DE102016217430B4 - expansion joint formwork - Google Patents

Abstract

Formwork for creating an expansion joint between a first section (BA1) to be concreted first and a second section (BA2) to be concreted after the latter in concrete construction, with a permanent formwork element (1) which contains a formwork wall containing a deformable separating joint insert (4) between cover plates (5) on both sides (3) and a supporting structure (15) which is firmly connected to the formwork wall (3) and is arranged on both sides of the formwork wall (3), and with a back-anchoring tension member (17, 22) which holds the formwork element (1) against the concrete pressure in the first section (BA1) back-anchored to the static reinforcement (14) or to the ground (2) on the first section side, characterized in that the back-anchoring tension member (17, 22) has a flexible tension element (17) that can exert tensile forces but essentially no compressive forces , Able to transmit, and the formwork wall (3) longitudinally movable passing through the second section side on the supporting structure (15) of the second section (BA2), esp is suspended in particular from a section of a stirrup arrangement (9) or a suspension rod (18) made of reinforcing steel, so that when concreting the first section the back-anchoring forces do not act as tensile forces on the parts of the formwork element (1), but rather as compressive forces from the second section (BA2). are introduced into the formwork element (1).

Description

The invention relates to a formwork for creating an expansion joint according to the preamble of patent claim 1.

Concrete structures are usually created in sections, with gaps forming between the concreting sections that are created one after the other. These are either construction joints, if the concreting sections abut directly, possibly with the interposition of a lost formwork, or expansion joints, if a gap remains between adjacent concreting sections, which is filled by a deformable separating joint insert. Expansion joints are provided so that the hardened concrete sections can expand under the influence of heat or can move relative to one another under the influence of forces on the structure without causing damage to the concrete.

At the boundary of a concreting section, formwork with a formwork panel is arranged, which prevents the concrete from running off the end face of the concreting section. The still flowable concrete exerts considerable hydrostatic pressure on the formwork panel. In order to prevent the formwork panel from being pushed away when pouring the concrete section to be produced first, it is known to provide a back-anchoring device. This has at least one tension member which is connected at one end to the formwork wall and at the other end to the static reinforcement or a ground anchor on the side of the formwork wall facing the initial concreting section. This creates a bracing of the formwork panel against the concrete pressure.

In the case of lost formwork for construction joints, for example, it is from the EP 2 157 260 A1 or from the EP 2 192 237 A2 It is known to use a rod-shaped tension strut as a back-anchoring tension member, which penetrates the formwork panel at one end and is secured there with a screw connection, while at the other end it is connected to the static reinforcement either directly or via a suspension bracket or a suspension loop. Such back-anchoring devices are very well suited for lost stop ends of construction joints. However, they are not suitable for creating expansion joints because an expansion joint must not be crossed by a rigid component in order not to impede the mobility of the concrete sections in the joint.

From the DE 20 2009 004 804 U1 In turn, formwork for construction joints is known, which consists of an expanded metal panel and a supporting and stiffening structure attached to the second section of this panel. For anchoring back to the reinforcement, a tension member consisting of a metal rod or a metal wire is provided, which is anchored to the reinforcement at the lower end by means of a shackle. At the upper end, the tension member is stretched through the formwork panel and then bent at its exit point so that it is essentially perpendicular to the plane of the formwork panel. An eccentric clamp is pushed onto this bent end and clamped. The eccentric clamp is supported on the supporting structure so that the tension element cannot be pulled back out of the formwork panel.

In the case of formwork for expansion joints, therefore, either a back anchor was not used, or the back anchor tension member was attached to the side of the formwork panel facing the first concreting section. The tensile forces occurring as a result of the concrete pressure between the formwork wall and the tension member lead to undesired deformations in the formwork panel or the other structural parts of the formwork element. This can only be prevented by a complex reinforcement structure, mostly consisting of lattice girders, on the side of the formwork element facing the first concreting section. Such additional measures are time-consuming and costly.

Finally, for example, from the DE 101 02 660 A1 and the DE 195 33 421 C1 , Already back-anchoring devices are known, which consist of ropes, wires or bands that are hung on the side facing the first section to be concreted on the formwork panel and hung at the other end in the reinforcement or an anchor. In this case, too, tensile forces arise on the formwork panel or the formwork element from the side of the section to be concreted first, which are difficult to absorb and deform the formwork.

The invention is therefore based on the object of creating a formwork that is particularly suitable for creating an expansion joint according to the preamble of patent claim 1, in which the back-anchoring forces resisting the concrete pressure are advantageously introduced into the formwork element and relative movements of the concrete components adjacent in the area of the expansion joint are not impeded .

This object is achieved according to the invention by the characterizing features of patent claim 1 in a generic formwork.

In the case of the formwork according to the invention, the anchoring in the back becomes the receptacle The tensile forces occurring as a result of the concreting pressure are conducted through the formwork panel by a flexible tension element and are introduced into the formwork panel as compressive forces from the side of the second concreting section via stable parts of the supporting structure. This avoids unfavorable loads on the parts of the formwork panel and the connection points of these parts with the supporting structure, since only compressive forces occur in the critical areas. A flexible tension element within the meaning of the invention is to be understood as meaning one that is able to reliably transmit the tensile forces occurring during back-anchoring, but deforms under pressure or under lateral loading without great resistance. If the end faces of the concrete parts adjacent to the expansion joint expand under the influence of heat and approach each other in the joint area, the tension element is merely compressed, but does not hinder the thermal movement of the concrete parts any more than the expansion joint filling compound compressing during this process. If the end faces of the concrete parts shift parallel to one another, shearing forces occur in the area of the tension element, which the tension element yields to without much resistance, so that it does not impede the free mobility of the concrete parts in this respect either. In extreme cases, the flexible tension member is sheared off during shearing movements of the concrete parts and in such a case acts as a kind of predetermined breaking element.

According to patent claim 2, a rope is particularly suitable as a pulling element. As is known, such a cable is composed of a plurality of twisted strands and is therefore able to transmit high tensile forces, while it can be easily compressed by compressive forces and bent laterally without great resistance.

According to patent claim 3, instead of a cable, a simpler and cheaper wire can also be used if the loads to be expected are not too great.

According to patent claim 4, metal, preferably steel, is suitable as the material for the tension element.

Since recently corroding components in joints of concrete structures are undesirable, shuttering panels are used whose cover plates are made of stainless steel. In such a case, the tension element is advantageously also made of stainless steel, so that this also does not introduce any corrosive materials into the expansion joint.

If the forces to be transmitted are not too great, the tension element can also consist of natural fibers, in particular hemp, or of plastic or of a mixture of these materials. This can save costs and solve the corrosion problem in a cheap way.

The pulling element consisting of a cable or wire advantageously has a diameter of between approximately 3 and approximately 8 mm. With smaller diameters, the risk of tearing during re-anchoring is too great, and with larger diameters, the flexibility of the tension element suffers.

Diameter dimensions between approx. 4 and approx. 5 mm have proven to be optimal for tension elements made of steel.

So that the tension element can move in the longitudinal direction relative to the formwork panel during back-anchoring, it is advantageously provided according to patent claim 9 that the tension element passes through the formwork panel in an opening with a diameter that is slightly larger than the diameter of the tension element. The difference in size should be selected in such a way that the tension element can move relative to the formwork panel without great resistance and without damaging the formwork panel when tensile forces are applied; however, the difference in diameter must be so small that no or only insignificant concrete can penetrate between the tension element and the edge of the opening.

Advantageously, the tension element has the features of claim 10. A tension element in the form of a closed loop can be anchored on both sides of the formwork panel in a simple manner by looping the loop around suitable rigid parts of the formwork element and either itself or with the intermediary of a tension rod on the reinforcement or a Ground anchor is attached.

• 1 einen Vertikalschnitt durch ein Schalungselement für eine Dehnfuge mit einem Teil eines Rückverankerungs-Zugglieds nach der Erfindung, eingesetzt in die statische Bewehrung einer zu betonierenden Sohlenplatte,
• 2 das Schalungselement nach 1 mit Rückverankerungs-Zuggliedern,
• 3 eine Detaildarstellung, und
• 4 eine der 2 entsprechende Schnittdarstellung mit gegenüber 2 geändertem Rückverankerungs-Zugglied.

Further features and advantages of the invention result from the following description of an exemplary embodiment in conjunction with the drawing. In this show:

• 1 a vertical section through a formwork element for an expansion joint with a part of a back-anchoring tendon according to the invention, inserted into the static reinforcement of a sole plate to be concreted,
• 2 the formwork element 1 with back-anchoring tension members,
• 3 a detail view, and
• 4 one of the 2 corresponding sectional view with opposite 2 modified rear anchorage tendon.

This in 1 and 2 illustrated embodiment of the invention has a two-part formwork element 1, which is used to shutter a floor slab on a blinding layer 2. The floor slab is concreted in the chronological sequence of a construction phase BA1 and a construction phase BA2. An expansion joint should be created between the construction sections.

The formwork element 1 has an upper part 1a and a lower part 1b. The formwork element 1 contains a two-part formwork wall 3, the upper part of which is denoted by 3a and the lower part of which is denoted by 3b. The two parts of the formwork wall 3 are made up of a central joint insert 4, for example a 20 mm thick mineral fiber board, and cover plates 5 covering the joint insert on both sides. The cover plates 5 and the parting line insert 4 are firmly connected to one another by means of screws 6. B. Styrodur, but also be glued together. At its upper edge in the installed state, the formwork wall 3 is bordered by a joint sealing strip 7 .

The cover plates 5 are composed of individual metal sheets. In the manner shown in the drawing, each sheet metal panel is folded at one edge that runs horizontally when installed or at both horizontal edges in such a way that folded legs protruding transversely from the shuttering wall 3 are produced. The cover plates are in the off 1 recognizable manner arranged in the assembled state that their folded legs rest flat against each other. The folding legs are firmly connected to one another in the abutting state, for example by spot welding, screws or rivets, so that double-walled spacers 8 are created, the function of which will be explained below.

The two parts of the formwork element 1 each have on both sides of the formwork wall 3 a support structure 15 with a bracket arrangement 9 that is used for transporting and handling the formwork element. Each bracket arrangement consists of metal rods bent several times, each of which has a section 9a which runs parallel to the plane of the formwork wall 3 and runs vertically in the installed state. For further details of the bracket assemblies 9, reference is made to FIG DE 20 2014 004 206 U1 referenced, the disclosure content of which is hereby made part of the content of the present disclosure.

The bracket assemblies 9 form in accordance with the assembled state 1 a joint tape cage 10, which accommodates a conventional elastic joint tape 11. The joint tape 11 is accommodated and clamped with its central, thickened part in a known manner in a slot 12 which is formed between the mutually facing edges of the shuttering wall parts 3a, 3b by positioning them at a certain distance from one another. Each stirrup arrangement 9 is firmly connected to the associated formwork wall part 3a, 3b via the above-mentioned spacers 8 by welding the exposed edges of the spacers 8, which run transversely to the stirrup bar sections 9a, to the latter. The cross-section L-shaped or U-shaped edges stiffen the cover plates 5 and thus the formwork wall 3 against bending under the concrete pressure. The stiffening effect is particularly pronounced because the spacers 8 consisting of the edging legs resting against one another are double-layered. At the same time, the spacers 8 form the connection between the parts 3a, 3b of the formwork panel 3 and the associated stirrup arrangements 9 in such a way that the stirrup arrangements with their rod sections 9a parallel to the formwork wall 3 have a sufficient distance of usually 30 mm in building construction and 60 mm in civil engineering.

The folding legs are angled slightly obliquely relative to the plane of the formwork wall 3 and in the installed state of the formwork element in the way that can be seen from the drawing, in order to facilitate the inflow of the concrete. The inclined position of the folding leg relative to the plane of the cover plates is about 15° relative to the vertical to the plane of the plate.

The formwork element 1 is set up and adjusted on the blinding layer 2 by means of support screws 13 .

In order to avoid the occurrence of corrosion in the expansion joint, a stainless steel is used as the material for the cover plates and expediently also for the screws 6. For example, grade 4.1016 steel is suitable. Since the distance between the surfaces of the shuttering wall 3 and the sections 9a of the bracket assemblies 9 is at least 30-60 mm, there is no corrosion-prone material within the concrete cover of the expansion joint, which improves the quality and, in particular, the service life of the joint. A material thickness of 0.5-1.0 mm is sufficient for the cover plates because of the reinforcement provided by the folds, which ensures that the expensive stainless steel material is used sparingly.

• In 1 ist erkennbar, dass die Schalungswand 3 im oberen und im unteren Teil Bohrungen 16 aufweist, deren Durchmesser im Bereich zwischen 6 und 20 mm liegen soll und vorzugsweise 8 mm beträgt. Durch die Bohrungen 16 ist je ein flexibles Zugelement 17 gesteckt, das bei dem dargestellten Ausführungsbeispiel als geschlossene Schlaufe ausgebildet ist, die im gezeigten Fall aus einem Drahtseil aus nicht-rostendem Stahl besteht. Das schlaufenförmige Zugelement 17 hat generell die Eigenschaft, im Wesentlichen nur Zugkräfte und keine Druckkräfte übertragen zu können, wie dies beispielsweise bei einem Seil der Fall ist, das auf Zug belastet werden kann, beim Auftreten von Druckkräften jedoch lediglich aufgestaucht wird.

How out 1 and 2 can be seen, the formwork element 1 is inserted into the static reinforcement 14 of the sole plate. About the ones from the concrete In order to be able to absorb the force exerted by pressure on the formwork element 1 without impermissibly shifting it, a back anchor is provided, the design of which according to the invention is described below:

• In 1 it can be seen that the formwork wall 3 has bores 16 in the upper and lower part, the diameter of which should be in the range between 6 and 20 mm and is preferably 8 mm. A flexible pulling element 17 is inserted through the bores 16, which in the illustrated embodiment is designed as a closed loop, which in the illustrated case consists of a wire rope made of stainless steel. The loop-shaped pulling element 17 generally has the property of essentially only being able to transmit tensile forces and no compressive forces, as is the case, for example, with a rope that can be subjected to tensile loads but is only compressed when compressive forces occur.

The tension member 17 is suspended on the supporting structure 15 on the side of the second section BA2 to be concreted after the first section BA1. For this purpose, a suspension rod 18 made of reinforcing steel is provided in the embodiment shown, which is welded between adjacent brackets 9 spaced apart from one another on the free edges of the spacers 8 or the folds of the cover plates.

The details of the construction described above are in 3 shown schematically on an enlarged scale. A clasp 19 can also be seen there, with which the ends of the cable loop 17 are connected to one another.

In addition, 3 An alternative construction is shown on the left, in which spacers 19a in the form of spatial lattice girders are arranged between the shuttering wall 3 and the bracket arrangement 9 or the suspension rods 18. In this case, the folded spacers 8 can then be omitted. The latter construction is particularly suitable if stainless steel is not used for the formwork element.

2 shows the formwork element 1 with complete rear anchoring. Since the parts of the formwork element are 1 in 2 are the same as in 1 , are in 2 no reference numbers denoting these parts are entered.

Out of 2 Back-anchoring tension members 20 can be seen, which consist of the already described loop-shaped, flexible tension elements 17 and tension rods 22 hooked into them on the side of the section BA1 to be concreted first by means of hook-shaped ends 21 . These tie rods 22 are hooked into the static reinforcement 14 at their ends 23 facing away from the hook-shaped ends 21 (only visible on the lower of the two tie rods 22).

In the exemplary embodiment shown, a bracket 25 that is angled multiple times is provided for hanging, as is detailed in 7-10 the EP 2 157 260 A1 illustrated and described in connection with these figures. The content of EP 2 157 260 A1 is made the subject of the present disclosure. This also applies to other bracket designs, as can be found in the publication mentioned.

The end 23 of the tension rod 22 is designed as a corrugated reinforcing steel rod on which a nut 26 can be screwed. Inserted between the nut 26 and the bracket 25 is a perforated flat bar 27 via which the nut 26 is supported on the bracket 25 . With this screw connection, the tension rod can be 22 in 2 be moved to the left, so that the loop-shaped tension members 17 passing through the bores 16 in a longitudinally movable manner are tensioned and the formwork element in 2 is pulled to the left against the static reinforcement 14.

When concreting the first section BA1, the concrete pressure is then transferred from the formwork panel 3 to the static reinforcement 14 via the back-anchoring tension members 20, and the formwork element 1 is back-anchored in this way.

It is essential that with the back anchoring according to the invention, the formwork panel 3 used to form an expansion joint is not penetrated by stiff components, but only by the flexible tension elements 17, which do not prevent the hardened concrete sections BA1 and BA2 from approaching each other under the influence of heat in the concrete structure and also Allow parallel displacement of the end walls of the adjacent concreting sections relative to the expansion joint, if necessary by shearing off the tension members. It is also important that the back-anchoring forces do not act as tensile forces on the parts of the formwork element 1, but rather are introduced into the formwork element as compressive forces from the second concrete section BA2. Pressure forces can be structurally better supported there. This applies both when the compressive forces from the suspension rod 18 are introduced into the formwork wall 3 via the spacers 8 or the sheet metal folds, and also in particular when a support element 19a ( 3 left) between the suspension rod 18 and the formwork panel 3 is inserted.

As already mentioned, in the exemplary embodiment shown, the pulling element 17 consists of a cable which is preferably twisted from strands made of stainless material. Alternatively, for cost reasons, a wire can also be used for the tension element. Both the rope and the wire are preferably made of metal, in particular steel, and the diameter should be between about 3 and about 8 mm and preferably about 4 to about 5 mm.

As in 3 shown, the strands of the loop-shaped tension element 17 can also be guided separately through bores 17 in the formwork wall 3 . The bores 16 can, instead of being perpendicular to the plane of the formwork wall, also be aligned obliquely through this plane, specifically in the direction of the tensile forces that occur, as shown in FIG 3 shown.

Instead of a metal cable, a cable or wire made from natural fibers, in particular hemp, or from plastic or from a mixture of these materials can also be used for formwork that is subject to less stress.

It is also conceivable to hang the tension element 17 instead of on its own suspension rod 18 in order to loop around a section of the bracket arrangement 9, in particular around one of the straight bracket sections 9a. In this case, an additional component is saved.

Instead of a loop-shaped pulling element, one consisting of a simple strand can also be used, which has suspension means such as hooks or eyelets at both ends, with which it can be attached to the supporting structure or a pulling rod.

Instead of hooking the tie-back tendon to the static reinforcement, it can also be hooked to a ground anchor.

In the embodiment according to 4 the formwork element 1 is constructed in exactly the same way as in 1 and 2 and will therefore not be described again.

Modified from the embodiment according to 1 and 2 is in 4 the tieback tendon 20'. It has an enlarged, loop-shaped pulling element 17 ′, which is again attached to the formwork element 1 on the BA2 side of the formwork element 1 at one end and hooked into a tie rod device 30 at the other end. This has a pull rod 31 made of corrugated reinforcing steel, which has a hook 32 on its end facing the formwork element 1 for hanging the loop-shaped pull element 17'. At the other end of the tension rod 31, a hook part 33 with a pierced foot 33a is slidably pushed onto it, which is adjustable with a tension nut 34 along the tension rod 31, so as to tighten the tie-back tension member 30. The hook part 33 is suspended with a hook end 33b in a cable loop 35 which in turn is anchored in the static reinforcement 14. The details of the latter construction are the EP 2 192 237 A2 in the 5 and the associated description. The Revelation of EP 2 192 237 A2 is made the subject of the present disclosure for this purpose.

Of course, the cable loop 35 can also be hooked into the reinforcement 14 or a ground anchor in a different way, for example simply looped around a crossbar of the reinforcement.

It is essential that also in the embodiment according to 4 the back-anchoring forces on the side of the second concrete section BA2 are introduced into the formwork element 1 as compressive forces.

Instead of the loop-shaped elements 17', 35, single-strand tension elements with hooks or eyes or other coupling parts at the ends can also be used, as long as it is ensured that these are essentially only able to transmit tensile forces, as is the case with ropes or wires.

Claims (10)

Formwork for creating an expansion joint between a first section (BA1) to be concreted first and a second section (BA2) to be concreted after the latter in concrete construction, with a permanent formwork element (1) which contains a formwork wall containing a deformable separating joint insert (4) between cover plates (5) on both sides (3) and a supporting structure (15) which is firmly connected to the formwork wall (3) and is arranged on both sides of the formwork wall (3), and with a back-anchoring tension member (17, 22) which holds the formwork element (1) against the concrete pressure in the first section (BA1) back-anchored to the static reinforcement (14) or to the ground (2) on the first section side, characterized in that the back-anchoring tension member (17, 22) has a flexible tension element (17) which exerts tensile forces but essentially no compressive forces , is able to transmit, and which penetrates the formwork wall (3) in a longitudinally movable manner on the second section side on the supporting structure (15) of the second section (BA2), in particular to a portion of a bracket assembly (9) or a suspension rod made of reinforcing steel (18) is hooked, whereby the concreting of the first section Reinforcement forces do not act as tensile forces on the parts of the formwork element (1), but rather are introduced into the formwork element (1) as compressive forces from the second section (BA2). formwork claim 1 , characterized in that the traction element (17) is a cable. formwork claim 1 , characterized in that the pulling element (17) is a wire. Formwork according to one of claims 2 or 3 , characterized in that the cable or wire is made of metal, preferably steel. formwork claim 4 , characterized in that the rope or wire is made of stainless steel. formwork claim 2 or 3 , characterized in that the rope or the wire consists of natural fibers, in particular hemp, or of plastic or of a mixture of these materials. Formwork according to one of Claims 2 to 6, characterized in that the rope or the wire has a diameter of approx. 3 mm to approx. 8 mm. formwork claim 7 , characterized in that the rope or wire has a diameter of about 4 mm to 5 mm. Formwork according to one of Claims 1 until 8th , characterized in that the tension element (17) passes through the shuttering panel (3) in at least one opening (16), the diameter of which is slightly larger than the diameter of the tension element. Formwork according to one of Claims 1 until 9 , characterized in that the tension element (17) forms a closed loop which passes through the formwork wall (3) in one or two openings (16) and which is looped around a suspension rod (18) or bracket (9) of the supporting structure (15) on the second section side and is suspended on the first section side at one end (21) of a rod-shaped tie rod (22), the other end (23) of which is suspended directly or via a suspension bracket (25) or a suspension loop from the static reinforcement (14) or from a ground anchor.

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