring above and the bending pressure forces which become effective below are extremely advantageously absorbed by anchor rods according to the invention, which are equipped with uniformly distributed anchoring elements, guided via the insulating joint and introduced there again.

As a result, the joint carriers can be made extremely short in comparison to all previously available on the market systems, without additional welds or precise connections with the reinforced concrete reinforcement are required. There are quite significant advantages for the production, logistics and installation of such support elements.

Due to the small gross cross-section of the anchor elements they can be arranged relatively close to the upper or lower concrete surface and thereby additionally give a favorable structural behavior, because the lever arm of the internal forces compared to the previously known systems is significantly larger.

A variety of other advantageous applications always results where forces must be introduced from the concrete to very short lengths in the anchor elements such. B. arranged on the concrete surface anchor plates on the external loads -. As of crane runway girders, suspended canopy structures, steel columns, warehouse structures or otherwise - be initiated.

Numerous other advantageous applications are conceivable, such. As in the reinforcement of consoles and the formation of reinforced concrete composite structures. The anchoring elements according to the invention can be supplemented for further applications by various types of sleeves.

Claims (12)

1. A device for the concentrated force transmission into concrete comprising at least one bar-type reinforcing element consisting of steel which is provided with anchoring elements (3 - 5, 13) having circumferential application surfaces radially projecting from the core cross-section (1) of the bar-type reinforcing element and forming an adhesion with the concrete, characterised in that the reinforcing element is designed as a section of a prefabricated rod and provided along its entire length with anchoring elements (3 - 5, 13) formed integral therewith, with the ratio of the external diameter of the anchoring elements (3 - 5, 13) to the diameter of the circular core cross-section (1) being between 1.3 and 2.
2. A device according to Claim 1, characterised in that the ratio of the external diameter of the anchoring elements (3 - 5, 13) to the diameter of the core cross-section (1) is 1.4 to 1.5.
3. A device according to any of the preceding claims, characterised in that the size of the application surfaces decreases in inverse proportion to the number of anchoring elements (3 - 5, 13) per unit length.
4. A device according to any of the preceding claims, characterised in that the mutual distance between the anchoring elements (3 - 5, 13) measured at the outer edge thereof corresponds at least to the projection of the anchoring elements from the core cross-section (1) of the associated reinforcing element.
5. A device according to any of the preceding claims, characterised in that the mutual distance of adjacent anchoring elements (3 - 5, 13) measured at the outer edge thereof maximally corresponds to ten times their projection from the core cross-section (1) of the associated reinforcing element.
6. A device according to any of the preceding claims 4 or 5, characterised in that four to five anchoring elements (3 - 5, 13) are provided on a length corresponding to double the core diameter.
7. A device according to any of the preceding claims, characterised in that the anchoring elements (3 - 5, 13) are evenly distributed over the length of the reinforcing element.
8. A device according to any of the preceding claims, characterised in that the anchoring elements (4, 5, 13) form a continuous helix, at least over several turns, whose lead gradient is preferably in the region between 45° and 75°, with provision preferably being made for an end plate connecting the ends of the cut surfaces of the reinforcing element and the helix-type anchoring element mounted thereon.
9. A device according to any of the preceding claims, characterised in that the core cross-section (1) of the reinforcing elements has a higher degree of strength than their anchoring elements (3 - 5, 13).
10. A device according to any of the preceding claims, characterised in that the reinforcing element is designed as an open shear stirrup provided with anchoring elements.
11. A device according to any of the preceding claims, characterised in that the reinforcing elements (12a, b, c) are designed as pierce-through anchors provided along their entire length with anchoring elements (13), such reinforcing elements being preferably linked groupwise with a beam (14) to form shear reinforcement units.
12. A device according to any of the preceding claims, characterised in that at least one reinforcing element is designed as an element of a joint carrier provided with anchoring elements, comprising at least one tension bar and/or at least one compression bar and/or at least one diagonal bar.

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