EP1067249A2

EP1067249A2 - A laid monolithic ceiling out of cement reinforced concrete and the relative process for realizing the same

Info

Publication number: EP1067249A2
Application number: EP00202226A
Authority: EP
Inventors: Corrado Cavani
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-07
Filing date: 2000-06-26
Publication date: 2001-01-10
Also published as: ITCR990007A1; EP1067249A3; ITCR990007A0

Abstract

A laid monolithic ceiling out of cement reinforced concrete comprising. extrados beams (2) that cooperate like a monolyth with a cast slab (1) in which they are partially inserted. The realization process of said laid comprises the following phases:

the building of at least two carrying pillars;
the realization of an intrados formwork supported by props;
the formation of the iron reinforcing of the slab and of the extrados beams;
the filling of the formworks with cement for the cast of the slab and of the portion of the extrados beams inserted into said slab;
the realization of the formwork projecting from the extrados of the slab for the finishing cast of the extrados beams.

Description

The present invention concerns a laid monolithic ceiling out of cement reinforced concrete and the relative process for realizing the same.
In particular, the present invention concerns a ceiling particularly suitable for the realization of structures for plane or not plane covers, out of conventional reinforced concrete and postcompressed reinforced concrete, for building works in civil, military and industrial fields.
At present, the most widespread technique for realizing the cover of great spaces for industrial sheds, civil buildings, public works, military works, mainly consists in the prefabricated cover that may be realized in different ways: like covers with precompressed reinforced concrete beams, with an Y-shaped section, or with big precompressed reinforced concrete tiles, or with the less used solution of gable beams out of precompressed reinforced concrete. Further solutions may consist of a metal structure, laminate wood, tensostructures or however other techniques or materials that allow the increase of the free cover spaces and consequently greater free exploited and at disposal surfaces. A great space usually means the space between the resting points of the ceiling that varies betwee 15 and 40 meters. Above mentioned realizatio techniques have one common feature, i.e. the fact that most of the structural elements are prefabricated in places different from the building yard, like e.g. prefabricated elements out of precompressed reinforced concrete and metallic shapes etc. Such prefabricated elements determine an increase in the realization costs, due to the particular transportation manner requested for the transfer to the building yard with consequent problems for the use of the roads. The moving of said elements in the building yard requires the use of extraordinary lifting means, such that make the safety of the building yards precarious or however difficult. But there are also other lack that characterize said technologies. The cover of great spaces with the precompressed reinforced concrete technique, completed with light element with the criterium of simple supports, does not form a monolithis realization that may guarantee in time the absolutly static nature of said structure. The dynamic actions caused by the wind, by the natural and artificial thermal expansion due to fire, natural catastrophies, great snowfalls or seismis movements, determine the arising of safety problems for the structure and for the workers that are working inside the building, due to possible falls of secondary structural elements. Furthermore, the insulation is not easy to be realized as it is applied without continuity, leaving some areas uncovered and thus creating thermal gaps and thus great heat dispersion or thermic ranges.
It is the aim of the present invention to eliminate above mentioned inconveniences.
A particular care has been deserved to the quality of the product and to a low cost production. Infact great amounts of building work productions are requeste in Italy and in Europe, and furthermore the client has become still more demanding in the request of the finished product.
The aims set forth are reached by means of the object of the present invention which consists of a laid monolithic ceiling out of cement reinforced concrete, characterized in that it comprises extrados beams which cooperate as a monolyth with a slab laid during realization.
Extrados beams are beams with any shape and section, placed at suitable distances according to the structural calculations, and realized out of materials fit for resisting to load actions; they are made monolithis with the slab by means of a cement cast and at least one portion of the square section is projecting with respect to the extrados of said slab.
For realization needs and economy the extrados beams may be out of cement reinforced concrete with a slow or postcompressed reinforcing; with reticular iron beams or with other materials that may solidarize with the cover slab by means of a cement cast.
The realization process for obtaining the laid monolithic ceiling out of cement reinforced concrete, comprising a slab and extrados beams, is characterized in that it comprises the following phases:

In the case of lightened ceilings, the realization phase of the slab consists in a first cement cast inglobing the lower reinforcing iron, the laying of the perforated blocks out of polystyrene and of the upper reinforcing iron, the completing cement cast of the slab up to the extrados. The full ceilings as well as the lightened ones are furthe protected with a waterproofing coating of known kind.
Many advantages derive from the product and process according to the present invention.
The finished structure is a monolithic one and is completely realized in loco; thus, all problems linked to a special transport and to particular lifting systems requested for prefabricated elements are eliminated, and a greater safety in the building yards is obtained. This has been made possible, once the formworks have been laid, by the new working process, with the final result that extrados beams and slab are completely integrated into one single structural section, i.e. a monolithic section, completely realized in loco. This result improves the times and the realization safety of the works, thus allowing to obtain a finished product with undiscussed better features that resists to possible natural catastrophies and of other kind, seismic movements, great showfalls, fire. The fire resistance of the structures according to the present invention is highly improved: according to the needs, the structural stability may last two hours or even longer, against the 20-30 minutes of the precompressed reinforced concrete or steel structures, which undergo greater structural damage with the risk of an immediate collapse of said structures.
The safety degree of the works realized by means of the new process greatly respects all building laws of the national and European market.
The new building process allows a reduced time for preparing the formwork structures in the building yard, thus improving the productivity or the work, and therefore reduced costs. It favours a more careful analysis of the project and of the realization drawings of the structures, creating maximum safety conditions for the workers in the building yard.
Furthermore, the new working process may be used for building any kind of conventional plane structures out of reinforced concrete, concerning the building production of industrial sheds, civil buildings, public works, military works, however with a special reference to the improvement of the building process by simplifying the mounting of the supporting bracing of the work in loco and the course of the building process.
Other features and advantages of the object of the present invention will appear more clearly from the detailed specification following hereinbelow, with reference to the enclosed drawings in which a prefered embodiment is shown.
Figure 1 shows a perspective view of a ceiling according to the present invention.
Figure 2 shows a square section parallel to the extrados beams of the ceiling according to figure 1.
Figure 3 shows a square section perpendicular to the extrados beams of an enlarged detail of the ceiling with a full slab.
Figure 4 shows the ceiling of figure 3 with a tightened slab.
Figure 5 shows an enlarged detail of the perimetric jutting out eaves for the collection of the rain.
Figure 6 shows the same detail of figure 5, with non jutting out eaves.
Figure 7 shows a square section perpendicular to the extrados beams, of an enlarged detail of the ceiling with a lightened slab, with formworks and props for supporting the cast of the slab 1 and of the extrados beams 2.
In the case of small spaces - between 3 and 5 meters - said slab 1 has an advantageously full section, comprising reinforcing irons or nets 3 englobed in a monolithic cement cast 4.
In this case, the insulation material of the ceiling is placed above the full section slab.
In the case of great, spaces - between 15 and 40 meters - due to reasons of structural weight and insulation, polystyrene blocks 5 are advantageously provided in said slab 1, between the upper and lower iron reiforcing.
The extrados beams 2 comprise a portion of their section inserted inside said slab 1 and a portion projecting above the extrados of said slab.
Advantageously, said beams are realized with cement concrete and reinforcing irons 6. The reinforcing irons may be of the conventional kind (slow) or postcompressed.
In a variant according to the present invention, said beams are realized out of iron, with a full or reticular section, possibly protected with anticorrosive surface treatments.
The extrados beams 2 are resting onto at least two rows of pillars 7, which determine the span of the ceiling. Said pillars 7 are advantageously realized out of reinforced concrete.
Along the circumference of the ceiling, or at least along one side of the same, eaves 8 are advantageously provided.
Such eaves may be jutting up or not with respect to the row of pillars 7 and is limited by a containing wall 9. Furthermore, said eaves comprise holes 10 conected to discharge down pipes 11. The wall 9 is provided with overflow holes 12 for discharging the water not discharged by the downpipes 11 due to possible obstructions caused by leaves or dirt accumulated inside the eaves, and that will prevent with absolute certainty the water from penetrating the building.
The process for the realization of a ceiling according to the present invention, specially with a full slab, is the following:
The first phase provides the building of rows of carrying pillars 7 out of reinforced concrete onto plinths 15 or beams or foundation slabs.
Then the formwork is realized for supporting the slab during the cast and cement maturation phase.
Such formwork may be advantageously realized with reusable formworks 13 and props 14, easily available on the market.
Now the conventional reinforcing with a metal net and reinforcing iron rods 6 of said slab 1 and of said extrados beams 2 is placed.
Then the cement cast of said slab 1 and of the portion of the extrados beams 2 inserted inside said slab is performed. The extrados of said slab may be advantageously shaped with an inclined surface that favours the running of the water towards eaves 8.
A few days later the frameworks are realized onto said slab, projecting for the completing of the extrados beams and of the eaves wall in correspondence with the respective reinforcing projecting from said slab, already provided before the cast of the slab.
The finishing cast of the portions of the extrados beams external to the slab and to the eaves wall is performed.
Finally, the thermic insulating and the waterproof sheeth of known kind may be laid.
In the case of lightened slab, the realization process of the same initially provides the realization of a first cement cast englobing the lower reinforcing iron, then the laying of perforated blocks (shaped blocks) out of polystyrene (or other equivalent material) and of the upper reinforcing iron, and finally the completing cement cast of the slab up to the extrados.
In both kinds of ceiling, openings may be made in the slab for realizing windows and skylights, as requested by higienic laws.
According to the present invention, once the project of a monolithic industrial shed has been studied, the project of the carrying structure of formwork and props for the slab and the extrados beams must be worked out. This project is necessary for improving the future safety of the building yard and for reducing the time for assembling the panels for formworks and props and therefore also improving productivity and reducing the assembling cost, which is a contributing factor for the final cost of the work. Once the building yard has been prepared, at first the perimetric pillars 7 are realized with the relative foundation plinths 15, or beams or slabs, which will carry the whole monolithic structure. The pillars will have an indicative pitch comprised between a minimum of 3 meters and a maximum of 15 meters, and for a span of the ceiling in the other direction, between a minimum of 5 meters to a maximum of 40 meters. The next phase - once the pillars have been freed from the formwork - is the realization of the carrying formwork structure 13 and of the props 14 for supporting the full or lightened slab which, due to building needs, is housed inside the polystyrene blocks 5.
For the full slab or ceiling, the renforcing 6 is laid and then the cast in one single solution.
For the lightened slab, the lower reinforcing is laid and a first cast of 5 cm is made. Then the polystyrene blocks are laid, with a height variable according to the work to be performed. After this phase, the upper net may be placed on the polystyrene and the reinforced concrete cast may be made up to 2.5 cm above the iron, for assuring the thickness for hiding the iron.
During the operation of reinforcing the lightened slab (with iron rods and lower and upper net), the reinforcing for the future realization of the extrados beams may be prepared, which will remain linked to the reinforcing of the full or lightened slab.
Once the worker has completed the formwork of the extrados beams, the third cement reinforced concrete cast is made for completing the portions projecting beyond the extrados of the slab of the extrados beams, thus reaching the aim of the present invention, to realize a monolithic reinforced concrete structure. After a technic time period, the last phase to be performed in the building yard is the process of removing the formworks, i.e. removing all formwork panels and all props of the lightened slab of full celing as well as of the extrados beams.

Claims

A laid monolithic ceiling out of cement reinforced concrete, characterized in that it comprises extrados beams (2) that cooperate like a monolyth with a cast slab (1).
A ceiling according to claim 1, characterized in that the extrados beams (2) comprise a portion of their section inserted inside said slab (1) and a portion projecting above the extrados of said slab.
A ceiling according to claim 1, characterized in that the extrados beams. (2) are out of cement reinforced concrete with conventional low or post compressed
A ceiling according to claim 1, characterized in that the extrados beams (2) are out of iron.
A ceiling according to claim 1, characterized in that said slab (1) has a full section comprising reinforcing irons (3) or nets englobed in a monolithic cement cast (4).
A ceiling according to claim 1, characterized in that said slab (1) has a light section comprising blocks (5) of polystyrene placed between the upper and lower irdon reinforcing.
A ceiling according to claim 1, characterized in that at least along one side of the ceiling an eaves (8) is realized that juts out with respect to row of pillars (7), and which is limited by a containing wall (9) comprising holes (10) connected to discharge downpipes (11) and overflow holes (12).
A realization process for a laid monolithic ceiling out of cement reinforced concrete comprising a slab and extrados beams, characterized in that it comprises the following phases:

the building of at least two carrying pillars;

the realization of an intrados formwork supported by props;

the formation of the iron reinforcing of the slab and of the extrados beams;

the filling of the formworks with cement for the cast of the slab and of the portion of the extrados beams inserted into said slab;

the realization of the formwork projecting from the extrados of the slab for the finishing cast of the extrados beams.
A realization process according to claim 8, characterized in that it provides initially the realization of a first cement cast englobing the lower reinforcing iron, then the laying of lihtening perforated block and of the upper reinforcing iron, and finally the completing cement cast of the slab up to the extrados.
A building characterized in that it comprises a ceiling realized according to the preceding claims.