Patent Application
20240417966
The invention relates to a wood-concrete composite slab having a planar wood element. Compared to pure concrete slabs, this slab is characterized by a considerably lower weight. Even compared to conventional wood-concrete composite slabs, the slab according to the invention provides a more lightweight and slender design. In this context, spans can be achieved with this slab system with very little dependence upon the relative inherent weight of the slab (i.e., calculated on the slab area). The invention further relates to a method for producing such slabs, a use, and a building having one or more such wood-concrete composite slabs.
Slabs having large spans are very desirable. Especially in multi-story and many-story buildings, such as high-rise buildings, they offer a gain in space utilization and variable options in the slab plan design of the stories. Moreover, large slab spanned dimensions also create flexibility in subsequent remodeling, because fewer load-bearing walls and columns have to be installed within a story. Achieving large slab spans also using wood-concrete composite slabs would be very desirable in every case.
A large spanned dimension, however, poses the same challenge to any slab planning: in order to be able to apply the required flexural rigidity and load-bearing capacity, the slab requires a sufficient static height. This in turn is reflected in its inherent weight—also in the case of a wood-concrete composite slab. In its conventional embodiment with the concrete on wood, the inherent weight of the slab then increases proportionally to the height. This places corresponding requirements on the vertical support structure and foundation of the building on which the loads have to be supported. In particular in high-rise construction with many stories, this represents a great challenge. Furthermore, a high slab thickness also has a negative effect on utilization, because fewer slabs can then be achieved for a certain height of a building. It would thus be desirable to be able to realize higher spans without the aforementioned disadvantages thanks to special wood-concrete composite slabs.
Although wood-concrete composite slabs with wood beams, i.e., with linear wood components, are already encountered in office and residential buildings, and sometimes also in high-rise buildings, the wood-concrete composite slab construction has not yet resolved all problems in order to be able to become established to the full extent. As the aforementioned slabs are used, viz., interspersed with wood beams, they are satisfying only to a limited degree from an architectural perspective. With the comparatively modest use of wood, merely as an axial grid through the slab, the ecological potential of the building material wood also cannot be sufficiently tapped. Quite apart from its properties as CO2 storage means, wood involves a comparatively low pollutant emission during processing, and likewise requires low energy consumption for the installation. The larger dimensioning of the wood component in a wood-concrete composite slab would consequently have only a positive effect on the climate impact of a building, which would be very desirable in any case. However, one is confronted here with two problems.
On the one hand, the use of more wood in the composite slab also calls for restrictive fire protection measures for the plan. It is true that static and architectural requirements could be met at the same time in the embodiment of a wood-concrete composite slab having a planar wood element, because such a slab can provide a finished and aesthetically appealing soffit as the bottommost composite layer. However, in this case, supports are in the way, which is why a combustible planar wood element cannot simply be exposed on the interior side—especially not in spaces with large spanned dimensions. The fire protection requirements tend to become more restrictive, the more slabs a building comprises, or the longer the evacuation paths are, wherein, of course, the use of and number of occupants in the building also play a role.
On the other hand, a larger proportion of wood in a wood-concrete composite slab means that it also offers less sound protection. As a substantially lighter composite partner than concrete, wood can much more easily be excited into vibrations. The structure-borne sound can therefore be propagated comparatively easily in a wood-concrete composite slab with a planar wood element and can be perceived by the building users. This prevents the use of such slabs—particularly in apartment buildings, in office buildings, for educational facilities like schools, universities, libraries, etc., and generally wherever high demands are placed on sound protection. In particular, this means that in buildings having separate utilization units, e.g., apartment and office units, room units of educational facilities, etc., which must be acoustically isolated from different parties using the building, the slab must be interrupted at the transition points of the individual units. This has a disadvantageous effect both on the slab statics and on the efficiency of the slab assembly.
The problems explained result in conventional wood-concrete composite slabs with a planar wood element with large spans not being usable: first, because of the proportional increase in inherent weight, secondly, because of the fire protection requirements, and, thirdly, because of the sound propagation. With such slabs, the utility or apartment units of a building ultimately cannot be appropriately spanned, so that comparatively small-span slab elements are still used, which also impairs construction and assembly efficiency.
Numerous constructions including wood and concrete components have become known in the prior art in the past decades. Some of such design suggestions are presented below.
U.S. Pat. No. 2,268,311 A, published in 1941, discloses a slab construction with a support structure made of concrete. The concrete upper slab with its downwardly projecting ribs, which are V-shaped in cross-section, is completely enclosed on its underside. A lower, horizontally running layer made of a plaster coating can be suspended in the finishing stage as follows: according to the embodiment shown in
In CH 223 498, published in 1942, a wood-concrete composite construction is presented in which the supporting wood component is designed in the form of wood beams. These wood beams have recesses on their upper side into which the concrete can penetrate from above and fill them. A shear-resistant surface adhesion is realized due to the interlocking of wood and concrete. Filling bodies—so-called Hourdi blocks—are laid between the wood beams and are each supported laterally on a wood beam. Here too, shear connections are realized only at the locations of the bearing means.
Another proposal for a wood-concrete construction is found in EP 0 280 228 A1, published in 1988. The supporting wood component of the slab structure presented therein is in turn designed in the form of beams running parallel to and spaced apart from one another. These form the lower slab closure. Above this, an insulating layer, over which the concrete upper slab comes to rest, is held by a formwork. The latter is connected to the wood beams via steel pipes. For this purpose, recesses are present both in the formwork and in the insulating layer, as a result of which the connecting pipes penetrate downwards into the wood beams. With its upper end portion, the connecting tubes are cast in the concrete of the upper slab. The shear connection is thus realized only at the locations of the bearing means.
DE 10 37 687 B, published in 1958, discloses a reinforced concrete rib or reinforced concrete beam slab. Cast-in-place concrete ribs formed at the bottom are framed in laterally by support rails made of wood, metal, or plastic. These support rails serve as supports for prefabricated concrete slabs. On the other hand, they interact with a plaster base arranged below them, viz., a tubular mesh mat, plate, or a lightweight plate, as permanent formwork for the cast-in-place concrete ribs. The support rails are on the one hand supported on a supporting wall, and on the other on a wooden yoke made of columns and cross-beams. The document does not disclose any shear connectors that engage into the concrete as well as into the support rails or into the wooden yoke.
The document FR 2 143 603 A1, published in 1973, discloses a slab construction which includes a steel beam with a cambered T-profile. Hourdi blocks, which constitute a permanent formwork, are placed on the shoulders of the cambered T-beam. The relatively thick middle layer of the Hourdi blocks is made of a foamed lightweight material (foamed polyurethane, Styropor, or material known under the brand name, Kégecell), covered at the top by an upper insulating layer of greater density (consisting of, for example, asbestos cement panels, gypsum board panels, or the like). Below the foamed lightweight material follows a layer of chipboard panels or the like. The insulating material of the upper Hourdi layer thus has a much greater density than the foamed light material of the thick, middle Hourdi layer, which in turn rests on the chipboard layer. A further layer of the same foamed lightweight material of the thick, middle Hourdi layer is suspended from these Hourdi blocks or nailed from below into the chipboard panels. This is also provided at the bottom with a plasterboard layer as a visual finish layer. Again, no shear connection with shear connectors protruding into the concrete and into the wood is disclosed.
US 2018/0328019 A1 shows a slab-ceiling panel made of a slab panel and a ceiling panel spaced apart therefrom with bearing means installed therebetween in the form of steel profiles having a C-shaped cross-section. The connection between slab and ceiling panels is formed solely by these metal bearing means consisting of aluminum or steel, which are screwed at the top to a metal partition wall layer and at the bottom into a slab layer advantageously consisting of non-combustible material. In the cavities formed between slab and ceiling panels, through which the metal bearing means also extend, an insulating material for thermal or acoustic insulation is placed at a distance from the lower ceiling layer.
Finally, a Brettstapel system is presented in US 2006/179741 A1, published in 2006. The individual Brettstapel elements are stacked on top of one another and are connected with hardwood dowels. For this purpose, holes are drilled into the Brettstapel elements into which the dowels are inserted. Because the moisture content of the dowels during installation is lower than that of the Brettstapel elements consisting of a softwood, a moisture equilibrium is established over time. The hardwood dowels here expand or swell. An isotropic pressure is produced that is directed radially onto the inner walls of the bore holes of the Brettstapel elements. The cohesion of the Brettstapel elements is due to this alone. The individual hardwood dowels preferably pass through the entire Brettstapel. Alternatively, however, a single hardwood dowel can also be designed to be shorter. However, the Brettstapel elements are not tensioned against one another, due to the contact pressure as a result of the dowels. However, the Brettstapel elements can be tensioned according to their length, for which purpose recesses are taken out in their bottommost portion, which recesses form channels when the Brettstapel elements are laid together, for inserting a cable or the like. Such a Brettstapel wood construction system is also suitable for wood-concrete composite slabs, as will be explained later.
In CA 2 176 450 A1, published in 1997, a wood beam consisting of numerous individual wood components stacked together in the transverse direction to the beam is presented. A cable which is tensioned on both sides of the wood beam leads through these wood components. For this purpose, an anchor plate or hollow box is applied to the outermost wood components of the beam, and the cable is finally tensioned thereon by means of a hydraulic press. This type of tensioning is suitable where space is present on both sides of a wood beam—for example, in the case of a boom which is mounted at a distance from its own concrete base.
With the exception of the two last documents mentioned above, all of the aforementioned solutions disclose bearing means (wood, concrete, metal bearing means) or projections from concrete of the concrete upper slabs that are formed to be downwards. It is thereby apparent that connections between the concrete and the wood run through the bearing means or projections of the concrete (regardless of whether the wood component of the corresponding construction assumes a supporting function at all). This leads to substantial weight concentrations of the slab at precisely these locations of the connection of concrete to wood. Such a wood-concrete connection accordingly correlates with the total weight of the slab. In general, it holds that, if wood-concrete connections, such as shear connectors, are arranged in one or more bearing means and/or in channels of the wood component filled with concrete or in projections of the concrete, the construction of a wood-concrete composite slab extending over large spans with substantial wood content and accordingly required strong connection to the concrete upper slab proves to be very challenging, as was explained at the outset with reference to the problem of large slab weight loads.
Against this background, the object of the present invention is to further tap into the energy-efficient construction potential of wood in a wood-concrete composite slab for the buildings mentioned at the outset. In particular, the slab should enable large spans with a low increase in weight. In this way, it should also be possible to use such units to cover spans in a comprehensive manner in terms of spaces and in buildings having separate residential, office, or utility units. Due to the nature of the slab, it should also be possible to close off spaces on the interior side with a layer made of wood, and thus a material which is in principle flammable, lightweight, and conducts sound well, while meeting fire protection and/or sound protection requirements. As a slab soffit, the wood layer is thus made distinctive in terms of interior architecture. The object is furthermore to specify such a wood-concrete composite slab and a method for efficient industrial production thereof, and a sound protection design of the wood-concrete composite slab using insulating material. Moreover, the object of the invention is to specify a building with one or more such wood-concrete composite slabs.
This object is achieved by combinations of features according to the invention, as are expressly defined below in accordance with the sections [0020] to [00120], and with reference to the claims in the section [00121]. Back references with section numbering are to be understood as subsidiary. Critical for the definitions of the invention here is the following: for a device defined with a minimum number of features (wood-concrete composite slab, building), any combinations with parts or all other device features are also disclosed as advantageous embodiments of the device. Similarly, for a method defined with a minimal number of features, any combinations with parts or all further method features are disclosed as advantageous embodiments of the method. Likewise, with all methods, a device (wood-concrete composite slab, building) with its various possible device features can be created or produced and is disclosed in each case as an advantageous embodiment of the method. In addition, the use in a device (wood-concrete composite slab, building) with its various possible device features can be realized and is therefore disclosed as an advantageous embodiment of the use.
The invention relates to a wood-concrete composite slab, the support structure of which comprises a component of concrete and a component of wood which is connected thereto in a shear-resistant manner, wherein the slab comprises a layer construction which, from bottom to top, includes, first, a wood component, viz., a wood layer, extended in a planar manner which can be subjected to a tensile load in the composite of the slab, followed by an insulating layer, and finally a concrete layer, wherein shear connectors are installed in the composite slab, with at least one shear connector simultaneously protruding into the wood layer and into the concrete layer, and thereby passing through the insulating layer, and wherein the layer construction of the slab is interrupted by at least one bearing means in that said bearing means traverses at least the concrete layer and the insulating layer and extends downwards at least as far as the wood layer.
According to one advantageous embodiment, the wood-concrete composite slab according to the invention comprises the combination of the features according to section [0020], wherein the at least one bearing means projects over its length partially or completely out of the composite slab in that is projects downwards and/or upwards out of the same.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises the combination of the features according to one of sections [0020] or [0021], wherein the projection, which is partially shaped downwards over its length, of the bearing means is designed as a capital of a column adjacent to the bearing means.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0020] to [0022], wherein the at least one bearing means contains reinforcing steels and/or a steel profile having at least one lower flange as reinforcement.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0020] to [0023], wherein the one or more bearing means is/are dimensioned in terms of their number such that their weight is up to 10% of the total weight of the slab.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0020] to [0024], wherein, in the case of an up to 50% extension of the span of the composite slab, up to a total length of 9 m of the extended span, the span-dependent weight increase of the slab does not exceed 10% of the slab weight, and the slab thickness varies by only 5-10 cm, in order to ensure greater flexibility in the slab plan design.
The invention also relates to a method for producing a wood-concrete composite slab having any combination of features according to one or more of sections [0020] to [0025], with at least two slab modules,
According to an advantageous embodiment, the method comprises the combination of the features according to section [0026], wherein, for each slab module,
According to a further advantageous embodiment, the method comprises the combination of features according to one of sections [0026] or [0027], wherein, for a bearing means projecting at the top,
The invention further relates to a wood-concrete composite slab the support structure of which comprises a component of concrete and a component of wood which is connected thereto in a shear-resistant manner, wherein the slab comprises a layer construction which, from bottom to top, includes, first, a planar wood component, viz., a wood layer, which can be subjected to a tensile load in the composite of the slab, followed by an insulating layer, and finally a concrete layer, wherein shear connectors are installed in the composite slab, of which at least one shear connector simultaneously extends into the wood layer and into the concrete layer and in doing so passes through the insulating layer, wherein the insulating layer comprises at least two insulating materials of different densities or specific weights, and the denser insulating material is arranged directly on this wood layer in the slab composite and can be subjected to a tensile load or rests directly thereon, which increases the inertia of the wood layer and is intended to act as a vibration damping means.
According to an advantageous embodiment, the wood-concrete composite slab according to the invention comprises the combination of the features according to section [0029], wherein the layer construction of the slab either extends without bearing means over the slab, or at least one bearing means traverses at least the concrete layer and the insulating layer, and consequently extends downwards at least as far as the wood layer.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises the combination of the features according to one of sections [0029] or [0030], wherein an upper layer of less dense insulating material rests on a lower layer of denser insulating material.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0029] to [0031], wherein a cavity is formed in the slab so that the less dense insulating material consists of air, wherein the concrete layer rests on a permanent concrete formwork above the cavity.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0029] to [0032], wherein air is excluded as a material for the less dense insulating material, or the slab is free of cavities made up of air.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0029] to [0033], wherein the difference in the densities or specific weights of the insulating materials is 0.5 to 2 t/m3.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0029] to [0034], wherein the contact pressure of the denser insulating material is between 0.7 and 1.4 kN per m2, and the contact pressure of the less dense insulating material is between 0.1 and 0.4 kN per m2.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0029] to [0035], wherein the denser insulating material consists of a concrete granulate made of crushed concrete or of a mixed granulate of crushed concrete and masonry, and the less dense insulating material consists of lightweight building material.
Furthermore, the invention relates to a use of at least two insulating materials of different densities or specific weights as sound protection by means of vibration damping of the wood layer in a wood-concrete composite slab according to any combination of features according to one or more of sections [0020] to [0036], or a use of at least two insulating materials of different densities or specific weights in direction-dependent arrangement or direction-dependent sequence as sound protection by means of vibration damping of the wood layer in a wood-concrete composite slab according to any combination of features according to one or more of sections [0020] to [0036].
In addition, the invention relates to a method for producing a wood-concrete composite slab according to any combination of features according to one or more of sections [0029] to [0036] with at least two slab modules,
According to an advantageous embodiment, the method comprises the combination of the features according to section [0038], wherein, for each slab module,
The invention further relates to a wood-concrete composite slab, the support structure of which comprises a component of concrete and a component of wood which is connected thereto in a shear-resistant manner, wherein the slab comprises a layer construction which, from bottom to top, includes, first, a planar wood component, viz., a wood layer, which can be subjected to a tensile load in the composite of the slab, followed by either an insulating layer and finally a concrete layer, or, in the absence of the insulating layer, is followed or directly followed by a concrete layer, wherein the wood layer includes at least two abutting wooden panels, which are reciprocally tensioned against one another, in that the one wooden panel presses perpendicularly against the other wooden panel at a parting plane formed when they abut, wherein, in each of the wooden panels tensioned against one another in this way while leaving intact their underside, at least one recess is created by material removal in such a way that the at least one box-shaped space is formed in the wooden panel and with a recess of the wooden panel located on the remote side of the parting plane forms a recessed passage that spans across the two wooden panels, wherein the wooden panels, as viewed from the parting plane, are left intact in a space extending behind their one or rear box-shaped space in a direction perpendicularly away from the parting plane and therefore form there a rear intact material for other use, wherein the tensioning means are introduced in the passage and anchored at each end in at least one box-shaped space, so that the wooden panels are tensioned against one another as a result of the tensioning means being tightened.
According to an advantageous embodiment, the wood-concrete composite slab according to the invention comprises the combination of the features according to section [0040], wherein the layer construction of the slab either extends without bearing means over the slab, or at least one bearing means traverses at least the concrete layer and the insulating layer when an insulating layer is present, and as a result extends downwards at least as far as the wood layer.
According to an advantageous embodiment, the wood-concrete composite slab according to the invention comprises the combination of features according to section [0040] or [0041], wherein the region which is left intact adjoins directly behind the one or rear box-shaped space and extends in a direction perpendicularly away from the parting plane.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0042], wherein the region which is left intact extends either as far as one end of the wooden panel which is opposite the end, located at the parting plane, of the wooden panel, or the region extends as far as a box-shaped space of the same wooden panel arranged for tensioning with a further wooden panel.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0043], wherein the tensioning means bears against a location, upstream of the parting plane, within the wooden panel.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0044], wherein the tensioning means does not bear directly against a parting plane or an end face of the wooden panel.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0045], wherein the at least one box-shaped space is designed to be open towards the top or open towards the top and at the end.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0046], wherein the at least one box-shaped space for accommodating an anchoring of the tensioning means is rectangular.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0047], wherein either
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0048], wherein the passage spanning across the two wooden panels is removed symmetrically with respect to the parting plane, so that the recesses of the wooden panels can be produced identically and/or the tensioning means can be used independently of the side, and/or the tensioning means can be used independently of the side, so as to act orthogonally to the parting plane.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0049], wherein the tensioning means components form an arrangement symmetrical to the parting plane, and/or the tensioning means components are laid so as to act orthogonally to the parting plane.
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0050], wherein the tensioning means is realized
According to a further advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0040] to [0051], wherein the recesses each form—as viewed from the parting plane—a rear chamber and a front chamber which are connected via a hollow channel in the front intact material, as a result of which said front intact material is not intact solely due to the hollow channel, or as a result of which said front intact material is not intact solely due to the hollow channel for the tensioning means acting orthogonally to the parting plane, wherein the tensioning means is anchored in each end in the rear chamber by means of screw heads or tensioning blocks, and the front chamber of a near-side wooden panel in each case forms a common chamber open at the top with the front chamber of the wooden panel located on the remote side of the abutment axis, wherein a continuous threaded connection is realized via the hollow channels and the common chamber, which thread connection can be tensioned in the common chamber either by fixed-location rotation of a sleeve, by a coupling including a central nut and two threaded pipe sections which can be pulled together by said nut, or by a nipple.
Furthermore, the invention relates to a method for producing a wood-concrete composite slab according to any combination of features according to one or more of sections [0040] to [0052], in that,
According to an advantageous embodiment, the method comprises the combination of features according to section [0053] in that
According to a further advantageous embodiment, the method comprises the features according to one of sections [0053] or [0054], wherein
According to an advantageous embodiment, the wood-concrete composite slab according to the invention comprises any combination of features according to one or more of sections [0020] to [0025], [0029] to [0036], [0040] to [0052] and one or more of the features presented in the following sections [0057] to [00111], viz:
In addition, the invention relates to a building comprising one or more installed wood-concrete composite slabs having any combination of features according to one or more of sections [0020] to [0025], [0029] to [0036], [0040] to [0052], [0056] to [00111].
An advantageous embodiment of the invention relates to a building having the combination of features according to section [00112], wherein it is designed as a residential and/or office building, administrative building, educational facility, exhibition hall or civic center, conference and concert hall, library, museum, repository, shopping center, hotel, aquatics center, sports stadium, train station, or airport.
A further advantageous embodiment of the invention relates to a building having the combination of features according to any of sections [00112] or [00113], wherein it is designed as a high-rise building with a total height starting at 25 m.
A further advantageous embodiment of the invention relates to a building according to one or more of sections [00112] to [00114] with one or more built-in wood-concrete composite slabs having any combination of features according to one or more of sections [0020] to [0025], [0029] to [0036], [0040] to [0052], [0056] to [00111], wherein the slabs are installed in a horizontal position and/or in an oblique position up to 45° or in an oblique position up to 60°.
An advantageous embodiment of the invention also relates to a method having any combination of features according to one or more of sections [0026] to [0028], [0038] to [0039], [0053] to [0055].
A further advantageous embodiment of the invention relates to a method having any combination of features according to one or more of sections [0026] to [0028], [0038] to [0039], [0053] to [0055] for creating a wood-concrete composite slab having any combination of features according to one or more of sections [0020] to [0025], [0029] to [0036], [0040] to [0052], [0056] to [00111].
A further advantageous embodiment of the invention relates to a method having any combination of features according to one or more of sections [0026] to [0028], [0038] to [0039], [0053] to [0055] for the creation of a building having any combination of features according to one or more of sections [00112] to [00115].
In addition, an advantageous embodiment of the invention relates to a use having the combination of features according to section [0037] in a wood-concrete composite slab having any combination of features according to one or more of sections [0020] to [0025], [0029] to [0036], [0040] to [0052], [0056] to [00111].
A further advantageous embodiment of the invention relates to a use having the combination of features according to section [0037] in a wood-concrete composite slab having any combination of features according to one or more of sections [0020] to [0025], [0029] to [0036], [0040] to [0052], [0056] to [00111], which is built into a building having any combination of features according to one or more of sections [00112] to [00115].
The object of the invention is also achieved by a wood-concrete composite slab having the features according to any of claims 1, 10, or 20. Advantageous embodiments of the wood-concrete composite slab according to the invention are described in dependent claims 2 to 6, 11 to 16, 21 to 30, and 34 to 86. The object is also achieved by a method having the features according to any of claims 7, 18, or 31 and advantageous embodiments of the method according to claims 8 to 9, 19, 32 to 33, and 91 to 93. Furthermore, the object of the invention is achieved by a use according to claim 17 or as an advantageous embodiment of the use according to any of claims 94 or 95. The object is also achieved by a building according to claim 87 and advantageous embodiments of the building according to claims 88 to 90.
Because large spans can be spanned with the wood-concrete composite slab according to the invention and at the same time have an attractive appearance, they can find extremely wide and versatile application, not only in residential buildings, but also in office buildings and public administration buildings—in particular, with open plan office design—in schools and educational facilities, but also in especially large-sized buildings such as meeting facilities, exhibition halls and civic centers, conference and concert halls, libraries, museums, repositories, shopping centers, hotels, aquatics centers, sports stadiums, train stations, and airports, just to name a few such buildings with typically large-area slabs. A typical field of use of the slab according to the invention relates to multi-story construction—in particular, high-rise construction—because, as a rule, apartments and/or office units are to be accommodated there of different sizes and varying layouts, and the slab offers this flexibility thanks to the spanned dimension that can be realized therewith. In contrast to a conventional slab system, the wood-concrete composite slab according to the invention also brings with it relief to the support structure and foundation of the building—especially in high-rise buildings. And even if high requirements are placed on sound protection, the slab design according to the invention can stand out due to its comparatively lightweight design. In this way, it simultaneously meets modern demands for sustainable, low-impact construction and living quality, and is therefore excellently suited for urban multi-story construction and high-rise construction. The height of a building at which it qualifies as a high-rise building according to the applicable standards usually varies between about 25 and 50 meters for its overall height. In the following, a high-rise building is always understood to be a building starting at an overall height of about 25 meters. It goes without saying that the slab according to the invention can also be installed advantageously in less complex or less requirement-heavy building structures, and its application area generally, although not exclusively, relates to the high-rise construction.
In the figures, the wood-concrete composite slab according to the invention and a building having one or more such built-in slabs are illustrated based upon exemplary embodiments, and their peculiarities and their production are described and explained in detail in the following description.
In the drawings:
a: shows an example of a conventional wood-concrete composite slab with linear wood components and connecting elements running along the same, in a perspectival plan view;
b: shows an example of a conventional wood-concrete composite slab with a planar wood element made of Brettstapel with connecting elements running in grooves of the same, shown partially cutaway in perspectival plan view;
a: shows a cross-section through the layer construction of an embodiment of the wood-concrete composite slab according to the invention having a reinforced concrete bearing means embedded internally in the slab;
b: shows a cross-section through the layer construction of an embodiment of the wood-concrete composite slab according to the invention having an bearing means embedded internally into the slab, which bearing means includes a steel beam;
a: shows a longitudinal section through a wooden panel with a loosely inserted anchor for the tensile-force connection to a further wooden panel;
b: shows a longitudinal section through two abutting wooden panels, before producing a tensile-force connection of the wooden panels;
c: shows the longitudinal section through the configuration according to
b, but now with wooden panels tensioned to one another in a frictional manner;
d: shows a longitudinal section through two abutting wooden panels, which are tensioned against one another with a loosely inserted tensioning lock;
e: shows a tension spindle with threaded rods and a sleeve running thereon;
f: shows a cross-section through the spared/remaining/untouched front intact material of a wooden panel, with differently shaped incisions or milled-out portions for the tensioning means connection, with a view in the direction of the abutment axis relative to the parting plane of the wooden panels;
g: shows a longitudinal section through two abutting wooden panels, which are tensioned against one another with a tensioning closure screwed into the wooden panels;
h: shows a cross-section through a recess in a wooden panel with a laterally anchored tensioning block;
i: shows a longitudinal section through two abutting wooden panels which are tensioned against one another by wedge tensioning;
j: shows a tensioning wedge having a U-shaped incision or milled-out portion, whereby it can be slipped over a threaded rod;
k: shows a longitudinal section through two abutting wooden panels that are tensioned against one another in a tensioning arrangement which is symmetrical along the parting plane of the wooden panels;
a-m: shows a method for producing a wood-concrete composite slab according to the invention in chronological sequence;
b: shows a section through the support configuration according to the section line A-A in
For the present disclosure, some terms are defined below:
First, a cutout of a conventional wood-concrete composite slab having linear wood components is described and explained with reference to
b shows a cutout of an alternative embodiment of a conventional wood-concrete composite slab, viz., a planar wood-concrete composite slab. The wood support structure is designed as a planar wood element or as a wood layer 1, mostly made of a wood material, such as cross-laminated timber, glue-laminated lumber, laminated veneer lumber, or solid wood. In the example shown here, the wood layer 1 is formed from board layers which are arranged vertically one after the other and stacked edgewise on top of one another and are also Brettstapel elements. For a glue-free joining of these elements, kiln-dried hardwood dowels are installed into the elements perpendicular to their surface, and precise-fit boreholes are introduced into the respectively adjacent elements. After the outer-dry dowels have been inserted into the boreholes of the respectively adjacent Brettstapel element, when the wood dowels are enriched with moisture, they swell up and are thus compressed within the boreholes. Grooves or channels 7 spaced apart from one another are made in the wood layer 1 formed in this way. Connecting elements 6, here in the form of dowels or screws, are introduced therein as shear connectors perpendicular to the slab surface. After the concrete layer 4 has been created, the channels 7 then filled with concrete act with their connecting elements 6 as shear joints. Also in this embodiment of the wood-concrete composite slab, a minimum reinforcement is inserted into the concrete layer 4 for absorbing the tensile stresses and avoiding cracking. Such a conventional planar wood-concrete composite slab can well be realized in single-family buildings or other buildings having small slab spans and low protection specifications. The larger the slab construction becomes, and the higher the protection specifications of a building are, the less worthwhile it is to use them.
In order to be able to expediently use conventional wood-concrete composite slabs in multi-party buildings, high-rise buildings, or other large-sized buildings, greater requirements for their load-bearing capacity are set—in particular, if large/long spans are to be realized. As explained at the outset, the design thickness of the slab, i.e., its height, must then be more pronounced so that it becomes more flexurally rigid. For a conventional slab structure as shown in
a shows a cross-section through the layer construction of an embodiment of the wood-concrete composite slab according to the invention having a planar wood element. In this embodiment, it has as a special feature a linear bearing means which is enclosed within the spatial extension of the slab and is consequently referred to below as an “internal bearing means.” In this case, it passes through at least the concrete layer 4 and the insulating layer 3, and thus interrupts the layer construction 3, 4 of the slab so that the composite layers 3, 4 spatially adjoin each lateral flank 16 of the bearing means 8 thereof, i.e., adjoin it on both sides, which extends in its length perpendicularly to the sheet plane in
The use of wood-based materials, such as cross-laminated timber (CLT), and in particular also laminated veneer lumber (LVL), proves to be advantageous for the wood layer 1. Compared to fiber-parallel arrangements of laminate layers, those with a crosswise-laid portion basically lead to an increased directional independence of the laminate, and consequently to more stiffness and strength of the laminate as a whole. Sometimes, this allows a slender design of the wood layer 1. Glass- or carbon-fiber-reinforced variants of such cross-layered, wood-based materials are also suitable for a flexurally rigid wood layer 1. Preferably, an LVL of beech wood is used, which in German-speaking technical circles is referred to as “BauBuche.” Thanks to the extraordinarily high strength and stiffness, BauBuche can be processed into substantially thinner components compared to softwood materials. In a typical embodiment of the slab, the wood layer 1 forms a 60 mm thick—and thus only approximately half as thick—subslab, as in comparable planar wood-concrete composite slabs according to prior art.
An insulating layer 3 is accommodated in the intermediate space between wood layer 1 and concrete layer 4. In an advantageous embodiment variant of the invention, the insulating layer 3 is designed in multiple layers made of insulating materials of different densities or different specific weights, with the layer of greatest density situated below on the wood layer 1. This will be discussed later. As a result of the spacing of the upper concrete slab from the wood subslab 1, a static height is created which affords a large flexural rigidity. In the present example, this spacing or the height of the intermediate space is 170 mm and is usually also designed to be between 100 and 250 mm high—preferably between 120 mm and 190 mm—in other embodiments of the slab. Between the wood layer 1 and the concrete layer 4, shear connectors 9 in the form of steel pipes are installed vertically thereto in this embodiment. The load-bearing concrete and wood layer 1, 4 are connected to one another in a shear-resistant manner by this grid of steel tube couplings. Four-channel or multi-channel tubes or rolled profiles can also be used for this purpose, as long as they absorb the shear forces as reliable spacers or effectively prevent shear movements between the composite layers 1, 4. Depending upon the slab design, the dimensions of the aforementioned shear connectors 9 are usually between 200 mm and 350 mm in their length/height and between 50 mm and 150 mm in diameter or across their diagonal. The shear connectors 9 protrude at the top into the concrete layer 4, into which they are concreted. They protrude at the bottom into the wood layer 1. For this purpose, the shear connectors 9 are each inserted, glued, or embedded directly into a recess 30 in the wood layer 1. Alternatively, they can also be inserted indirectly, e.g., by welding them in a steel holder, wherein the steel holder then is glued or embedded into a recess 30 in the wood layer 1. In a variant that is environmentally friendly, because it is free of mortar and adhesives, an internal thread is milled into the wood layer 1 for each steel tube 9 to be used, in order to screw in a steel tube 9 with an end-side external thread. Depending upon the slab span and its payloads, usually between three and six steel pipes per m2 are installed in a distributed manner corresponding to the shear flow.
Towards the top, the slab terminates with the reinforced concrete upper slab of concrete layer 4 and upper portion of the internal bearing means 8. The reinforcement 15 of the concrete layer 4 is extended with a bell butt joint 14 via a connection reinforcement 12 into the region of the internal bearing means 8. For the connection reinforcement 12, bent reinforcement rods are used here. A tensile reinforcement 10 and a pressure reinforcement 11, and a stirrup reinforcement 13 in the internal bearing means 8 as a typical bearing means reinforcement 42, are also shown schematically. A screed/subslab 23 underlaid with impact sound insulation 22 usually goes over the concrete upper slab. Optionally, a slab covering follows at the top on the screed 23. A slab constructed in this way including slab coverings on top of it can be realized with a total thickness of between 350 mm and 450 mm. In this way, it has a slim/thinner design than conventional planar wood-concrete composite slabs of the same load-bearing capacity, in which both the concrete layer and the wood layer have to be designed to be substantially stronger/thicker. For multi-story construction—in particular, high-rise construction—this has a decisive effect on the utilization of the building. At a predetermined building height of, for example, 80 meters, the slab according to the invention can easily achieve one to two stories more than with conventional wood-concrete composite slabs.
b shows a cross-section through the layer construction of the wood-concrete composite slab according to the invention with an alternative embodiment of the internal bearing means 8. In the present case, said bearing means is designed with a steel beam 20 in a modified H-profile form and extends over its length on both sides perpendicular to the sheet plane of
The concept of the bearing means 8 embedded within the slab and interrupting its layer construction offers a space-optimized and at the same time highly efficient bending reinforcement. Under the best possible use of the intermediate space, which the slab statically increases, it is flexurally stiffened with minimal weight input. The insulating material that loads the intermediate space is comparatively lightweight, while one or more internal bearing means 8, as required, are used at the location at which the reinforcement acts most effectively. The internal bearing means 8 run, so to speak, as highly effective “reinforcing ribs” through the slab, regardless of spatial architectural peculiarities, which would have to be taken into consideration for the arrangement of conventional bearing means. Thanks to the very targeted reinforcement, the rigidity and load-bearing capacity of the slab can be decisively increased, with comparatively low use of steel and concrete. The proportion by weight of an optimized wood-concrete composite slab according to the invention, which is allocated to the internal bearing means 8, is only approximately 10% of the slab weight or even less. The weight savings compared to a comparable concrete slab is about 30% with the slab according to the invention, which is considerable. A 50% extension of the span of the wood-concrete composite slab according to the invention to a total length of 9 m, with an increase in weight of the slab equal to or even less than 10%, or even 5-7%, can easily be realized.
Because, with this slab construction, compared to planar wood-concrete composite slabs according to the prior art, a larger spanned dimension can be achieved with a comparatively substantially lower inherent weight, this opens up possibilities for a slab conceptualization of increased area coverage up to inter-story coverage. Specifically, in the case of such slab planning, it is possible to save on load-bearing components which extend through spaces—primarily load-bearing walls—which permanently fix the geometry of a slab plan. The slab system according to the invention thus offers a large repurposing potential for a building, which takes into account the ever faster changing usage needs. Apart from economic efficiency, it has a very positive effect on the sustainability balance of a building, if it can be used in many ways over time without a large amount of remodeling.
It goes without saying that the advantages offered by this slab system are becoming even more important in large-sized buildings. However—especially in large buildings with different building parts and/or numerous separate use units—typically for residential or office purposes—there is another reason—apart from static problems—to install the wood-concrete composite slabs spanning such units with a planar wood element. This is due to sound protection, on which high demands are placed for the non-industrial use of a building. In principle, the higher the standard of an apartment building, the higher the sound protection requirements also are.
Consequently, lightweight components are better than heavy ones for exciting oscillations and transmitting sound. Planar wood-concrete composite slabs with a lightweight wood layer 1 exposed to the room interior, which thus propagates sound well, thus have a difficult starting position. Therefore, in conventional wood-concrete composite slabs, the concrete layer 4 is often made thicker than would actually be necessary statically. For the slab according to the invention, the sound protection means an even greater challenge, because the slab achieves the same static aim with even lower weight, and because the comparatively lightweight wood layer 1 is also still at a distance from the concrete layer 4 and can thus oscillate quasi-independently.
In one embodiment of the slab according to the invention, this problem is addressed by the intermediate layer 3 being filled with at least two layers, i.e., multi-layered, with different insulating materials. For this purpose, the insulating layer 3 has a lower layer 3a with comparatively heavy or dense insulating material. In this way, additional mass can be introduced on and over the wood layer 1 in a concentrated manner in order to load it and thus to make it sufficiently unresponsive to vibration. The remaining space of the intermediate layer is filled with a light or less dense insulating material. The quantitative ratio of these insulating materials can be adapted to the respective sound protection regulations, so that very high requirements, such as are typical for a high-end residential construction standard and in single-family houses, can also be met. In this way, slabs that are comprehensive and usable for a variety of spaces and categories of use can be achieved, whereas conventional wood-concrete composite slabs have to break over partition walls of apartments or office units or other separate units of other use or building parts in order to inhibit the transmission of sound.
Therefore, in a preferred variant of the slab according to the invention, a comparatively dense or heavy insulating material is provided, to work together with a less dense or light insulating material. For this purpose, the wood layer 1 spaced apart from the concrete upper slab by an intermediate space is specifically tasked with lowering the susceptibility of the slab to vibration.
A bulk material is eminently suitable as insulating material. For example, concrete granulate made of crushed concrete or mixed granules of crushed concrete and masonry are recommended for the bottom layer 3a. Such granules can be produced 100% from recycled building substance, which is why it is referred to as recycling concrete granulate or recycling mixed granulate. Filling or lean concrete—preferably made of such granules—also comes into consideration as insulating material for the sound-protection-specific loading of the wood layer 1. A lightweight building material proves to be suitable for the insulating material of the upper insulating layer 3b, e.g., in the form of a bulk material, such as, for example, foam glass gravel, which is produced from pure waste glass. Recycled construction material enters into the environmental impact of a building to an, at most, negligible degree, which is why such insulating material is very preferred.
Furthermore, air can also be used expediently as a lightest insulating material in general for the uppermost layer 3a of the at least two-layer insulating layer 3. The concrete layer 4 that comes to rest over a cavity 3b thus formed must then be supported at the bottom on a permanent concrete formwork 2.
Advantageously, the insulating materials of the at least two-layer insulating layer 3 have very different material densities. The wood layer 1 is thereby loaded in a manner all the more concentrated and thus more targeted, while the remaining intermediate space is not of particular consequence. With selection of a comparatively heavy insulating layer made of recycled concrete granulate applied to the upper side of the wood [density: approx. 1.3 to 2.0 t/m3], and over this a significantly lighter insulating layer made of foam glass gravel [density: approx. 0.2 to 0.3 t/m3], the slab according to the invention significantly saves upon intrinsic weight per unit of slab area while meeting sound protection requirements. The difference in the densities or specific weights of the two selected insulating materials is preferably approximately 0.5 to 2 t/m3. The layers 3a, 3b of the insulation are then introduced in a corresponding space ratio in the intermediate space 3, with the heavy layer 3a on the bottom. Very good values for the acoustic separation of spatial units and stories result when there is a contact pressure of the heavy insulating material of between about 0.7 and 1.4 kN per m2 of slab area and of between about 0.1 and 0.4 kN per m2 of slab area for the lightweight insulating material. A contact pressure of approximately 0.9 kN per m2 of slab area for the heavy insulating material and of approximately 0.25 kN per m2 of slab area for the lightweight insulating material offers a good slab weight/acoustics ratio, depending upon the specific circumstances. In any case, the space filled in by the multi-layer insulating layer 3 has an effect on the weight balance of the slab such that it still fulfills the task of an increased span, yet with minimal weight increase, and thereby achieves high sound insulation values. With its sound-protection specific loading, it can individually meet the respective specifications for the sound insulating mass.
As shown in
A further key to increasing the rigidity and load-bearing capacity of a wood-concrete composite slab consists in the connection of wooden panels combining to form a planar wood element 1. While the concrete upper slab together with its reinforcement 15 is always designed for two-axis support, the wood layer 1—at least according to the prior art—bears the slab as a whole only in one direction. It is indeed the case that the wood-based materials used in wood-concrete composite slabs are usually layered crosswise. Wooden panels made of wood materials layered in such dimensions can thus be load-bearing on two axes. In practice, however, the wood layer 1 of a slab with typical spans usually cannot be produced as a single, continuously veneered panel. Rather, this wood layer 1 is then composed of a plurality of wooden panels, wherein each slab element consists, for reasons of simplicity, of a single veneered wooden panel and the concrete upper slab 4 situated over it or the composite layers 3, 4. However, in order for a large-area wood layer 1 formed by a plurality of subsequent slab element wooden panels to now be able to bear loads continuously on two axes, a tensile force connection of the individual wooden panels is required. In one embodiment, the wood-concrete composite slab according to the invention therefore provides an intimate tensioning of wooden panels load-bearing on two axes. Overall, a very high load-bearing capacity of the slab can thus be achieved without additional weight—especially because the weight of the connecting elements or tensioning means is negligible.
In a preferred embodiment of the wood-concrete composite slab, the latter includes at least two abutting wooden panels, which are tensioned against one another by tensile force with the connection systems presented below. For this purpose, at least one recess 24 is cut or milled out in each case in the wooden panels—leaving intact their undersides above the same—in such a way that, first, they form at least one box-shaped space for accommodating a tensioning means 26a, 26b, 26c, and, secondly, these recesses 24, in the abutting position of the panels, form a continuous recess 25 or a passage spanning across the wooden panels. Behind their rearmost box-shaped space 24, the wooden panels are in each case intact, i.e., they are not drilled, screwed, etc., for this purpose, and there form rear intact material 29 that can be used there in another way. This creates favorable space conditions in the wood layer 1. Primarily during the attachment of shear connecting means 6, whether steel pipes, adhesive, or other wood-concrete connecting elements 6 introduced into grooves or channels 7 of the wood layer 1, it proves to be advantageous to be able to use the wood layer 1 in as comprehensively intact a state as possible for this purpose. The end face 28b of the rear intact material 29 of the wooden panel can also remain free in any case of anchoring for the tensioning means 26a, 26b, 26c—for example, also by adhesives. The tensioning means 26a, 26b, 26c of the connection system is inserted and mounted in the passage formed by the recesses 24 in the abutting layer. The tensioning means 26a, 26b, 26c is in each case anchored at the end in the rearmost box-shaped space 24, 24a of the wooden panel, so that, when the tensioning means 26a, 26b, 26c is subjected to tensile stress, the wooden panels anchored thereto are pulled against one another and thus tensioned together. Tensile forces can be effectively conveyed through a connection formed from at least two wooden panels pressed together in this way. This creates the two-axis load-bearing capacity of the wooden panels thus connected to a continuous planar wood element 1. A plurality of such recesses 24 is typically arranged at regular intervals along the abutment axis in the wooden panels.
The wooden panels advantageously have identically dimensioned and arranged recesses 24. Then, wooden panels having the same recesses 24 at the same location can be prefabricated, so that, when a connection is produced, there is generally no need to pay attention to a specific side. Thus, each prefabricated wooden panel can be located on the near side or on the remote side of the abutment axis. A recess 24 can also be formed from a plurality of smaller box-shaped spaces 24a, 24c and their continuous connections 24b, as will also be presented later. In a preferred variant of the connection system, the tensioning means 26a, 26b, 26c need to be inserted only loosely into the recesses 24. For the tensioning, the tensioning means 26a, 26b, 26c then does not need to be either screwed, doweled, glued, or otherwise secured to the wooden panels by engagement with the wood. Rather, the wooden panels can be left intact except for the recesses 24, which are required for the tensioning. This variant is therefore particularly simple to realize quickly and, especially, extremely easy to install. In the event of faults when mounting the tensioning means 26a, 26b, 26c, the wood cannot be irreversibly damaged. In a further preferred embodiment, the components 26a, 26b, 26c of the tensioning means are joined together to form a symmetrical arrangement, which further simplifies the connection system.
However, how the positive locking of the wooden panels in the abutting layer is formed in detail is irrelevant. In a tongue-and-groove design, an end face of the wooden panel is advantageously provided with a tongue which tapers at an acute angle up to an obtuse angle, and the end face of the other wooden panel is provided with a groove which correspondingly narrows in the depth, so that the wooden panels can be pushed well against one another and are then aligned with one another in an accurately fitting manner. Otherwise, the end faces of the wooden panels to be tensioned can also be designed flat and join together to form a butt joint. All of the embodiments of the connection system presented here can be achieved on wood-concrete composite slabs having a planar wood element 1 with or without insulating layer 3, and thus also on wood-concrete composite slabs according to the prior art.
A specific embodiment with a symmetrical tensioning arrangement is explained on the basis of the wooden panel longitudinal section according to
In
With a further rotation of the sleeve 26c in the fixed location, a strong tensioning of the two wooden panels is achieved, as shown in
A tensioning lock with tensioning lever 26c, as shown in
It will be understood that the present figures are only schematic representations. In the real case, the front intact material 27, against which the anchorings 26a apply pressure directly, is designed to be very much longer or deeper, e.g., 0.2 to 0.5 m long or more, and thus dimensioned to be far longer than the tensioning blocks 26a. The contrasting connection system thus engages over a long or deep range of the wooden panels and withstands a strong tensioning. Depending upon the length or articulation of the tensioning arm 26b, it can also be guided through a hollow channel 24b, which is bored through the front intact material 27, in order to grip against the tensioning block 26a of the adjacent abutting panel.
In an alternative embodiment of the tensioning fastener, the tensioning blocks 26a are each fixedly connected—for example, glued or, as in the example according to
In a further variant, a tensioning of the wooden panels can be realized by means of a tensioning wedge 26c and a counter-wedge 26a, as shown in
With the production of the wood-concrete composite slabs according to the invention, a high degree of industrial prefabrication can be achieved, because the slab can be prefabricated in a modular design and then be assembled in place at the construction site. Above all, this increases construction and assembly efficiency during the production of slabs with large spanned dimensions. Such a method for producing the slab according to the invention is described in detail below.
For a single slab module, the bottommost slab layer—the wood layer 1—is first processed. This is typically veneered as a single seamless wooden panel. At the location of the shear connectors 9 to be inserted, the recesses 30 explained at the outset were cut or milled into the wood layer 1, as can be seen in
In
In
In order for the slab module to be lifted by a crane after its completion, an anchoring of the load-handling attachment 44 in the wood layer 1 is advantageously applied. In the case of lifting belts 44, tensioning blocks—preferably slightly chamfered—that are anchored in the wood layer 1, for example, and tension the belts 44 with the surface of the wood layer 1 are suitable. If an anchoring of load-handling attachments 44 in the slab element is dispensed with, the finished element can instead be raised, for example, using the same wraparound lifting belts.
d shows the next method step, in which the insulating material for constructing the insulating layer 3 is filled in or poured in, etc., over the wood layer 1. In the present embodiment, cellulose fibers are blown in as insulating material, whereby they form a compact mass. The cellulose fibers, which can be seen on both sides along the module, here cover the shear connectors 9 protruding from the insulating layer 3. The film 32 was laid in the formwork 31 such that it can surround the insulating layer 3 over its edge regions. A multi-layer insulating layer 3 is also filled or poured, blown in, etc., in this way—preferably with a separating film 36 between the individual material layers. For a two-layer insulating layer 3, for example, a lower layer of concrete granulate and, above this, a lighter layer of foam glass gravel—preferably in a ratio of their heights of between 1:1 and 1:4 from heavier to lighter insulating layers—are suitable as insulating layers. As shown in
After the insulating layer 3 has been completely applied, the flaps of the film 32 are folded inwards so that the insulating layer 3 is surrounded by the film 32 all around its side surfaces. In addition, a layer release film 36 is placed over the upper insulating layer so that the fresh concrete to be introduced subsequently does not infiltrate the insulating layer 3. Openings are cut into the separating film 36, from which openings the upper ends of the shear connectors 9 can exit, and, in the case of anchored load-handling attachments 44, can exit said openings in guides 45, as can be seen in
The concreting process is shown in
g shows two such slab modules on supports 38, as they are typically stacked for transport. The modules are created in a road-transportable size so that they can be moved to the construction site and can be assembled there to form a wood-concrete composite slab. It can be seen how the insulating layer 3 is surrounded by the film 32 all around its side surfaces and is thus retained. It can be seen that projections of the wood layer 1 of the modules that protrude below the composite are also formed, which form open surfaces 35 at the top. These are filled with fresh concrete poured in place, as will be explained below.
h shows how a single slab module is raised on the lifting belts 44 with a crane device in order to place it in the position predetermined for it. Provided as a support/as supports is/are either vertically installed vertical components of the support structure, such as columns 18 or load-bearing walls, and/or temporary slab supports—for example, in the form of braces. These are removed again after the slab has been completely created. In the module shown, recesses 39 are arranged in both longitudinal sides at regular intervals, viz., where placeholders 33 were previously located. Accordingly, these locations are free of concrete, or, above the wood recesses 24c, are free of insulating material and concrete. Thanks to the excluded recesses 39, this module can be frictionally connected to an adjacent module on each longitudinal side. It is understood that modules to be laid end-to-end do not have any recesses 39 at their end sides. Depending upon the intended frictional connection, the module sides can be provided with such recesses 39, for one-, two-, three-, or four-sided tensioning of the corresponding module with adjacent elements.
In
The bearing means reinforcement 42 is installed in these initially free intermediate spaces 41. An image as shown in
The intermediate spaces 41, which have been completely reinforced, are filled with concrete 48 and smoothed—the recesses 40 likewise, as is done in particular in
In any case, the modular production method of the slab according to the invention represents an innovative, time-saving, and cost-effective method. Due to the high degree of prefabrication, these advantages result, whereby a large-area composite slab can be assembled very efficiently. The internal bearing means 8 were created exclusively on-site here, which, however, will not always be the case. In the case of embodiments of the internal bearing means 8 which project towards the bottom, it proves to be expedient to use prefabricated bearing means components 49. Only the final casting of the bearing means 8 remains to be carried out in cast-in-place concrete 48, as explained later.
In other embodiments of the slab according to the invention without internal bearing means 8, the method steps associated therewith are simply omitted. For example, in one variant, the wood-concrete composite slab according to the invention can be produced in a modular manner from at least two slab modules as a composite slab that is highly sound-protected, but free of bearing means. For their layer construction, from bottom to top, first, the wood layer 1 is in each case produced, including the shear connectors 9 anchored therein with their lower ends. The insulating layer 3 is then formed with at least two layers 3a, 3b, in that a comparatively denser insulating material is introduced for the lower layer 3a, in order to introduce concentrated mass on and over the wood layer 1, with which it is loaded and consequently vibration-resistant. A comparatively less dense insulating material is introduced for the at least one upper layer 3b. Finally, the concrete layer 4 is also applied with its reinforcement 15, so that the shear connectors 9, which penetrate the insulating layer 3, are anchored with their upper ends in the concrete layer 4. Because in this embodiment the modules are not frictionally connected via an internal bearing means 8, recesses 39 are provided in the concrete layer 4 of at least one module, from which recesses the reinforcement 15 exits in order to be frictionally connected to the reinforcement 15 of the adjacent concrete layer 4. These recesses 39 are then also concreted. It goes without saying that, accordingly, the wood layers 1 of the modules can also be frictionally tensioned against one another. Recesses 39 are then not provided solely in the concrete layer 4, but also in the insulating layer 3, so that the wood layers 1 to be tensioned are accessible from above for their tensioning. The completely created slab module is then laid in the position predetermined for it on one or more supports and is connected to the at least second slab module as described, and the recesses 39 are concreted. The production method for a wood-concrete composite slab which is acoustically optimized in this way is characterized by high construction and assembly efficiency. A slab with large spans can be created in principle in few steps by such modules.
Regardless of their disadvantages, conventional wood-concrete composite slabs also offer good load-bearing reliability. For the following considerations, a distinction is made between the normal case and the case of fire. For the normal case, a regular building operation is assumed, with its different combinations of main, additional, and special loads measured as to the probabilities of their occurrence, their duration, etc. With the dimensions of conventional wood-concrete composite slabs, in normal cases, comfortable static reserves are achieved which are sufficient even in the event of a fire if the combustible wood layer 1 is impaired. On the one hand, such wood-concrete composite slabs are of benefit in that they are mostly designed from softwoods such as spruce wood and therefore have to have a considerable thickness for reasons of statics. For this reason alone, these wood layers 1 will not fail immediately in the event of a fire. In addition, wood is decomposed during the combustion process with the formation of charcoal and flammable gases, wherein the carbon layer thus formed forms a very good insulator due to the significantly lower thermal conductivity compared to wood. The inner wood is thus protected for a long time from the effect of heat, so that a thick wood layer 1 still provides a sufficient static contribution even in the event of a fire. However, a slender slab system results in a disadvantage here.
First of all, sufficient fire protection requires that the support structure of a building remain safe against collapse at least as long as is necessary for its complete evacuation. The evacuation duration is calculated according to the building structure—in particular, the design and dimensioning of the escape routes—and is all the longer as the number of stories in a building increases. In addition, components are classified in terms of fire protection—usually according to a load-bearing and/or fire-compartment-forming function. A distinction is also made between linear and planar components. In view of this, the building is then fitted with higher or deeper supports. Only because the wood layer 1 of a wood-concrete composite slab is a combustible planar, load-bearing component is it often criticized as such in terms of fire-protection technology—even though its static performance would basically be sufficient even in the event of afire. This can usually be remedied by elaborate measures in escape route planning and dimensioning and/or a fire-resistant cladding of the wood layer with, for example, gypsum board panels, etc. The result of this is that, precisely in buildings which are regularly covered by high fire protection requirements due to their position, number of stories, and extension, the use of a wood-concrete composite slab with a planar wood element is not appropriate or does not pay off, despite significant advantages.
However, the slab system according to the invention can also be used to tap into such previously unused fields of application. The circumstance can be used that the number of occupants in a building tends towards zero during the evacuation. Accordingly, a support structure affected by fire has to be able to bear only around 50-60% of the maximum load, and also not continuously, but only until evacuation is complete. The wood-concrete composite slab according to the invention can satisfy this condition thanks to its internal bearing means concept, in such a way that the supporting wood layer 1 is not subject to the requirements of a planar, load-bearing component; the non-combustible slab support structure or the residual support structure made of a concrete layer 4 and internal bearing means 8 can completely compensate for the absence of the combustible wood layer 1, so that the wood layer 1 does not have to make a static contribution for the critical period of time. Whereas, in the event of a fire, a conventional planar wood-concrete composite slab, i.e., a load-bearing planar component which as a whole is indispensable, would have been damaged, the wood-concrete composite slab according to the invention would only involve a component that, by comparison, is statically expendable anyway. This leads in particular to the fact that the wood layer 1 can remain unclad and thus can remain visible and distinctive despite requirements for planar load-bearing components. An exception is constituted by escape routes with special requirements beyond the static expendability. In any case, however, the internal bearing means 8 create advantageous conditions, so that in principle fewer or lower fire protection measures have to be provided for a building.
Only in the event of a fire, if the wood layer 1 is fire-damaged, e.g., due to failure of a sprinkler system 34, must it be possible for the horizontal load absorption and transfer to the vertical supports 18 to be distributed to all bearing means 8a, 8b of the slab. They then all form indispensable components of the residual support structure. It is now decisive that the slab, with the inclusion of all internal bearing means 8a, 8b, is divided into numerous smaller slab areas, because, according to this static analysis, the secondary internal bearing means 8b also act upon the load absorption or the load transfer. Accordingly, new main and secondary support directions of the slab also result in relation to these smaller slab areas, which for reasons of clarity are not specifically shown here. The slab areas supported on the active bearing means 8a, 8b are consequently less, so that the comparatively thin concrete layer 4 can span the story for the relevant evacuation duration in this cassette slab structure of the slab and be safe against collapse. The wood layer 1, or at least the relevant part thereof at risk of fire, can be regarded as static, like a cladding, during this period. Therefore, the wood layer 1 also does not need to be covered in a fire-resistant manner, and instead offers an aesthetic, continuous, and thus uninterrupted, slab soffit in the interior of the story. Of course, the wood layer 1 can nevertheless be plastered on the interior side, or even only in some places if this is desirable, e.g., with regard to the particular aesthetics or if such is generally prescribed—for example, along escape routes. In the present embodiment, the building core 17 also forms the exit route at the same time. In any case, thanks to such an internal bearing means concept with internal bearing means 8b, which normally are statically superfluous, the fire protection requirements for a building can be significantly reduced.
In other embodiments of the slabs according to the invention, internal bearing means 8 can also be conceptualized as a makeshift, static remedy in the event of a fire. The reverse case, with one or more bearing means 8 only as primary bearing means 8, or only as primary internal bearing means 8, is also conceivable if this can be implemented in terms of fire protection. In any case, the rigidity/mass ratio of the slab is optimized with integration of internal bearing means 8 into the support structure to be loaded in a regular manner, its weight is reduced, its height is minimized, and the number of stories in the building that can be realized is maximized, as has already been explained at the outset. The proportion by weight of an optimized wood-concrete composite slab which is dispensed with on the internal bearing means 8, 8a, 8b is only approximately 10% of the slab weight, or even less. The gain in flexural rigidity and associated advantages exceeds this weight amount in several respects. It is therefore advisable to statically distribute the supported load even of the regular building operation on internal bearing means 8, 8a, i.e., to design at least a portion of the internal bearing means 8a as a component of the primary support structure.
The slab plan according to
In some cases, it is advantageous to be able to increase the cross-sections of the internal bearing means, i.e., beyond the height of the slab layer composite, in order to achieve a particularly high bending reinforcement. Possibilities for such an upper or lower projection of an internal bearing means 8 from the composite slab are presented below.
The support configuration according to
From an architectural point of view, the lower projection of the internal bearing means 8 can be perceived as optically dominant and accordingly be undesirable. A remedy is provided here by a capital construction as shown in cross-section in
b shows a view through the section line A-A in
In the slab composite according to
On the basis of the projecting variants of the internal bearing means 8, it is shown how the production method of the slab described at the outset can be adapted or modified, for example. The slab manufacturing method can be summarized as follows for both variants of the bearing means production—all on-site or partially prefabricated and partially on-site: the slab according to the invention is assembled from at least two slab modules, wherein the slab modules are created with their layer construction in each case, so that, from bottom to top, the wood layer 1 is produced first with the shear connectors 9 anchored therein with their lower ends. The insulating layer is then created. Preferably, it is formed with at least two insulating material layers 3a, 3b in that a comparatively denser insulating material is introduced for the lower layer 3a in order to introduce concentrated mass on and over the wood layer 1 in order to load it and thus make it vibration-resistant, while a comparatively less dense insulating material is introduced for the at least one upper layer 3b. The shear connectors 9 pass through the insulating layer 3. Finally, the concrete layer 4 is produced with its reinforcement 15, wherein the shear connectors 9 are anchored therein with their upper ends. After this, the slab modules are laid in the position predetermined for them on one or more supports. For this purpose, the two slab modules either
Alternatively, the slab modules are supported on
A bearing means reinforcement 42 is inserted in the intermediate space 41 formed according to i. or ii. and connected to a reinforcement 15 of the adjacent concrete layers 4 of the slab modules. The intermediate space 41 is then filled with concrete 48, so that, with curing thereof, a bearing means 8 which is embedded within the composite slab and which is possibly projecting from the layer composite at the top and/or bottom is completely created. For the upper projection of an internal bearing means 8, an upwardly extending concrete formwork adjoining the corresponding intermediate space 41 is applied at the top, and the space 41 expanded as a result is filled with concrete 48. After the concrete 48 has cured, the concrete formwork is removed again, whereby a bearing means 8 projecting above is completely created.
The various embodiments prove that an internal bearing means 8 can be designed in a great variety of ways, sometimes through aesthetically designed projection shapes. Internal bearing means 8 projecting from the slab layer composite enable an even greater flexibility in the slab plan design, because the vertical supports due to their very large bending reinforcement do not have to be arranged as densely. On the other hand, it can also be desirable to let all internal bearing means 8 disappear in the slab. In a combined variant, for example, only the primary internal bearing means 8a can also project out, whereas the secondary bearing means 8b, which, except when a fire is involved, make a negligible static contribution anyway, are completely integrated into the slab. They then also have no optical effect as pure makeshift elements, whereas this is tolerated in the primary internal bearing means 8. The decision as to where which internal bearing means 8 are to project out of the slab can also be architecturally motivated and, statically, sufficiently implemented. Finally, each building has its own type, which is why one or the other embodiment variant is accordingly also better suited. In any case, the internal bearing means 8 can be selected individually and, if necessary, different embodiments can be combined with one another and can also be supplemented as desired with conventional bearing means that are not installed in the slab.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21203049.8 | Oct 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/078753 | 10/16/2022 | WO |
