|
(11) | EP 1 132 538 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 158(3) EPC |
|
|
|
|
|||||||||||||||||||
| (54) | PREFABRICATED SELF-SUPPORTING PLATE MADE OF POLYSTYRENE AND CONCRETE |
| (57) Pre-fabricated plate, self-supporting along its entire length, comprising two concrete
ribs with a double T shape and three polystyrene arches of the same thickness as the
ribs, which together with the on-site addition of a compression layer conform a floor.
As the ribs have this double T shape and as said ribs are concreted against the arches,
the unit is assembled and allows walking on the arches during construction with full
safety. As an alternative the ends of the ribs may be provided with extensions having
a lower cope in order to absorb the thickness of the plank of the semi-prefabricated
beams of the scrap box type with a concrete plate, on which they will rest, thereby
obtaining a smooth prefabricated structure on which plaster may be directly applied,
without requiring a false ceiling. |
OBJECT OF THE INVENTION.
[0001] The present invention relates to a prefabricated plate based on arches and ribs with a double-T shape made of reinforced or pre-stressed concrete. Because of the concreting of the ribs machined against the arches, the latter are inserted in the ribs and thus is obtained a prefabricated integral plate.
[0002] These plates and a top mesh, steel for negative moments and a compression layer constitute a floor for construction.
[0003] As an alternative, at the ends of the plate the ribs may have extensions with bottom copes of the same thickness as the prefabricated beams of the plate type or a bottom concrete plank on which it rests, providing a level floor and beams, such that the plasterwork may be applied directly on the underside of the structure, and the beam and the floor cannot be distinguished.
[0004] The main problem is solved by adapting the floors based on prefabricated plates to the "smooth" structures characteristic of floors currently built in Spain and other warm weather countries, which constitutes a further object of the invention. Currently, classic arch and joist structures are the most economical floor structures for countries with a Mediterranean or Tropical climate.
BACKGROUND OF THE INVENTION
[0005] Level joist and arch floors are those used most often, as they are inexpensive as regards materials and labor in prefabrication and on-site assembly. In Scandinavian and Central European countries where temperatures remain low nearly year-round, and rain is frequent, on-site working time must be as short as possible in order to prevent increased labor costs and to reduce the risk of freezing of the concrete poured on-site. Thereby in Northern countries prefabricated floors of the semi-plank type, both pre-stressed or reinforced, or of the pre-stressed honeycomb plank type are frequent and classic joist and arch floors are seldom employed.
[0007] Use of prefabricated pre-planks or honeycomb plates in floor construction implies that joists need a greater thickness than plates and require false ceilings. resulting in a greater cost of the floor as compared to the classic direct plastering of the floor.
[0008] In the market and state of the art one can find a great variety of floors with polystyrene arches and concrete joists, and prefabricated plates misnamed as "self-supporting", as they are simply very rigid..
[0009] We generally tend to describe these systems as self supporting, when in reality they are self supporting for 2 or 3 meters, which is the typical distance of measurements or intermediate supports during the construction of a floor. In order to be self supporting over their entire length, (4 to 7 meters is the typical span of household buildings) with conventional floor thickness, on center distances and loads, it is not enough to state this term: it is necessary to define the technical characteristics required to achieve this, with the deformation limits according to 1/250 standards for an infinite time sag.
[0010] The author of this patent requested a list of the state of the art and in 9 of 200 patents consulted in the search prefabricated plates made of polystyrene, concrete and steel are claimed. From them any engineer experienced in structure calculations can work out that these cannot be self-supporting for lengths between 4 and 7 meters typical of floors. In some of these the plates are said to be lifted manually, in others 6.8 m of plate weigh 60 kg, in others it is stated that the reinforcement provide the self-supporting characteristic of the prefabricate, in others they are described without a compression layer on the site and finally, do not have a compression head to withstand such lengths.
[0011] Naturally, if the thickness and size of the plates consulted are increased considerably the self supporting length is also increased, but the resulting thickness and cost make them uncompetitive against joists and arch for a similar span.
[0012] None of the plates consulted mentioned the possibility of walking on the polystyrene arches. This is because expanded polystyrene is not very strong, and none of the authors conceived that it could bear the weight of a person even overhanging with a safety coefficient of 2 (the minimum required).
[0013] Given the nature of the invention, as it is a very specific technical improvement on the existing invention, in accordance with standard 5.1.b the author considers it convenient to include drawings of the current state of the art, with reference made in this section to define the differences with this patent.
[0014] Figure 13 shows typical floors of joists reinforced with lattices and polystyrene arches, with or without a bottom coating tongue of the joist. These floors are "self-supporting" over approximately 1.5 m due to the lattice, and require a straining piece or buttress until admitting the concrete mixed on-site for these distances. Risk of workers falling due to sliding of the arches on the joist supports or breaking of the arches is high, and therefore in most European countries, including Spain, its use is forbidden without using safety boards or placing a fillet under.
[0015] Figure 14 shows another two typical floors, with a bottom concrete plate which bears a stiffening mesh, stiffening or "set supporting" lattices over 1.5 m (therefore requiring on-site straining pieces and lightened polystyrene blocks or arches. Even in the lower drawing, ribs are concreted in-factory, increasing the "self-supporting" capacity to 3 m, with normal plate thickness of 22 to 28 cm. The lattice must project vertically in order to ensure the grade or union stresses between the two concretes. In this case there is no risk for the worker as the reinforced concrete bottom plate prevents the fall. These are widely used in Germany and Belgium, among other countries. Likewise, they have the disadvantage of being more expensive than the traditional arch and joist structures and in that their cutting on-site is laborious, as the entire plank must be cut.
[0016] Figure 15 shows another type used for covers, in which the polystyrene covers the entire lower part and perfectly insulates the floor. This model is completely self supporting along its entire length and is generally used without a compression layer on-site. When constructed with rib center distances from 50 to 80 cm, a top mesh is required as well as a 4 cm thickness plank, as otherwise it would not be very resistant and cracks or breaks would result. In this model safety is good as the weight of the worker is supported by the concrete, but cutting on-site is expensive and the weight is high.
[0017] Figure 16 shows a variation of a honeycomb plate where the honeycombs are made of expanded polystyrene. It is self supporting over its entire length but is not cut well on-site, it is expensive, heavy and has thermal bridges at its ribs.
[0018] The model of figure 17, known as PLASBU, makes the polystyrene arch rigid by adding a small concrete bottom rib with a lattice, thus making it self supporting over 2 m, and making it more expensive than the traditional one. It insulates well and is easy to cut, although it requires straining labor and on-site assembly. If one walks far from the concrete rib the arch may return and the worker may fall.
[0019] Figure 18 shows a model of a joist reinforced with a lattice, concreted inside a box of the polystyrene arch. It is not self supporting for more than 1.5 m (therefore requiring on-site straining pieces, making it impossible to walk on, but it provides a good insulation and is easily cut.
[0020] The right hand side figure of Figure 19 shows a joist model (as described by its author) which consists of a joist coated in polystyrene, intending it to be lightweight as it is a joist which may be lifted manually, although it is not self-supporting from 4 to 7 m as any engineer experienced in structure calculations could deduce. The patent does not mention how to walk on the polystyrene as it is simply an insulating coating and not a prefabricated plate as such, with a large format. Union to the concrete mixed on-site is obtained by steel seaming, and is thus expensive. The system is also expensive as it requires placing many joists next to each other and lifting each one manually and individually.
[0021] Figure 19, on the right, shows the same type of joist coated in polystyrene with a different type of lattice which is mounted on-site in the same manner, next to each other.
[0022] In another patent (figure 20) the same part is shown, here larger, with the size of a conventional 50 or 60 cm arch but with a single rib per prefabricated element. The same incorporates a resistant plate in order to attach and stiffen the arches, and is used without a compression layer. As can be seen, the author does not provide the arches with a resistance for persons, but instead provides only a very low resistance, also to fire. The shape of the rib is not defined and something resembling a simple T is depicted.
[0023] Figure 21 shows a further variant of a prefabricated plate which comprises several ribs or joists next to each other and integrated in a continuous polystyrene arch. In this patent it is stated that it is a lost form and it is not claimed or described as self supporting along part or all of its length, nor is the shape of the rib required to make it so. As mentioned above, it can be self supporting if the scale is increased but they are not valid with conventional household building thickness.
[0024] Figure 22 shows another prefabricated self-supporting plate, at most over 2 or 3 m for similar thickness as the traditional floor which it replaces. As mentioned by the author the plate 6.8 m long weighs 60 kg, so that it cannot be self supporting over 4 to 7 m.
[0025] The author stated that the self supporting capacity is due to the lattice reinforcements of the commercial DAVUM, KAISER, FILIGRANE, DATEU, BAUSTA-OMNIA types among others, that is. conventional reinforced joist lattices. Even if the lattice diameter is increased they cannot be made self supporting over 4 to 7 m unless the thickness is increased much beyond the traditional floor which they replace.
[0026] Stability is ensured as there are two ribs per plate, although rib on-center distances are 30 to 45 cm. The cost of this plate is greater than that of the joist and arch floor which it replaces. The patent also does not mention doing anything about the safety of walking on the polystyrene. In fact, we can see in figure 23 that when walking on the edge there is a risk of falling if the rib concrete is not sufficiently vibrated.
[0027] Figure 24 explains with the aid of a drawing the need for concrete ribs to have double flanges as even if the concrete is not vibrated, when exerting a force on the arch the crack will continue until reaching the lower part of the top flange, the union will begin to operate under shearing, which prevents supporting 100 kg on the overhang without breaking for polystyrene densities of 20 kg/m3 and a safety coefficient of 2.
[0028] Before continuing it must be pointed out that concrete vibration and setting age greatly affect the adhesion of the polystyrene and the concrete, and thus we cannot ensure the safety of walking on the plate in these conditions. It is therefore necessary to provide a system which, regardless of vibration, always ensures the insertion of the arch in the rib.
[0029] This point is guaranteed by pinching the rib with a double-T shape on the arch. This way the overhang moment will be absorbed by the shear between the two contact surfaces. The concrete sets in the same shape as the polystyrene surface. which is not regular and is even porous, so that when operating under shearing the polystyrene does not slide suitably, such as when the load is perpendicular to the union surface or when the concrete is insufficiently vibrated.
[0030] Figure 25 defines the overhang and thickness for an effective insertion of low density polystyrene (10 kg/m3), which is less costly, with the relation with each other in order not to break as follows:
where the weight is in kilograms and the overhang V and thickness H in centimeters. As can be seen overhang V is determined by the edge of the lower flange and thickness H is measured from the bottom of the top flange to the bottom of the arch. This theoretical-experimental formula includes a safety coefficient of 2. In a first approximation, this relation leads to an overhang which is smaller than the thickness.
[0031] Figure 26 shows that due to the double-T arrangement the integral union between the two ribs is ensured both for negative and positive moments, loads in stacking and elevation and transport on-site.
[0032] Figure 27 shows that working the section with negative moments near the floor or plate supports requires a compression head with the bottom T implying that for the same thickness and negative moment, less steel is required than for the bottom case without a T, as the center of mass of the stressed concrete area is greater in one case and lower in the former case.
[0033] In general, none of the patents related by this author is provided with mutually independent arches as they are always joined by the bottom of the joists, or by the polystyrene, or by a plate of a strong material.
[0034] Lattices are employed to join concrete, not claiming any top finish of the rib. In most patents the lattices are employed likewise, as they arc self supporting to a length of 1.5 to 3 m.
[0035] No known procedure claims or mentions the fact that it is possible to walk on the polystyrene safely, as certain conditions must be met for this which have not been determined by them as it is hard to believe that a low density polystyrene (10 kg/cm3 to 20 kg/cm3), the same as used for insulation, with flexotensile strength between 0.5 to 0.8 kg/cm2, could enable a person to walk on an overhang without breaking it. Naturally, as the density is increased the resistance increases as well, but the price increases more so, making it unviable.
[0036] All patents consulted are centered on claiming thermal or acoustic insulating plates, but none deal with worker safety. Furthermore, all agree in that in order to secure the polystyrene or insulator to the concrete rib so that it does not fall, the lower part of the ribs are provided with a dovetail shape, or the plate or bottom of the ribs are embedded in an insulator or in an arch.
[0037] It must be again remarked that in order to be self supporting, standard L/250 of total sag at infinite time must be complied with, for the same spans, loads, on center distances and thickness as the traditional floor which is to be replaced, for a top head with a T shape and the same rib thickness as that of the arches, that is without a bottom coating of polystyrene or minimum.
DESCRIPTION OF THE INVENTION
[0039] The invention object of the present memory relates to a type of semi-fabricated plate which includes all advantages of prefabrication and thereby reduced construction times and costs, further providing a solution for support of the prefabricated joists which allows leaving the bottom part of the structure fully smooth and ready to receive the direct plasterwork at a good price.
[0040] This plate may be used resting on classic unidirectional smooth beam forms (used to support beams and floor joists), on brick walls or combined with TUL type beams consisting of a scrap box with a concrete plate. These beams allow to rest the floor on said plate. thus preventing forming on-site, which is expensive due to the investment required by it.
[0041] Afterwards, in the construction site, by means of displacement of a steel mesh on the top and pouring of at most 4 or 5 cm of concrete on all plates, the floor itself is made. In this manner the operation of all plates is likewise continuous in a transverse sense..
[0042] As the plates are prefabricated the slow on-site placing of heavy arches one by one made of ceramic or concrete is not required.
[0043] Reinforcement for negative moments can be distributed in steel bars of a smaller diameter and distributed on the entire top surface of the plates, so that these are concentrated on top of the ribs.
[0044] The prefabricated plate is between 0.6 and 2.4 m wide, with a typical width of 1.2 m due to transportation and to the weights which can be lifted by cranes used in construction, The rib on-center distance is similar to the traditional values of 60, 70 or 80 cm. The length of the plate depends on the span between structure beams and construction loads. Among the most typical is 22 cm, and adding 4 cm more on-site provides the 26 cm of traditional floors calculated for spans between 3 and 6 m and typical floor loads of 660 kg/m2 total load
[0045] Each prefabricated plate includes two solid concrete ribs of the same thickness as that of the plate, making it rigid and preventing on-site straining pieces. They are therefore self supporting, as with honeycomb plates. These further avoid return, so that the plate rests on 4 points, avoiding bad stacking and providing stability in transportation. The ribs have several shapes, the more typical ones having a double-T shape for each rib.
[0046] The advantage of being self supporting results in a reduced on-site work. It must be again remarked that in order to be fully self supporting, not semi- self supporting, the same thickness as that of the traditional floor which it replaces is required for the same spans and loads. For the self-supporting characteristic to be profitable, only concrete compression heads can be employed, as profitability cannot be achieved with a superior reinforcement such as a compression head because the rib section would have a much lower inertia and cause deformations above those allowed by regulations. Naturally, if the thickness is increased the inertia is increased, even for superior steel, but it is then not more competitive with the thickness of a traditional floor.
[0047] The reason for the top "T" is then that in order to attain self supporting characteristics a superior concrete compression head is required with a width much greater than a simple rib; in turn, this greater width allows by means of the top striated surface contacting the concrete poured on-site, to transmit loads through the grade between the two concretes, including tensions on the negative moment steel; further allowing assembly on insertion by shearing of the lightened arches between ribs. Finally, the greater width provides workers with greater safety, as these will walk on concrete areas and not only on the arches.
[0048] The reason for the bottom T is that where the floor works with negative moments, we have a wider stressed concrete head. saving in negative moment steel as compared to traditional floors with a narrow bottom rib. These lower flanges of the ribs in turn serve to rest and assemble the polystyrene or ceramic arches, preventing their fall, sliding or breakage when a worker walks on them. Their function is to reduce the overhang of the arches, as this is measured from the edge of the bottom flange to the free side edge of the plate. This is the only way in which a safety factor of 2 can be obtained when a person is walking on top, and in which on-center distances between ribs are obtained identical to conventional ones of 60, 70 or 80 cm.
[0049] As they are concreted in factory, adhesion between these parts and the concrete of the ribs is ensured, contrary to classic structures of joists and arches in which the arches are easily released and slide from the joists until the concrete is poured on-site. The bottom T likewise increases the moment of inertia greatly, with a minimal weight, which is important in obtaining the L/250 limit for the total sag at infinite time.
[0050] Plates may have 1, 2, 3 or 4 ribs depending on the taste of the designer and the fabrication widths, and may have protrusions on the flanges of the T's both at the top and bottom to allow better assembly of the arches. For a single rib the section does not require a bearing support as the lower flanges of the double T make it stable. The double T flanges may have any shape and size: triangular, trapezoidal, oval, rectangular among others, and the top and bottom flanges may even be different. Likewise, the arches may have longitudinal grooves to help assembly on the ribs, reducing the flanges or in order to receive the plaster on the bottom side of the plate.
[0051] A further consequence of the double T's is that the cavity which is left between the flanges of two adjacent ribs is smaller than 40 cm, so that a person cannot fall through it even if the polystyrene arches did break, increasing its safety advantage.
[0052] Naturally, steel for withstanding the floor's positive moments is incorporated on the bottom of the ribs from the time of manufacture, and as these are wider at the bottom they have a greater cover and greater space for filling with concrete. Steel for negative moments will be placed on the plate, and will be concealed in the concrete of the compression layer poured on-site. If no compression layer is poured on-site negative steel can be incorporated on the top of the ribs during manufacture.
[0053] Steel to be placed on the prefabricate may be pre-stressed steel, with the resulting savings in construction steel as its higher elastic limit allows to reduce its section considerably.
[0054] Construction of the plate with arches in the factory entails a further advantage, as it is not necessary to use a cast to give the ribs their shape, as the double T shape is obtained with the figure drawn on the polystyrene arches (or of any other material), with the later cast removal not required. At most, if polystyrene arches are used it will be necessary to avoid their floatability by pouring concrete into the ribs with a small bottom tongue of the arch. in order to counteract the concreting pressure, or by a metal frame to walk on top of it. The investment required to make these plates is much smaller than those of other installations of pre-boards or honeycomb plates.
[0055] Among other advantages of the new plate is the possibility of reinforcement with cut steel or seam steel of only the support areas if the calculation requires so, or to increase favorably both the top and bottom compression heads. Increase in the rib width and of its reinforcement due to loads later concentrated in the building is also not a problem as narrower arches are used in order to increase the width of the rib. The change in thickness of the floor is immediate by using arches with a greater or smaller thickness, thus adapting to smaller or greater spans and loads, but which are always equal to those of the traditional floors to be replaced.
[0056] The ends of the ribs can have an salient reinforcement in order to anchor the cutting stress on the support as per current regulations.
[0057] Contrary to honeycomb plates, cutting of a plate is quick along a longitudinal direction and the possibility of cutting the polystyrene arch laterally allows, in factory or on-site, to adapt easily to the widths of the floor surfaces, when these are not multiples of 120 or 60 cm. In the transverse cut it is only necessary to cut the concrete rib and not the top and bottom boards of honeycomb plates, as well as their numerous ribs.
[0058] The main advantage obtained from this new system is also an economical one, as when adding all costs involved in its fabrication and assembly we find that it is lower than for a for a traditional joist and arch floor, hitherto considered the cheapest in the market. Despite employing mainly the polystyrene arch, which is more expensive than the concrete or ceramic one, this is offset by: the new plate not incorporating concrete as a traditional one, not requiring lattices; it substantially reduces the negative moment reinforcement as it has a lower compression head; for a typical thickness of 26 cm it weighs 75 kg/m2 less than a traditional reinforced joist structure and thereby allows to reduce cost in steel in the entire construction; as it is not necessary to place safety planks on-site it saves labor; as it does not require special casts the investment in a fabrication installation is low, etc..
[0059] A further possibility would be to use extruded or molded (with ribs) polystyrene in order to use less polystyrene and thereby reduce the cost of the plates.
[0060] As regards the weight of the finished floor, it is lower than that of a joist and arch floor if polystyrene arches are used, saving a few kg of steel in the calculation. A floor of ceramic joists and arches for a 26 cm width weighs 260 kg/m2, while the new floor weighs 185 kg/m2.
[0061] The weight of the prefabricated plates (for a plate 22 cm thick, 1.2 m wide and 5 m long. typical of household buildings) is on the order of 5043 kg, allowing 750 kg cranes to lift them easily. Transportation is also less costly than for honeycomb plates of similar use and identical to that of joists and arches..
[0062] For each plate two unions between ribs can be provided, which implies separating the arches between 5 and 15 cm (typically 8 cm) at a certain distance from the ends of the plate. In this way the union of the two ribs provides the required stiffness to the prefabricated plate when the arches do not have a double T shape, or when using widths greater than 1.2 m with more than ribs, for transport, stacking or lifting.
[0063] Eventually coffers can be made in the lateral thickness of the plates, made on the arches as far as the rib concrete, and reinforcements anchored to the rib may project out from them. By the on-site opposition of said coffers with the coffers of the adjacent plate and the on-site incorporation of an overlapping reinforcement between the two coffers, when the concrete mix is poured on-site an even better performance is achieved against transverse stresses of the ribs. These coffers also prevent use of a compression layer with mesh on-site, as in this manner the function of the compression layer and the mesh are exchanged in resisting stresses transverse to these connections between plates, saving in concrete, mesh and structure weight. Naturally, the compression head or top T must be increased. These connections may be also performed with tensors housed in the coffers between the plates, providing a rear tension between plates which is very useful when preventing the bottom plaster from cracking between plate junctions.
[0064] One of the most important variations of this new floor system is on the ends of the plates, on the support on the TUL type beams with a concrete plate and scrap box. For it the concrete rib extends overhanging from the plate by 10 to 20 cm with a rectangular section, as here the double T is not required. This vertical rib includes a lower cope of the same thickness as the plate of the beam on which it rests, in order to make its lower part even with the lower surface of the beam. The cavity between the arches and the edge of the beam plate, on the order of 2 to 12 cm, is provided with a small continuous forming plate with stanchions at given intervals, so preventing the filler concrete for the beams and the compression layer from falling between the plates and beam when poured on-site. Likewise, we make this area solid, which is important for the operation of the floor in negative moments.
[0065] If a lower polystyrene coating has been applied on the ribs it is not necessary to place the small forming plate for filling, as barely any thickness is lost in the support and a polystyrene "cover" is enough to fill in the residual cavity and fill it from the bottom when applying plaster, paper or a polystyrene band.
[0066] These rib extensions may also be employed to rest a traditional form or brick walls so that the concrete mixed on-site clamps these punches, providing a better floor structure.
[0067] Fabrication of plates with an angle at the support is performed immediately by cutting the polystyrene arches to the desired angle and in-factory addition of recoverable metal covers for structures, or in the case of salient ribs using angular coffers to make said salient punches. These coffers may also be made of polystyrene, which is easily worked, and will be removed once the rib concrete has set.
[0068] Salient ribs for supporting plates may as an option be provided with a top cope which allows to place the negative moment steel for main beams more easily.
[0069] Naturally, this support system can be applied to all prefabricated polystyrene-concrete plates existing in the present state of the art.
[0070] In all, the arches are interlocked to walk on top of them and to join the set with respect to flexions in both senses during stacking, transport and lifting. It is also ensured that if a rib breaks due to cutting during handling, the central polystyrene anchors this rib to the other during assembly and concreting. without causing accidents. The double T reduces the overhang of the polystyrene so that the joist can be walked on on-site.
DESCRIPTION OF THE DRAWINGS
[0071] These and further characteristics of the invention will become apparent in view of the accompanying drawings, where for purposes of illustration only the following is shown:
Figure 1 shows a section view of the prefabricated plate for unidirectional floors of building structures in the same form as it is manufactured..
Figure 2 shows a section view of a finished floor employing the aforementioned plates in transverse continuity, on which is incorporated a concrete compression layer to give continuity to the floor.
Figure 3 shows a side view of the prefabricated plate with a variable length depending on the construction requirements, in which can be seen the system for end support on Tul type beams with a concrete plate.
Figure 4 shows a perspective view of the plate with one of its ends, revealing the ribs which protrude and rest on the Tul type beam, and on the right showing a plate without a protruding punch and with its top striated area exposed.
Figure 5 shows a side view of the floor formed by two prefabricated plates resting on a Tul type beam with a scrap box and a concrete plate.
Figure 6 shows a top view of two types of prefabricated plates, showing the top surface of the ribs with the width of the flanges and the possible connection between two longitudinal ribs of the plate and another two perpendicular ribs, providing the plate with a greater stiffness regardless of the double or simple T-shape of the ribs and without requiring a continuous lower concrete plate.
Figure 7 shows a sectional view of a plate with unequal trapezoidal flanges.
Figure 8 shows a sectional view of a plate with longitudinal grooves on the two surfaces of the ribs and a polystyrene coating on the bottom of the ribs.
Figure 9 shows a sectional view of a plate with 3 ribs similar to those of the previous figure. albeit narrower.
Figure 10 shows a plan view of the end of a plate finishing in an angle and how to make salient ribs by U-shaped forms, which as in the previous case may be made of polystyrene.
Figure 11 shows a top plan view of a plate with side coffers for transverse connection of plates by stressed steel or a tensor hook.
Figure 12 shows a sectional view of a finished floor showing a rib with a greater width, as well as a beam or a clamp parallel to the floor, with arches of the width required to adapt the exact position of the clamp to the construction requirements.
The remaining figures, 13 to 27, have already been described in the Background section, so that it is not considered necessary to describe them again.
PREFERRED EMBODIMENT OF THE INVENTION.
[0072] In view of the figures, we describe hereunder a preferred embodiment of the invention relating to a plate (1) comprising two concrete ribs (2) and an arch (3) of polystyrene or another material with the same thickness as the ribs, without a lower coating. Inside said ribs is housed the reinforcement (4) required to withstand the negative moments of the floor.
[0073] In industry manufacture of polystyrene arches (3) begins with a low density polystyrene block with typical dimensions of 1.25 m width, 0.50 m height and 4 m long, and using a pantograph the desired arch is drawn with a hot wire and the double T crimp of rib (2) is drawn on it.
[0074] Arches (3) are placed on a mold or sole plate at the distance required by the width of ribs (2) using concrete separators housed at the bottom which provide a correct support and a cover for the positive reinforcement (4).
[0075] Once the arches are placed in the mold and the scrap or inferior steel (4) is inserted, the ends are closed with recoverable forms made of plate or wood. with grooves provided for passage of connection reinforcements (32) and protrusions for leaving a crimp of the grooves in ends (33) of the plate in order to ensure cut-off when resting on smooth beams. Afterwards the concrete of rib (2) is poured in the cavity and it is distributed and vibrated until filling it.
[0076] Afterwards and before the concrete hardens completely, the top surface (11) of ribs (2) is striated in order to ensure the union to the concrete poured on-site corresponding to the compression layer (8).
[0077] In order to prevent the return of arches during concreting and vibrating, two fixed side walls will be placed on the mold separated by the same width as that of the plate, normally 1.2 m.
[0078] In order to prevent floatability, workers shall walk on the arches while they are concreted and vibrated or they will be aided by an auxiliary metal bar, or the arches may have a lower tongue (as in 25) which counteracts the concreting and vibrating pressures.
[0079] Even if an area of the ribs is not correctly vibrated, as the polystyrene walls have an irregular surface with small pores between the polystyrene balls, the concrete adopts this shape and concrete pins even enter such pores, as they work on the surface in shearing and make the concrete slowly break the polystyrene, distributing loads on the entire shearing surface evenly, and thus with strengths of 0.5 to 0.8 kg/cm2 to flexo-tensions, tension or compression of the polystyrene we can add a great surface and therefore a great strength which can support a person with a safety coefficient of 2. Retreating problems will be due to arch breakage, not to separation of the polystyrene-concrete junction, which will not occur without the double T shape. For an arch to break under the aforementioned load the salient must not be greater than the retreat thickness for a conventional floor thickness between 24 and 33 cm.
[0080] In order to form floor (5) on-site, the plates are joined parallel to each other, resting on the prefabricated support beams of the structure, or on its form if they are on-site, or on the support brick walls, and the plate will be completed by placing reinforcement (6) to withstand negative moments and also adding on-site a steel mesh (7) and a thin concrete compression layer (8).
[0081] Ribs (2) of said plates will have a double T shape with bottom flanges (9) required for support and assembly on the bottom of arches (3), reducing the overhang, acting as a compression head when the floor operates under negative moments and increasing inertia with a minimum weight for reducing sagging. At the top of T-shaped ribs (2) flanges (10) allow a top assembly of arches (3), also forming a compression head to withstand negative moments of the plate, placed on-site so that they are self-supporting along their entire length, ensure load transmission between rib (2) and compression layer (8) of the construction through rough surface (11) between the two concretes and reducing the cavity between the ribs in order to prevent a person from falling between them, even when an arch is defective. Said rough surface (11) is made by scraping the surface, as this is the least expensive manner, or by any means available, such as a seam reinforcement, photogravure, etc.
[0082] If the plates are to rest on Tul type beams, ends (12) of the plates are provided with extensions (13) of concrete ribs (2) made with a recoverable form, which by a cope (14) on their bottom allow support on the plates of prefabricated beams (15) of the scrap box type (16) with a concrete plate (17), so that the bottom part (18) of the plates is even with the bottom part of beams (19), thus providing a level floor.
[0083] To prevent concrete from falling between the arches (3) and the plate of beams (17), the plates may be placed continuous (20) resting on stanchions (21) in the construction itself.
[0084] If arches are employed which cannot stiffen the plate by joining the two ribs, as they do not have a double T shape or they are made of a material weaker than polystyrene, each pair of ribs (2) of the plate can be joined by solid fillers with reinforcement (22) at two or more points, thus ensuring the stiffness of the prefabricated plate during handling, lifting, stacking and transport.
[0085] In order to ensure a better union or assembly of arches (3), for a very uniform and non-porous material, to ribs (2)the arches may be manufactured provided with protrusions (23) on the ends of its flanges which force the to arches remain strongly joined to the ribs.
[0086] A further possibility is to make grooves (24) on the sides of the arches (3) inside the ribs. or even on the flanges, in order to again provide a better union between the concrete and the arch made of any material, and to likewise reduce the width of the flanges if desired. Additionally, covers (25) of polystyrene or other materials may be placed on the lower part of the ribs providing the same texture or material to the bottom of the plates. This cover may be glued or placed under pressure after concreting the plates in order to mark cavities before they are closed. Likewise, if desired it may be made integrally with the arch, in a single piece.
[0087] Instead of two ribs per plate, more ribs (2) per plate can be provided, as shown in figure 9.
[0088] In order to resolve plates resting on angled beams, the polystyrene of arches (3) can be cut to said angle, and to obtain the salient part (13) of the ribs in the support a form also consisting of polystyrene (26) may be employed, machined with the same technique, cut to the same angle and joined to the rib in factory until the final setting of the concrete.
[0089] If a great structural monolith is desired between the ribs of two different plates, aside from the compression layer and its mesh, interruptions may be made in lateral arches (27 and 28) with recoverable forms made of metal, wood or polystyrene, so that they are opposite gaps of the adjacent plate. These coffers can then be provided with a reinforcement anchored to ribs (2) so that by placing pins and filler concrete in the cavities on-site, a greater transverse stiffness of the plates is attained. In one form may be provided a straight anchored reinforcement (28) and in another hooks (27) anchored to the ribs, on which will be placed on-site tensors to compress the junction between the plates of the floor.
[0090] Figure 12 shows a double joist (29) integrated in a plate and a clamp or beam (3= parallel to the floor, which provides a support for point loads of the structure. In order to place these beams at their exact position during the construction work, arches (31) will be cut correctly on-site or in factory, using a hot wire or an electrical resistance, or with a saw.
[0091] It is not considered necessary to extend this description for an expert in the field to understand the scope of the invention and the advantages derived thereof.
1. Self-supporting polystyrene and concrete plate, of the polystyrene arch type with
a housing for the ribs or joists of reinforced or pre-stressed concrete, concreted
before installed in the construction, characterized in that the plate comprises two ribs (2), self-supporting along their entire length, with a double-T shape, and thickness and separation between ribs identical to that of the traditional
floors which they replace; and in that on the sides of each rib (2) are placed three
arches (3) of low-density polystyrene (between 10 and 20 kg/m3) or of another material, with the same thickness or height as the rib or joist, so
that due to their double T shape and because the ribs are concreted against the polystyrene
arches, the set remains retreated or attached, in order to form the prefabricated
plate (1), so that a construction worker can walk on the arches with a high safety coefficient. Due to this double T arrangement the
retreatment is effective in both flexion senses, positive and negative.
2. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1. characterized in that the shape of the flanges of the double T may be rectangular, trapezoidal, triangular, oval and/or have longitudinal protrusions (23). The top and bottom flanges may even have different sizes and shapes.
3. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1. characterized in that the thickness or height or ribs (2) and arches (3) is equal or very similar to the thickness of arches of a traditional floor for equal spans, loads, on-center distances and thickness, which is the only
way to ensure that it is fully self-supporting along its entire length, with no straining
pieces on the middle part of the plate and with a total infinite time sag lower than
L/250, as per Spanish and European Standards.
4. Prefabricated self-supporting plate of polystyrene and concrete of the polystyrene
arch type with a housing for the rib or joist of reinforced or prestressed concrete,
concreted before placed at the construction site, characterised in that in order to join the concrete of the plate rib to the concrete of the construction
compression plate and so that thte two work together, even transmitting the negative
moment frame tensions in the rib and validating this independent claim for ribs with
a top single T shape or double T shape; an upper width is calculated so that by menas
of a strong scraping or roughness (11) specifically provided for such purpose in the
concrete before setting, grade loads can be transmitted from one concrete (2) to the
other (8) without requiring a latticc or seam reinforcement in the junction of the
contact surfaces between the two concretes, with the ensuing saving in steel.
5. Prefabricated self-supporting plate of polystyrene and concrete of the polystyrene
arch type with a housing for the rib or joist of reinforced or prestressed concrete,
concreted before being placed on site, characterized in that in order to walk on the low density polystyrene arches in the construction site, without additional
safety measures, the width of the flanges is such that the overhang or salient (V)
of the arches, as measured from the edge of the lower flange (9) of the double T at
the free side edge of arch (3), must be less than the retreat height (H) as measured from the lower end of top flange (10) to the bottom surface of the
plate. In order to walk safely the arch, regardless of the vibration, must always
be retreated in the rib, thereby the double T shape. Additionally, the free distance
between the edge of the flange and the edge of the salient flange will be less than
40 cm, so that a person cannot fall through even if an arch were defective and this were
not detected.
6. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that the flanges of the double T (9 and 10) may be reduced and saw teeth (24) or longitudinal grooves added along the entire internal contact perimeter between
the arch and the concrete rib, as long as the overhang (V) is smaller than the retreat
thickness (H).
7. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that in order to reduce the cost of the plate, transport and assembly, the distance between
centers of joists or ribs (2) is identical to the on-center distances normally used
in construction of uni-directional floors, that is, 60, 70 or 80 cm; and the distance from the rib axis to the edge of the plate is half this distance.
This distance between ribs may be obtained only by virtue of the double T, as the
overhang of the arches is reduced in order to walk on them safely.
8. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that the plate may have 2, 3 or 4 ribs, depending on the width of fabrication, which will range between 80 and 250 cm, with the most common ones being 120 cm and 240 cm.
9. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that the plate may have a single rib depending on the fabrication width; ranging from 50 to 80 cm, with the most common one being 60 cm, and with any rib having a constant section which ensures its support stability with the lower flanges (9) of the double T, not
requiring supports, solid fillers or special extremities.
10. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that the bottom of the ribs may be coated with a thin layer of polystyrene, thereby preventing floatability of the arches when
the ribs are filled with concrete and making the bottom part of the floor uniform
with the same material.
11. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that bottom flanges (9) of the double T of the ribs are placed to be used as compression heads for negative moments near the supports and on the supports, even on the reinforcement joists, on the smooth beams or on
the brick walls, with the resulting saving in negative moment steel.
12. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
1, characterized in that, in certain cases, and only on the ends of the ribs, a reinforcement may be provided for cutting forces and/or grade forces, further ensuring the transmission of stresses between the concrete of rib
(2) and that of the compression layer (8).
13. Prefabricated self-supporting plate of polystyrene and concrete of the polystyrene
arch type with a housing for the rib or joist of reinforced or prestressed concrete,
concreted before being placed on site, characterized in that 1, 2 or more perpendicular ribs (22) may be provided on main joists (2) and in that by joining said ribs of the plate,
regardless of their shape, with or without a double T, they provide stiffness to the
unit as a prefabricated plate, so that it does not break during handling, transport
or lifting, without a lower continuous concrete plate on the entire plate.
14. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claims
1 and 13. characterized in that opposing lateral coffers (28) may be provided between adjacent plates, with a reinforcement anchored to the
ribs of each plate, which serve by means of a reinforcement and by mixed concrete
poured on-site, to attain a more integral transverse union of the plates. This reinforcement, which is to be placed on-site inside the
coffers, may be replaced by conventional tensors which compress the union.
15. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claims
1 and 13, characterized in that due to the arrangement of side unions (27 or 28) between plates, there is no need
of any compression layer or mesh, with the resulting reduction in costs. To this end, top flanges are greater than
usual, as they will support the entire positive moment. Negative moment steel can
be integrated in the top part of the ribs when these are manufactures, if required.
16. Prefabricated self-supporting plate of polystyrene and concrete of the polystyrene
arch type with a housing for the rib or joist of reinforced or prestressed concrete,
concreted before being placed on site, characterized in that on the ends of ribs (12) at the support area on beams or walls, regardless of the
single or double T-shape of the ribs, a concrete punch (13) projects out of the arches
in order to allow clamping of the support concrete and to integrate further the union
to beams and walls.
17. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claim
16, characterized in that these plates with a punch on their ends can rest on semi-prefabricated beams (15) of the scrap box type (16) and concrete plate (17), and said salient (13)
of the plate incorporate a lower cope (14) which absorbs the thickness of plate (17)
of semi-prefabricated beam (15), so that both plate (1) and plate (17) of the beams are level on the bottom
(18 and 19).
18. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claims
16 and 17, characterized in that the cavity between arch (3) and concrete plate (17) of the beam can be replaced by concrete mixed on-site, thereby providing a full continuity of the unidirectional floor with negative moments.
19. Prefabricated self-supporting plate of polystyrene and concrete as claimed in claims
16 and 17, characterized in that the top part of ribs (2) which are salient (13) for support may have an upper cope of a few centimeters
which aids in placing the negative moment steel of the beams along the entire width of said beams.