IMPROVEMENTS IN CANTILEVERED COUPLING OF A PRECAST CONCRETE SLAB TO A CONCRETE BUILDING ELEMENT

Abstract

 The disclosure relates to improvements in coupling of concrete slabs to concrete building elements of buildings, and includes a force transmission piece for use in a coupling that is arranged to cantileveredly connect a precast concrete slab to a concrete building element of a building, comprising a stiffening diagonal having a central bracket part that extends obliquely between an attachment part that is arranged to be attached to a head surface of the concrete building element of the building and a support part that is arranged to support the concrete slab and that in use is located lower than the attachment part, further comprising a pressure body with a head surface that is arranged for cooperation with the support part and a tail surface that is arranged for cooperation with the head surface of the concrete building element, which pressure body in use is enclosed in a gap between the support part of the stiffening diagonal and the head surface of the concrete building element.

Description

[0001] The invention generally relates to improvements in coupling of concrete slabs to concrete building elements of buildings. More specifically, the invention relates to improvement in cantilevered coupling of a concrete slab, in particular a precast concrete slab for e.g. a balcony, a parapet, a canopy or a walkway, to a concrete building element, e.g. a storey floor or wall element of a building. Such concrete building elements may be precast or cast in situ.

[0002] Precast concrete slabs are typically manufactured in a factory, and are transported to the building site. At the building site they may be connected to the concrete building element shortly after the concrete building element has been put into place, or later - e.g. when all floors of a building have been put up and the facade of the building is to be completed. Precast concrete slabs of a balcony, a parapet, a canopy or a walkway are typically connected to freely protrude from the facade of a building. The prefabricated concrete slabs for such cantilevered connection are typically placed without support, e.g. without temporary scaffolding. The prefabricated concrete slabs are normally hoisted into place using a crane, and are cantileveredly coupled to the concrete building element using a compound coupling acting between facing head surfaces of the concrete slab and the concrete building element respectively. The compound coupling may be embodied as a mechanical coupling, i.e. a coupling that relies on mechanical engagement of parts only to provide at least an initial load bearing connection between the concrete slab and the concrete building element. The compound coupling typically includes a tension coupling section forming an upper part of the compound coupling, and a compression coupling section forming a lower part of the compound coupling. The tension coupling section is a section of the compound coupling where tension forces are transmitted between the concrete slab and the concrete building element, and is typically located at the level of the top half of the concrete slab. The compression coupling section is a section of the compound coupling where compression forces are transmitted between the concrete slab and the concrete building element and is typically located at the level of the lower half of the concrete slab. The coupling sections may include building-sided and slab-sided coupling section parts, which each may comprise of several pieces. The coupling section parts may be coupled to reinforcement elements of the building element, and may be cast into the building element and slab respectively. The compound coupling may be arranged to improve thermal insulation between the concrete slab and the concrete building element, e.g. by including a thermal insulation body into a gap between the facing head surfaces of the concrete slab and the concrete building element that is provided by the compound coupling, and by using steel elements of low thermal conductivity in coupling section parts that traverse the gap. An example of such compound coupling is applicant's EP 0750 076.

[0003] Although quite satisfactory in many aspects, the efficiency of coupling may be improved, e.g. in terms of manufacturing pieces of the compound coupling itself, of manufacturing of the concrete building element and the precast concrete slab with the coupling section parts, and of the process of preparing the precast concrete slab and the concrete building element for coupling, and coupling them together. In particular, at least some pieces of the compound coupling are relatively complex and costly to manufacture, complicate the formwork for the precast concrete slab and concrete building element, and complicate preparing the precast concrete slab and the concrete building element for coupling, and coupling them together.

[0004] The invention aims to provide for an improved coupling with which one or more of the above disadvantages can be ameliorated. Thereto the invention provides for a force transmission piece for use in a coupling that is arranged to cantileveredly connect a precast concrete slab to a concrete building element of a building, comprising a stiffening diagonal having a central bracket part that extends obliquely between an attachment part that is arranged to be attached to a head surface of the concrete building element of the building and a support part that is arranged to support the concrete slab and that in use is located lower than the attachment part, further comprising a pressure body with a head surface that is arranged for cooperation with the support part and a tail surface that is arranged for cooperation with the head surface of the concrete building element, which pressure body in use is enclosed in a gap between the support part of the stiffening diagonal and the head surface of the concrete building element.

[0005] The provision of such force transmission piece allows for a simplified compression coupling section of a coupling for cantilevered coupling of a precast concrete slab to a concrete building element. As shall be discussed further below, such force transmission piece allows the compression coupling section to be manufactured more simply and less costly, allows simplification of the formwork for the precast concrete slab and the concrete building element, and allows facilitation of preparing the precast concrete slab and the concrete building element for coupling, and coupling them together. These advantages may i.a. be obtained because the force transmission piece may be formed as a separate component that may be coupled to a head surface of the concrete building element after casting, e.g. via bolt connection to a cast-in anchor in the concrete building element, and that may be built up using sheet material without need for welding. The force transmission piece may be releasably connected, and may be suspended from the head surface of the concrete floor.

[0006] The force transmission piece may be part of a compression coupling section of a compound coupling that further includes a tension coupling section. The compression coupling section may in use be located lower than the tension coupling section of the compound coupling. The tension coupling section may in use typically be located higher than the pressure body of the force transmission piece of the compression coupling section, and may typically include a set of cooperating building-sided and slab-sided tension section parts that may be anchored to the reinforcement elements of the concrete slab and the concrete building element respectively. The force transmission piece may be embodied in various configurations, and may include one or more of the following advantageous features and aspects.

[0007] The attachment part of the force transmission piece may extend in a flat plane, and may in use extend vertically. The central bracket part may extend in a flat plane, and may in use extend diagonally. The central bracket part may include a plurality of central members arranged in parallel, e.g. each with an individual attachment part and a common support member. The support part may extend in 1 or 2 flat planes, e.g. a substantially transverse or horizontal plane and/or a substantially upright or vertical plane.

[0008] The support part of the stiffening diagonal may be provided with a stop surface that extends at an angle to the central bracket part and that is arranged for cooperation with a lower side of the head surface of the concrete slab. Such stop surface may in use be oriented substantially vertically. When the stop surface of the support part is arranged to be inclined with respect to the attachment part, and in use cooperates with a beveled surface located at a lower part of the head surface of the concrete slab, a very efficient force transmission setup may be obtained. Such efficient force transmission setup makes use of a compression force that extends diagonally through the center of mass of the concrete slab, i.e. along the oblique side of a force triangle. This way, the compression coupling section may be free of slab-sided compression coupling elements, and free of anchoring means for such slab-sided compression coupling elements. This facilitates the formwork and manufacture of the precast concrete slab. The force transmission setup may thus be arranged for direct cooperation of the force transmission piece with the concrete slab, i.e. without use or interposition of a slab sided compression coupling section. Also when the stop surface is in use oriented substantially vertically, the compression coupling section may be free of slab-sided compression coupling elements, and free of anchoring means for such slab-sided compression coupling elements. The stop surface of the support part may alternatively be arranged to be inclined with respect to the attachment part, and to in use cooperate with an upright surface located at a lower part of the head surface of the concrete slab. The force transmission piece may in such embodiment be arranged for direct cooperation with an upright surface located at a lower part of the head surface of the concrete slab. The concrete slab may then be free of compression coupling elements and/or pressure coupling pieces.. A general advantage of direct cooperation of the head surface and the slab is that the head surface of the concrete slab may be free of slab-sided compression coupling elements and/or pressure coupling pieces, and the concrete slab may be free of anchoring means, protrusions and/or indentations for said slab-sided coupling elements. This facilitates lateral alignment between the concrete slab and the support. In addition, it facilitates manufacture of the concrete slab, in particular due to simplification of the formwork, especially when the concrete slab is free of slab-sided compression coupling elements and/or anchoring means for such said slab-sided coupling elements.

[0009] Preferably, the inclination angle of the beveled surface and the inclination angle of the stop surface relative to the vertical is the same. The inclination angle(s) may in particular be less than 30 degrees, and in particular be between 5-12 degrees. The pressure body may be oriented at a slant between the stiffening diagonal and the concrete building element. In particular it may extend at a slant from the stop surface of the stiffening diagonal to the pressure distribution plate at the head surface of the concrete building element. The pressure body may extend with a longitudinal axis thereof at a downward angle of slant relative to the horizontal in a direction from the concrete slab towards the concrete building element. The angle of slant may correspond in value to the angle of inclination of the beveled surface and the inclination angle of the stop surface relative to the vertical, an may in particular be between 5-12 degrees. In such an embodiment with a slanting pressure body, the longitudinal axis the pressure body may typically be not perpendicular to the head surface of the concrete building element, but may include an angle smaller than 90 degrees. In embodiments in which the pressure body extends with its longitudinal axis arranged horizontally, the longitudinal axis the pressure body may typically be perpendicular to the head surface of the concrete building element.

[0010] Further, the slab may be coupled to the force transmission piece by simply bringing the beveled surface of the concrete slab into engagement with the stop surface, e.g. by lowering it into position with adjustable chains of a crane. The force transmission piece may thus be arranged for hookless coupling to the concrete slab, i.e. the force transmission piece may be arranged with coupling devices, the coupling devices all being free of coupling elements that are arranged to be engaged with corresponding coupling elements by hooking into each other. The concrete slab can be coupled simply by hoisting it to the same height as the concrete building element, moving it towards the building, and subsequently connecting the tension coupling parts. As the coupling parts do not need to be hooked into place, tension bars of the tension couplings may protrude through holes that are closely sized to the diameter of the tension bars, and need not be oversized or oblong.

[0011] In an alternative embodiment in which the force is transmitted by separate compression and shear forces, the stop surface may extend vertically, and may cooperate with a straight vertical surface located at the lower part of the head surface of the concrete slab.

[0012] The force transmission piece may be provided with a pressure distribution plate that cooperates with the tail surface of the pressure body, and which in use is interposed between the tail surface of the pressure body and the head surface of the concrete building element. This facilitates distribution of compression forces transmitted from the compression body over the head surface of the concrete building element, and reduces demands made on the compressive quality of the concrete building element.

[0013] The pressure distribution plate may further cooperate with the attachment part, and may in use be interposed between the attachment part and the head surface of the concrete building element. This facilitates the connection of the force transmission piece to the concrete building element. The pressure distribution plate may be arranged to be detachably connected to the attachment part, e.g. via screws, to facilitate assembly of the force transmission piece, and to facilitate manufacture from sheet material. As an alternative, the pressure distribution plate may be provided on the concrete building element, and may e.g. be releasably or permanently connected thereto. In another embodiment, the pressure distribution plate may be integrally formed with the stiffening element, e.g. by bending it from sheet metal. In such embodiment, the attachment part and the pressure distribution plate may also be at least partially integrated. The attachment part may then also assume the function of the pressure distribution plate, or the attachment part may merge into the pressure distribution plate.

[0014] To improve thermal insulation between the precast concrete slab and the concrete building element, the force transmission piece may further be provided with a thermal insulation body that in use is included in an interspace between the support part of the stiffening diagonal and the head surface of the concrete building element. The thermal insulation body may advantageously be included between a building-sided part of the stop surface and a slab-sided part of the pressure distribution plate.

[0015] As set out above, the force transmission piece may be detachably connected to the concrete building element. This allows the formwork for casting the head surface of the concrete building element to be continuous and straight at the location of the force transmission pieces during casting, which facilitates making the formwork. The force transmission piece may be connected after casting of the concrete building element via the attachment part, e.g. by means of a bolt connection passing through a bolt hole in the attachment part. The force transmission piece may be connected to a part that is cast into the concrete element to serve as anchor, e.g. a concrete anchor that is cast into the concrete building element that forms a building-sided part of the compression coupling section, or e.g. a building-sided part of the tension coupling section. In such case, the concrete building element is cast with any building-sided part of the compression coupling section being embedded in the concrete and being enclosed by the formwork, i.e. without any building-sided compression coupling sections protruding through the formwork. The force transmission piece may be mounted to the head surface of the concrete building element, e.g. directly to the head surface or indirectly via the pressure distribution plate.

[0016] The pressure body may be oriented with a longitudinal axis thereof orthogonal to the stop surface. This way, in normal use only compression forces extending in longitudinal direction are transmitted, and in particular no shear force or bending moment. This allows the pressure body to be dedicated for transmission of compressive forces, and to be used with high efficiency. Elegantly, the pressure body of the force transmission piece may comprise a profile section, e.g. a cylindrical rod section, preferably a hollow profile section, e.g. a thin walled tube or box section of constant cross section.

[0017] The pressure body may extend along a longitudinal axis thereof between a head surface that is arranged for cooperation with a building-sided part of a stop surface of the support part, and a tail surface that is arranged for cooperation with the pressure distribution plate or the head surface of the concrete building element. In particular, the pressure body may extend along a longitudinal axis thereof between a head surface that extends perpendicularly to the longitudinal axis, the head surface being arranged for cooperation with a building-sided part of an inclined stop surface of the support part, and a tail surface, the tail surface extending transversely to the longitudinal axis at an angle corresponding to an inclination angle of the stop surface, and being arranged for cooperation with the pressure distribution plate or the head surface of the concrete building element.

[0018] At head and/or tail surfaces thereof the pressure body may be provided with lugs for cooperation with recesses that are provided in the stop surface and or pressure distribution plate, respectively. This way, the pressure body may be coupled to the stop surface and pressure distribution plate relatively easily, and may be stably secured thereto. In addition, the lug and recess connection allows for transfer of shear forces, e.g. at the tail surface of the pressure body in case it extends at an incline relative to the pressure distribution plate. Such lugged pressure body may e.g. be made cost effectively by laser or jet cutting the head and tail surfaces from a readymade steel hollow profile section, e.g. a thin walled box section or tube.

[0019] The attachment part may extend upwardly relative to a top of the central bracket part, and may e.g. be provided with a bolt hole. As an alternative, the attachment part may extend downwardly relative to a top of the central bracket part with inclusion of a support block. In such latter configuration, the support block may prevent the attachment part from being stripped off the bolt.

[0020] When at least the central bracket part of the stiffening diagonal is plate-shaped, preferably when the whole stiffening diagonal is plate-shaped, the stiffening diagonal may cost effectively be made of sheet material, in particular sheet steel. The stiffening diagonal and pressure distribution plate may be stamped or cut from sheet steel. The central bracket part, the attachment part and support part of the stiffening diagonal may be set from sheet metal using an angle bending machine, i.e. a press brake. This allows the stiffening diagonal to be manufactured cost effectively in one piece. In particular it allows it to be unwelded, i.e. free from welds, which are relatively costly for this type of components in view of the required quality assurance. Also the pressure plate can be manufactured cost effectively by stamping or cutting it from sheet steel without need for welding, and the stiffening diagonal and the pressure plate can be assembled together using screws or bolts, also without need for welding.

[0021] The support part may be provided with a support surface that extends at an angle to the central bracket part that is in use extends substantially horizontally, and is arranged for cooperation with a part of the underside of the concrete slab that is adjacent to the head surface. This facilitates coupling of the precast concrete slab to the concrete building element, as it allows the underside of the precast concrete slab to be temporarily supported by the support surface when it is lowered into its height position with adjustable chains of a crane. The support surface may also be used to support shims to facilitate levelling of the precast concrete slab supported on force transmission pieces interspaced along the concrete building element in a direction along the facade of the building, as well as to reinforce the edge of the precast concrete slab. When temporarily supported on the support surface, building-sided inner chains of the crane may be slackened, and the outer chains may be raised or lowered while the concrete precast concrete slab is levelled and the tension couplings are tensioned.

[0022] The force transmission piece may further be provided with one or more lips for coupling to an adjustment frame. Such adjustment frame may be used to align force transmission pieces interspaced along the concrete building element in a direction along to the facade of the building, in particular to align the interspaced force transmission pieces to support the precast concrete slab to be parallel to the facade of the building.

[0023] Due to the effects of weathering, it is advantageous if the components located in the joint between the concrete building element and the concrete slab, in particular of the force transmission piece, have weather-resistant properties and, especially when using steel, have noncorrosive properties. This can be achieved, for example, by using stainless steel, galvanized steel or a suitable surface coating. Stainless steel has the additional advantage of significantly lower thermal conductivity compared to e.g. black steel, ca. 15 W/(mK) vs. 50-60 W/(mK).

[0024] Preferably, the material of the force transmission piece thus is or includes steel, in particular stainless steel or galvanized steel. The invention further relates to a compound coupling, in particular a mechanical compound coupling, for cantilevered coupling of a precast concrete slab, in particular a balcony, to a concrete building element, the compound coupling including a compression coupling section comprising a force transmission piece according to any of the embodiments discussed above, and further including a tension coupling section. The compression coupling section may in use be located lower than the tension section of the compound coupling. The tension coupling section may in use typically be located higher than the pressure body of the force transmission piece of the compression section coupling, and may typically include a set of cooperating building-sided and slab-sided tension section parts that may be anchored to the reinforcement elements of the concrete slab and the concrete building element respectively.

[0025] The tension coupling section may further include a tension connector to which slab-sided and building-sided tension bars of the respective tension sections may be connected. The tension connector may e.g. be embodied as a steel tension plate. The tension connector may be held in either the concrete slab or the concrete building element, and may be provided with apertures through which tension bars of one of the tension sections may be introduced during coupling, and nuts to prevent the tension bars to be retracted through the apertures to secure the tension bars against the tension connector. Advantageously, the tension connector is included in the storey floor set back from the facade of the building, in particular at a distance from the head surface of the storey floor that corresponds to the thickness of a wall, to allow access to it after a wall has been placed on the storey floor. The material of the compound coupling, in particular the tension coupling section, is or includes steel, in particular stainless steel or galvanized steel.

[0026] Still further, the invention relates to a stiffening diagonal having a central bracket part that extends obliquely between an attachment part that is arranged to be attached to a head surface of a concrete building element of a building and a support part that is arranged to support a concrete slab and that in use is located lower than the attachment part. Such stiffening diagonal may be seen as an invention in its own, and may be used to couple concrete slabs to concrete building elements of buildings in general, in particular a precast concrete slab for e.g. a balcony, a parapet, a canopy or a walkway, to a concrete building element, e.g. a storey floor or wall element of a building. Such stiffening diagonal may advantageously include one or more of the following features.

[0027] At least the central bracket part of the stiffening diagonal may be plate-shaped. Preferably, the stiffening diagonal is plate-shaped.

[0028] The stiffening diagonal may be made of sheet material.

[0029] The central bracket part, attachment part and support part may be set from sheet metal.

[0030] The support part may be provided with a support surface that extends at an angle to the central bracket part and in use extends substantially horizontally, and that is arranged for cooperation with a part of the underside of the concrete slab that is adjacent to the head surface.

[0031] The force transmission piece may be provided with one or more lips for coupling to an adjustment frame.

[0032] The force transmission piece may be arranged for hookless coupling to the concrete slab, i.e. the force transmission piece being arranged with coupling devices, the coupling devices all being free of coupling elements that are arranged to be engaged with corresponding coupling elements by hooking into each other.

[0033] The force transmission piece may be arranged for direct cooperation with the concrete slab, and the concrete slab may be free of a slab-sided pressure coupling piece.

[0034] The material of the force transmission piece may be or may include steel, in particular stainless steel or galvanized steel.

[0035] The central bracket part may extend obliquely between the attachment part and the support part while including a stop surface. The stop surface may have an orientation that is different than another portion of the central bracket part, e.g. more inclined or upright. In addition, the central bracket part may extend obliquely between the attachment part and the support part while including lips, e.g. lips that are in use in contact with insulation, which lips may have an orientation that is different than another portion of the central bracket part, e.g. more inclined or upright.

[0036] The invention also relates to a precast concrete slab, in particular a balcony, a parapet, a canopy or a walkway, for cantilevered coupling to a concrete building element of a building, in particular a storey floor or wall element, in particular via a mechanical coupling, the concrete slab including slab-sided coupling section parts of a tension coupling of a compound coupling as set out above, located at an upper part of a head surface of the concrete slab that are arranged for mechanical coupling to corresponding building-sided coupling section parts, which slab-sided coupling parts are anchored to reinforcement elements of the precast concrete slab and are cast into the concrete slab. The precast concrete slab may be free of slab-sided compression coupling elements. A lower part of the head surface of the concrete slab may be arranged for cooperation with a force transmission piece, in particular a force transmission piece as discussed above. The lower part of the head surface of the concrete slab may include a beveled surface for cooperation with a force transmission piece as discussed above.

[0037] The invention furthermore relates to a concrete building element of a building, in particular a storey floor or wall element, including building-sided coupling section parts of a tension coupling of a compound coupling as set out above, located at an upper part of a head surface of the concrete building element that are arranged for mechanical coupling to corresponding slab-sided coupling section parts, which building-sided coupling parts are anchored to reinforcement elements of the concrete building element, and that are cast into the concrete building element, further comprising building-sided coupling section parts of a compression coupling located at a lower part of the head surface of the concrete building element, the building-sided compression coupling parts including a force transmission piece as discussed above, that is coupled as a separate component to the head surface of the concrete building element after casting via bolt connection to a cast-in anchor in the concrete building element. The force transmission piece may be suspended from the head surface of the concrete floor.

[0038] The invention still further relates to a building comprising a facade and at least one concrete building element, in particular a storey floor or wall element, to which at least one precast concrete slab, in particular a balcony, a parapet, a canopy or a walkway, has been cantileveredly coupled via a compound coupling as discussed above, the compound coupling including a building-sided compression coupling section comprising a force transmission piece according to any of the embodiments discussed above, and further including a tension coupling section including a set of cooperating building-sided and slab-sided tension section parts that have been anchored to the reinforcement of the concrete slab and the concrete building element respectively.

[0039] The invention also relates to a method of preparing the facade of a building for coupling of a concrete slab, in particular in particular a balcony, a parapet, a canopy or a walkway thereto, the method including the step of coupling a force transmission piece as discussed above as a separate component to a head surface of a concrete building element of the building, in particular a story floor or wall element, to a cast-in anchor in the concrete building element after casting of the concrete building element. The concrete building element may be cast in a formwork without any building-sided compression coupling sections protruding through the formwork.

[0040] The above aspects of the invention individually alleviate disadvantages, and in combination can alleviate disadvantages further. The above aspects of the invention together form an invention, but may each individually also be seen as inventions on their own.

[0041] The invention will further be elucidated on the basis of an exemplary embodiment which is represented in the drawings. The exemplary embodiment is given by way of non-limitative illustration of the invention.

[0042] In the drawings:

Fig. 1 shows a perspective top view of a compound coupling for cantilevered coupling of a precast concrete slab to an in situ cast storey floor in assembled and coupled condition,

Fig. 2 shows a perspective bottom view of a compound coupling for cantilevered coupling of a precast concrete slab to an in situ cast storey floor in assembled and coupled condition;

Fig. 3 shows a cross sectional view of a compound coupling of Fig. 1 for cantileveredly coupling a precast concrete slab to an in situ cast storey floor in uncoupled condition, and

Fig. 4 shows a cross sectional view of a compound coupling of Fig. 1 for cantileveredly coupling a precast concrete slab to an in situ cast storey floor in coupled condition.

[0043] Fig. 1 through 4 show an exemplary embodiment of a compound coupling 1 for cantilevered coupling of a precast concrete slab 2 of a balcony to an in situ cast concrete storey floor 3 as concrete building element. The compound coupling 1 can be used to connect precast concrete slabs 2 that form freely protruding balconies to concrete storey floors 3 after the floors 3 have been cast, e.g. when all storey floors 3 of the building have been put up and the facade of the building is to be completed. The concrete slabs 2 are placed without temporary support by hoisting them into place using a crane, and are cantileveredly coupled to the concrete storey floor 3 using the compound coupling 1 to act between facing head surfaces 4, 5 of the concrete slab 2 and the concrete storey floor 3 respectively. The compound coupling 1 is embodied as a mechanical coupling, i.e. a coupling that relies on mechanical engagement of parts only to provide at least an initial load bearing connection between the concrete slab 2 and the concrete storey floor 3. In this embodiment, two compound couplings 1 placed in parallel in coupled state together provide the final and full load bearing connection between the concrete slab 2 and the storey floor 3. The compound coupling 1 is arranged to improve thermal insulation between the concrete slab 2 and the concrete storey floor 3. It includes a thermal insulation body 6 in a gap 27 between the facing head surfaces 4, 5 of the concrete slab 2 and the concrete storey floor 3 provided by the compound coupling 1, and includes stainless steel elements of low thermal conductivity in the coupling section parts, in particular the coupling section parts that are at least partially located in or that traverse the gap 27.

[0044] The compound coupling 1 includes a tension coupling section 7 forming an upper part of the compound coupling 1, and a compression coupling section 8 forming a lower part of the compound coupling 1. The tension coupling section 8 is a section of the compound coupling 1 where tension forces are transmitted between the concrete slab 2 and the storey floor 3, and is located at the level of the top half of the concrete slab 2. The compression coupling section 8 is a section of the compound coupling 1 where compression forces are transmitted between the concrete slab 2 and the storey floor 3 and is located at the level of the lower half of the concrete slab 2. In Figure 4, a horizontal dashed line is drawn to illustrate the division between the lower half and the upper half of the concrete slab 2 and the concrete element 3. The compression coupling section 8 includes a force transmission piece 9 that shall be discussed more in detail below. The tension coupling section 7 is in use located higher than a pressure body 10 of the force transmission piece 9 of the compression coupling section 8. The tension coupling section 7 includes a set of cooperating building-sided and slab-sided tension coupling section parts 11, 12 that have been anchored to reinforcement bars of the concrete slab 2 and the concrete storey floor 3 respectively, and have been subsequently been cast in. The tension coupling section 7 includes a tension connector 13 to which slab-sided and building-sided tension bars 14, 15 of the respective tension coupling section parts 12,11 have been connected. In this exemplary embodiment, the tension connector 13 is embodied as a stainless steel tension plate held in the concrete of the storey floor 3. The tension connector 13 is provided with a row of apertures 16 that includes odd numbered and even numbered apertures. Connecting bolts 17 extend through the odd numbered apertures 16', and are screwed into threaded sockets 18 that are provided on the tension bars 15 of the building-sided tension part. Threaded ends 19 of the tension bars 14 of the slab-sided tension coupling are during coupling introduced through the even numbered apertures 16" via through holes 20 provided in the head surface 5 of the storey floor 3, and are secured via pressure plates with nuts on the threaded ends 19 to prevent the tension bars 14 to be retracted through the apertures 16". The holes 20 are relatively closely sized to the diameter of the tension bars 14, and need not be largely oversized or oblong. The tension connector 13 included in the storey floor 3 is set back from the head surface 5 of the storey floor 3, which here corresponds to the plane of the facade of the building, at a distance that corresponds to the thickness of a wall (shown smaller than to scale in Figs. 3 and 4). This still allows access to it after a wall has been placed on the storey floor.

[0045] The compression coupling section 8 is provided with a force transmission piece 9. The force transmission piece 9 comprises a stiffening diagonal 21. The stiffening diagonal 21 acts as a truss, and is used to properly position components of the force transmission piece 9 with respect to the cooperating head surfaces 4, 5. The stiffening diagonal 21 of this exemplary embodiment is made in one piece, but includes functional elements that can be distinguished as parts. In particular, the stiffening diagonal 21 has a central bracket part 22 that extends obliquely between an attachment part 23 and a support part 24 that is arranged to support the concrete slab 2. The attachment part 23 is arranged to be attached to the head surface 5 of the storey floor 3 of the building. The support part 24 is arranged to support the concrete slab 2. The support part 24 is in use located lower than the attachment part 23. As mentioned, the force transmission piece 9 further comprises a pressure body 10. The pressure body 10 is provided with a head surface 25 that is arranged for cooperation with the support part 24. The pressure body 10 is further provided with a tail surface 26 that is arranged for cooperation with the head surface 5 of the storey floor 3. The pressure body 10 is enclosed in a gap 27 between the support part 24 of the stiffening diagonal 21 and the head surface 5 of the storey floor 3.

[0046] The force transmission piece 9 is formed as a separate component of the compound coupling 1 and has been coupled to the head surface 5 of the concrete storey floor 3 after casting. In this example, it has been coupled to the head surface 5 of the storey floor 3 via bolt connection 28 to a cast-in anchor 29 in the storey floor 3. The force transmission piece 9 has been built up using sheet material without any weldings. The force transmission piece 9 is releasably coupled to the head surface 5 of the storey floor 3, and can e.g. be uncoupled for re-use or recycling. In this embodiment, the force transmission piece 9 is suspended from the head surface 5 of the concrete storey floor 3.

[0047] The attachment part 23 of the force transmission piece 9 extends in a flat plane, and in use extends vertically to match the orientation of the head surface 5 of the storey floor 3. The central bracket part 22 of the force transmission piece 9 also extends in a flat plane, and in use extends diagonally. In this embodiment, the central bracket part 22 includes a plurality of central members arranged in parallel, each with an individual attachment part 23 and a common support member. In this embodiment, the support part 24 extends in two flat planes, a substantially horizontal plane for temporary support of the concrete slab 2 during coupling to the storey floor 3 of the building, and a substantially upright plane for support of the concrete slab 2 during normal use.

[0048] At the substantially upright plane, the support part 24 of the stiffening diagonal 21 is provided with a stop surface 30 that extends at an angle to the central bracket part 22. The stop surface 30 is arranged for cooperation with a lower side of the head surface 4 of the concrete slab 2. The stop surface 30 is in this embodiment in use oriented substantially vertically, but not fully vertically. In this embodiment, the stop surface 30 of the support part 24 is arranged to be inclined with respect to the attachment part 23, and cooperates with a beveled surface 31 located at a lower part of the of the concrete slab 2. The stop surface 30 and the beveled surface 31 have substantially the same angle of inclination α, which is chosen to be 7° (shown enlarged), i.e. in the range of approximately 5-12 degrees with respect to the vertical. This way, a very efficient force transmission is obtained using a compression force extending diagonally through the center of mass of the concrete slab 2 to a bottom part 32 of the head surface 4, i.e. along the long side of a force triangle. In this embodiment, the pressure body 10 is used to transfer a large part of the gravity force acting on the concrete slab 2 to the storey floor 3 of the building.

[0049] The pressure body 10 is oriented at a slant to extend downward from the stop surface 30 of the stiffening diagonal 2 to the pressure distribution plate 35 and the head surface 5 of the concrete storey floor 3, i.e. in a direction from the concrete slab 2 towards the storey floor 3. The pressure body 10 extends through the gap 27 between the head surface 4 of the concrete slab 2 and the head surface 5 of the concrete storey floor 3 with a longitudinal axis 36 thereof at a downward angle of slant relative to the horizontal. The angle of slant corresponds in value to the angle of inclination of the beveled surface 31 and the angle of inclination of the stop surface 30 relative to the vertical. In this embodiment, the angle is 7° (shown enlarged).

[0050] The force transmission piece 9 is arranged for direct cooperation with the concrete slab 2. In the coupling process, as shall be discussed further below, the compression coupling section 8 of the compound coupling 1 can be engaged by simply supporting the beveled surface 31 of the concrete slab 2 on the stop surface 30 of the force transmission piece 9.

[0051] The compression coupling section 8 is free of slab-sided compression coupling elements, and the concrete slab 2 is free of anchoring means for such slab-sided compression coupling elements. This facilitates the formwork as it can be straight and closed at the lower end of the head surface 4 to be formed, and only requires boreholes to accommodate protruding slab-sided tension bars 14. Also, manufacture of the precast concrete slab 2 can be simplified, as no slab-sided compression coupling section need be provided that would otherwise need be anchored to the reinforcement bars of the concrete slab 2 and would need to be embedded in the concrete slab 2.

[0052] The support part 24 is provided with a support surface 33 that extends at an angle to the central bracket part 22 and that in use extends horizontally. The support surface 33 is arranged for cooperation with a part of the underside of the concrete slab 2 that is adjacent to the head surface 4. This facilitates coupling of the precast concrete slab 2 to the storey floor 3, as it allows the underside of the precast concrete slab 2 to be temporarily supported by the support surface 33 when it is lowered into position with adjustable chains of a crane. The support surface 33 can be used to support shims to facilitate levelling of the precast concrete slab 2 supported on the force transmission pieces 9 of two compound couplings 1 that are interspaced along the storey floor 3 in a direction along the facade of the building. The support surface 33 also serves to reinforce the lower edge 34 of the head surface 4 of the precast concrete slab 2 against pressure cracking.

[0053] The force transmission piece 9 is further provided with a pressure distribution plate 35 that cooperates with the tail surface 26 of the pressure body 10. The pressure distribution plate 35 is in use interposed between the tail surface 26 of the pressure body 10 and the head surface 5 of the storey floor 3. The pressure distribution plate 35 further cooperates with the attachment part 23, and in is interposed between the attachment part 23 and the head surface 5 of the storey floor 3. The pressure distribution plate 35 is detachably connected to the attachment part 23 via screws. The thermal insulation body 6 is included between a building-sided part of the stop surface 30 and a slab-sided part of the pressure distribution plate 35.

[0054] As set out above, the force transmission piece 9 is detachably connected to the storey floor 3. This allows the formwork for casting the head surface 5 of the storey floor 3 to be continuous and straight at the location of the force transmission pieces 9 during casting, which facilitates making the formwork for casting it. The force transmission piece 9 is connected after casting of the storey floor 3 via the attachment part 23, by means of a bolt connection 28 to a concrete anchor 29 that is cast into the storey floor 3. The force transmission piece 9 is in this case mounted indirectly onto the head surface 5 of storey floor 3, via the pressure distribution plate 35.

[0055] The pressure body 10 is oriented with its longitudinal axis 36 orthogonal to the plane of the stop surface 30. In normal use only compression forces extending in longitudinal direction are transmitted into and along the pressure body 10, and no shear force or moment. The pressure body 10 comprises a thin walled box section of constant cross section. The pressure body 10 extends along a longitudinal axis 36 thereof between a head surface 25 that extends perpendicularly to the longitudinal axis 36 that is arranged for cooperation with a building-sided part of the inclined stop surface 30 of the support part 24 and a tail surface 26 that extends transversely to the longitudinal axis 36 at an angle corresponding to the inclination angle that is arranged for cooperation with the pressure distribution plate 35 or the head surface 5 of the storey floor 3. The pressure body 10 is provided at the head and tail surfaces 25,26 with lugs 37 for cooperation with recesses 38 that are provided in the stop surface 30 and or pressure distribution plate 35 respectively. The lug 37 and recess 38 connection allows for transfer of shear forces at the tail surface 26 of the pressure body 10 where it extends at an incline relative to the pressure distribution plate 35. The shear force is transferred to the storey floor 3 via the pressure distribution plate 35 and the bolt connection 28. The lugs 37 at the head and tail surfaces 25, 26 have been provided by laser cutting the pressure body 10 from a readymade stainless steel thin walled tube of rectangular cross section with rounded corners.

[0056] The attachment part 23 extends upwardly relative to a top 39 of the central bracket part 22, and is provided with a bolt hole. The stiffening diagonal 21 is plate-shaped, and has been laser cut from stainless sheet steel. The central bracket part 22, the attachment part 23 and support part 24 of the stiffening diagonal 21 have been set using an angle bending machine. The stiffening diagonal 21 is manufactured in one piece, and is free from welds.

[0057] The force transmission piece 9 is further provided with a set of lips 40 for coupling to an adjustment frame. The adjustment frame is used to align force transmission pieces 9 that are interspaced along the storey floor 3 in a direction along to the facade of the building, in particular to align the interspaced force transmission pieces 9 to support the precast concrete slab 2 to be parallel to the facade of the building.

[0058] The coupling process is prepared as follows. When casting the concrete storey floor 3, an anchor 29 is cast into the concrete storey floor 3. The concrete storey floor 3 is cast in a formwork without any building-sided compression coupling sections protruding through the formwork.

[0059] Next, the facade of the building is prepared for coupling of the concrete slab 2 of the balcony, by coupling the force transmission piece 9 to the head surface 5 of the concrete storey floor 3. This is done by passing bolt 28 via the attachment part 23 and the pressure distribution plate 35 to the cast-in anchor 29 in the concrete story floor 3.

[0060] The coupling process is carried out as follows. The coupling process starts by hoisting the concrete slab 2 into position and moving it towards the facade of the building so that the tension bars 14 of the slab-sided parts 12 of the tension coupling section 7 protrude through the through holes 20 in the head surface 5 of the storey floor 3 and trough the apertures 16 in the tension connector 13. As shall be discussed further, the tension coupling parts can in a further step be fixedly coupled by screwing nuts onto the ends of the tension bars 14 of the slab-sided tension coupling.

[0061] After the concrete slab 2 has been moved towards the storey floor, e.g. from the position shown in Fig.3 to the position shown in Fig,4, so that the tension bars 14 protrude through the through holes 20 in the head surface 5 of the storey floor 3 and trough the apertures 16 in the tension connector 13, the precast concrete slab 2 is lowered slightly until a part of the underside of the concrete slab 2 that is adjacent to the head surface 4 is temporarily supported on the support surface 33 of the support part 24. When temporarily supported on the support surface 33, the building-sided inner chains of the crane may be slackened so that the concrete slab 2 rests on the stop surface 30 and optionally on the support surface 33, and the outer chains may be raised or lowered while the precast concrete slab 2 is levelled further, and the beveled surface 31 located at a lower part of the of the concrete slab 2 force cooperates with the beveled part the stop surface 30 of the support part 24. The tension coupling parts can then subsequently be fixedly coupled by screwing nuts onto the ends of the tension bars 14 of the slab-sided tension coupling.

[0062] Many variations will be apparent to the skilled person in the art. For example, the tension connector may be provided on the concrete slab instead of on the concrete building element, and the tension coupling section of the compound coupling may be embodied as another type of tension coupling. Also, the concrete building element may be precast instead of cast in situ as in the example, and may e.g. be a wall element instead of a storey floor. In addition, the attachment part of the force transmission piece may be connected to another part of the concrete building element, preferably a part that is cast into the concrete element to serve as anchor, e.g. a building-sided part of the tension coupling section. The precast slab may further e.g. part of a cantilevered parapet, canopy or walkway instead of a balcony as in the example. Such variations are understood to be comprised within the scope of the invention as defined in the appended claims.

List of reference signs

[0063] 

1. Compound coupling

2. Precast concrete slab

3. Concrete storey floor (Concrete building element)

4. Head surface concrete slab

5. Head surface concrete storey floor

6. Thermal insulation body

7. Tension coupling section

8. Compression coupling section

9. Force transmission piece

10. Pressure body

11. Building-sided tension coupling section parts

12. Slab-sided tension coupling section parts

13. Tension connector

14. Slab-sided tension bars of the slab-sided tension section

15. Building-sided tension bars of the building-sided tension section

16. Apertures tension connector (16'odd numbered, 16" even numbered)

17. Connecting bolts

18. Threaded sockets

19. Threaded end

20. Holes in storey floor

21. Stiffening diagonal

22. Central bracket part

23. Attachment part

24. Support part

25. Head surface of pressure body

26. Tail surface of pressure body

27. Gap between support part and head surface of storey floor

28. Bolt connection force transmission piece

29. Cast-in anchor

30. Stop surface

31. Beveled surface

32. Bottom part of head surface of concrete slab

33. Support surface of support part

34. Edge of concrete slab

35. Pressure distribution plate

36. Longitudinal axis pressure body

37. Lugs

38. Recesses in pressure distribution plate

39. Top of central bracket part

40. Lips

α Angle of inclination

Claims

1. Force transmission piece for use in a coupling that is arranged to cantileveredly connect a precast concrete slab to a concrete building element of a building, comprising a stiffening diagonal having a central bracket part that extends obliquely between an attachment part that is arranged to be attached to a head surface of the concrete building element of the building and a support part that is arranged to support the concrete slab and that in use is located lower than the attachment part, further comprising a pressure body with a head surface that is arranged for cooperation with the support part and a tail surface that is arranged for cooperation with the head surface of the concrete building element, which pressure body in use is enclosed in a gap between the support part of the stiffening diagonal and the head surface of the concrete building element.

2. The force transmission piece of claim 1, wherein the support part is provided with a stop surface that extends at an angle to the central bracket part and that is arranged for cooperation with a lower side of the head surface of the concrete slab.

3. The force transmission piece of claim 2, wherein the stop surface is in use oriented substantially upright.

4. The force transmission piece of claim 2 or 3, wherein the stop surface of the support part is inclined with respect to the attachment part, and in use cooperates with a beveled surface located at a lower part of the head surface of the concrete slab.

5. The force transmission piece of claim 3 or 4, wherein the stop surface includes an angle of inclination with respect to the vertical of less than 30 degrees, and in particular is between 5-12 degrees.

6. The force transmission piece of any of claims 1-5, wherein the force transmission piece is further provided with a pressure distribution plate that cooperates with the tail surface of the pressure body, and which in use is interposed between the tail surface of the pressure body and the head surface of the concrete building element.

7. The force transmission piece of claim 6, wherein the pressure distribution plate further cooperates with the attachment part, and in use is interposed between the attachment part and the head surface of the concrete building element.

8. The force transmission piece of claim 6, wherein the pressure distribution plate is integrally formed with the stiffening diagonal.

9. The force transmission piece of any of the preceding claims, wherein the force transmission piece is further provided with a thermal insulation body that in use is included in an interspace between the support part of the stiffening diagonal and the head surface of the concrete building element.

10. The force transmission piece of any of the preceding claims, wherein the force transmission piece is arranged to be detachably connected to the concrete building element.

11. The force transmission piece of any of the preceding claims 2-10, wherein the pressure body is oriented with a longitudinal axis thereof orthogonal to the stop surface.

12. The force transmission piece of any of the preceding claims, wherein the pressure body extends along a longitudinal axis thereof between a head surface that extends perpendicularly to the longitudinal axis, the head surface being arranged for cooperation with a building-sided part of an inclined stop surface of the support part, and a tail surface, the tail surface extending transversely to the longitudinal axis at an angle corresponding to an inclination angle of the stop surface, and being arranged for cooperation with the pressure distribution plate or the head surface of the concrete building element.

13. The force transmission piece of any of the preceding claims, wherein the pressure body extends with a longitudinal axis thereof at a downward angle of slant relative to the horizontal, in a direction from the concrete slab towards the concrete building element.

14. The force transmission piece of a claim 13, wherein the angle of slant is less than 30 degrees, and in particular is between 5-12 degrees.

15. The force transmission piece of any of the preceding claims, wherein the pressure body comprises a profile section, in particular a hollow profile section.

16. The force transmission piece of any of the preceding claims, wherein the pressure body at head and/or tail surfaces thereof is provided with lugs for cooperation with recesses that are provided in the stop surface and/or pressure distribution plate, respectively.

17. The force transmission piece of any of the preceding claims, wherein the attachment part extends upwardly relative to a top of the central bracket part.

18. The force transmission piece of any of claims 1-16, wherein the attachment part extends downwardly relative to a top of the central bracket part with inclusion of a support block.

19. The force transmission piece of any of the preceding claims, wherein at least the central bracket part of the stiffening diagonal is plate-shaped.

20. The force transmission piece of any of the preceding claims, wherein the stiffening diagonal is plate-shaped.

21. The force transmission piece of any of the preceding claims, wherein the stiffening diagonal is made of sheet material.

22. The force transmission piece of any of the preceding claims, wherein the central bracket part, attachment part and support part are set from sheet metal.

23. The force transmission piece of any of the preceding claims, wherein the support part is provided with a support surface that extends at an angle to the central bracket part that in use extends substantially horizontally, and that is arranged for cooperation with a part of the underside of the concrete slab that is adjacent to the head surface.

24. The force transmission piece of any of the preceding claims, wherein the force transmission piece is further provided with one or more lips for coupling to an adjustment frame.

25. The force transmission piece of any of the preceding claims, wherein the force transmission piece is arranged with coupling devices, the coupling devices all being free of coupling elements that are arranged to be engaged with corresponding coupling elements by hooking into each other.

26. The force transmission piece of any of the preceding claims wherein the force transmission piece is arranged for direct cooperation with the concrete slab, and wherein the concrete slab is free of a slab-sided pressure coupling piece.

27. The force transmission piece of any of the preceding claims, in which the material of the force transmission piece is or includes steel, in particular stainless steel or galvanized steel.

28. A compound coupling for cantilevered coupling of a precast concrete slab, in particular a balcony, a parapet, a canopy or a walkway, to a concrete building element, in particular a storey floor or wall element, including a compression coupling section comprising a force transmission piece according to any of the preceding claims, and further including a tension coupling section, the tension coupling section including a set of cooperating building-sided and slab-sided tension section parts that may be anchored to the reinforcement elements of the concrete slab and the concrete building element respectively.

29. The compound coupling according to claim 28, wherein the compression coupling section further comprises an anchor that is to be cast in into the concrete building element, and that after casting is to be coupled with the connection part of the force transmission piece via a bolt connection.

30. The compound coupling according to claim 28 or 29, wherein the tension coupling section further includes a tension connector to which slab-sided and building-sided tension bars of the respective tension sections are connected.

31. The compound coupling according to claim 30, wherein the tension connector is included in a concrete building element, in particular a storey floor a distance from the head surface of the building element that corresponds to the thickness of a wall.

32. The compound coupling according to any of the preceding claims, wherein the material of the compound coupling, in particular the tension coupling section, is or includes steel, in particular stainless steel or galvanized steel.

33. A precast concrete slab, in particular a balcony, a parapet, a canopy or a walkway, for cantilevered coupling to a concrete building element of a building, in particular a storey floor or wall element, the precast concrete slab including slab-sided coupling section parts of a tension coupling of a compound coupling according to any of claims 28-32, located at an upper part of a head surface of the precast concrete slab that are arranged for mechanical coupling to corresponding building-sided coupling section parts, which slab-sided coupling parts are anchored to reinforcement elements of the precast concrete slab and are cast into the concrete slab, the precast concrete slab being free of slab-sided compression coupling elements, at a lower part of the head surface of the concrete slab being arranged for cooperation with a force transmission piece, in particular a force transmission piece according to any of claims 1-27.

34. The precast concrete slab of claim 33, wherein the concrete slab includes a beveled surface located at a lower part of the head surface of the concrete slab for cooperation with a force transmission piece, in particular a force transmission piece according to any of claims 1-27.

35. A concrete building element of a building, in particular a storey floor or wall element, including building-sided tension coupling section parts of a compound coupling according to any of claims 28-32, located at an upper part of a head surface of the concrete building element that are arranged for mechanical coupling to corresponding slab-sided coupling section parts, which building-sided tension coupling section parts are anchored to reinforcement elements of the concrete building element, and that are cast into the concrete building element, further comprising building-sided compression coupling section parts of a compound coupling according to any of claims 28-32 located at a lower part of the head surface of the concrete building element, the building-sided compression coupling section parts including a force transmission piece according to any one of claims 1-27 that is coupled as a separate component to the head surface of the concrete building element after casting, via bolt connection to a cast-in anchor in the concrete building element.

36. A building comprising a facade and at least one concrete building element according to claim 35 to which at least one precast concrete slab according to claim 34, in particular a balcony, a parapet, a canopy or a walkway has been cantileveredly coupled via a compound coupling as claimed in any of claims 28-32.

37. A method of preparing the facade of a building for coupling of a concrete slab, in particular a balcony, a parapet, a canopy or a walkway thereto, the method including the step of coupling a force transmission piece according to any one of claims 1-27 as a separate component to a head surface of a concrete building element of the building, in particular a story floor or wall element, to a cast-in anchor in the concrete building element after casting of the concrete building element.

38. The method of claim 37, wherein the concrete building element is cast in a formwork without any building-sided compression coupling sections protruding through the formwork.

Drawing