Construction method and geometric configuration applied to strap and beam sections made from reinforced or prestressed concrete, and concentrated tendon regions

Abstract

The present invention discloses a construction method and geometric configuration applied to strap and beam sections made from reinforced or prestressed concrete, and concentrated tendon regions, designed to optimise and reduce the cross-sectional area of concrete, thereby decreasing the weight thereof or even enabling an increase in the design tributary width thereof without the need to add weight, through the creation of voids along the length of the strap, beam or concentrated tendon regions.

Description

CONSTRUCTION METHOD AND GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS AND BEAMS, IN REINFORCED OR PRESTRESSED CONCRETE, AND REGIONS OF CONCENTRATED CABLES FIELD OF INVENTION

[0001] The present invention is applied in the field of civil construction, it is related to concrete structures in buildings, more specifically, it proposes a new configuration of the cross-section of bands (band slab / beam) and beams, in reinforced or prestressed concrete, and regions of cables concentrated in slabs supported directly on capitals / pillars that allow for savings in material, labor and the reduction of the efforts involved. BACKGROUND OF THE INVENTION

[0002] Despite representing 13% of global GDP in 2020 and continuing to grow in recent years, the construction sector still suffers from a lack of investment in innovation and technology. For this reason, in the last two decades, productivity growth in the sector has been only 1% per year, corroborating the low use of new technologies when compared to other sectors.

[0003] Another consequence caused by the lack of investment in the sector is that the methods / solutions applied are often archaic, not bringing any benefits such as saving time, materials, optimizing spaces and, consequently, lower construction costs.

[0004] As an example of archaic methods, we can mention the processes used in the construction of slabs, which most often use wooden formwork built on site by construction workers. This method is quite inefficient, requires more specialized labor and can cause errors in its execution that eventually compromise the final result of the work.

[0005] In this sense, with the aim of optimizing the process employed in In civil construction, the state of the art presents several innovative solutions, applying fast, safe and more efficient methods that depend less and less on the expertise of the worker.

[0006] An example of the state of the art are documents PI 0401402-2 and BR 20 2018 075012 2, filed by the same holder of the present patent, which present construction arrangements and systems for the assembly of standardized metal formwork using prefabricated components that provide a simple assembly solution for their elements.

[0007] In addition to optimizing assembly, these solutions ensure that the main and secondary beams have continuous spacing (which does not happen in cases of wooden formwork) between them, which eliminates problems such as weak points in the structure that can cause serious accidents when pouring concrete into the structure supported by the formwork.

[0008] With the use of metal formwork enabling standardized spacing between its stringers, it is possible to use solutions as observed in documents MU 9103189-3 and PI 0701851-7, filed by the same holder of this patent, which show us plastic forms in box formats (known as buckets), in a flat format and with grooves that fit into said stringers and complete the system for concreting the slab.

[0009] Despite the innovation in the form of slab construction, the state of the art has evolved little with regard to the construction of reinforced or prestressed concrete beams and band slabs, and regions of cables concentrated in slabs supported directly on capitals / pillars.

[0010] In the field of application of ribbed slabs we have the following typologies: supported directly on pillars (mushroom slab) and may have capitals, supported on bands (band slab / beam), supported on beams and supported directly on pillars with solid behavior. (BR1020170176991 filed by the same holder of this patent) and may have capitals.

[0011] Beams are support elements that transmit the forces from the slabs to the pillars and are structural elements in which their height is at least 2x greater than the thickness of the slab and their width is at most 3x the thickness of the slab, and are characterized by being an element that is difficult to execute, since it uses wood and, consequently, specialized labor.

[0012] The bands (slab / beam) are support elements that also transmit the forces from the slabs to the columns and are generally the same thickness as the slab to facilitate the execution of the forms, and allow the slabs to be configured as bidirectional or unidirectional.

[0013] Ribbed slabs supported directly on pillars (mushroom slabs) are designed to receive loads directly from the slabs and may have a square or circular capital, with the slab resting on it. This system is characterized by the absence of beams or bands (slab / beam), however, it is viable for spans between equidistant pillars, there is a greater consumption of material and, necessarily, the slabs are configured as bidirectional.

[0014] In ribbed slabs supported directly on columns with solid behavior, the columns are designed to receive the loads directly from the slabs and may have a square or circular capital, whose slab rests on it. This system must necessarily be prestressed, has a maximum interaxis of ribs of 65 cm, meets the maximum spacing of 120 cm of the distributed prestressing cables and has a compression rate in both directions of IMPa, is characterized by the absence of beams or bands (band slab / beam). Its great advantage, although being ribbed, has solid behavior and gains greater rigidity, has better structural behavior, dispenses with table reinforcements used in ribbed slabs, has reduced heights and uses minimum passive reinforcement in the most cases.

[0015] The calculation process for ribbed slabs supported on beams and bands (band slab / beam) is significantly simpler compared to slabs supported directly on pillars and may have capitals.

[0016] For slabs with bands or beams, these elements play the central supporting role and are designed to receive and distribute the loads from the slabs to the columns. In this context, the slabs are considered secondary elements, designed to transfer their loads directly to the beams or bands or beams. This implies that the beams or bands or beams assume the main function of directing the loads to the columns.

[0017] As for slabs supported directly on pillars, which may have capitals, whether ribbed or solid, reinforced or prestressed concrete, we find structural systems that are distinguished by the absence of beams or bands (slab / beam). This system is more complex both in the calculation process and in the distribution of loads and, for this reason, the use of advanced engineering software and in-depth technical knowledge arises. Here, the slabs are designed to receive the loads directly from the areas that cover them and, with the absence of beams or bands (slab / beam), they distribute the forces directly on the pillars, and may have capitals.

[0018] In summary, in slabs supported by beams or bands (slab / beam), these elements play a central role in the distribution of loads, requiring a greater amount of reinforcement in these regions and requiring stirrups, reinforcement that is difficult to execute. On the other hand, in slabs supported directly on the columns, the loads are distributed uniformly on the surface of the slab, with reinforcement being essentially uniform across its entire surface, prioritizing the concrete section as a whole, with a greater concentration of reinforcement in the regions of the columns, and may have capitals.

[0019] Whether they are reinforced or prestressed concrete beams or band slabs, since to increase their capacity to reach a greater span or load, more concrete is required (due to the increase in width and / or height) and more steel, prestressed or not, in this region (due to its greater weight), which significantly increases the weight of the structure and material costs, especially in the reinforcement, as there is a need to place stirrups, greatly increasing specialized labor and material.

[0020] In this sense, combined with the knowledge present in the state of the art, this patent proposes a new geometry of strips, capable of allowing the reduction of the area of ​​its concrete section, and also allowing the reduction of the span of the slab by increasing the width of the new calculation region, without increasing its weight, since the new geometry is no longer solid and does not require stirrups, forming a system composed of slabs + ribbed strips + capitals / pillars. In addition, it is still possible, with the developed shape, to increase the efficiency of prestressing, being able to achieve greater spans and loads and save prestressing steel, and depending on the height / width ratio in relation to the thickness of the slab, create beams without using wood, which is the greatest cost of this structural element.

[0021] The geometric change of the bands, previously solid, now with ribbed or similar regions, and supported on capitals / pillars, allows for the elimination of stirrups, reducing the span of the slab by increasing its width and providing savings in concrete, of up to 60% in the band slab / beam region, steel and, mainly, labor, which is currently the bottleneck of the construction industry.

[0022] Apparently, the new geometric model of strips+pillars / capitals can be confused with the ribbed slab supported directly on the pillars (mushroom slabs), however, the mushroom slab system does not have strips, only pillars, it can have capitals, it is only calculated as a bidirectional slab and the spans need to be equidistant in both directions. This patent differs from the state of the art in that it has strips (now ribbed or similar) that connect the capitals / pillars, allowing structures with larger spans to be built, without the need for equidistant spans, can be calculated as bidirectional and unidirectional slabs, and entails less consumption of material and labor.

[0023] When applying the invention to the system in which the ribbed slabs are supported directly on pillars, but with solid behavior, the change from the previously solid configuration to ribbed or similar regions results in a decrease in the volume of concrete, of up to 60% in the region of concentrated cables, and steel, and in the distributed prestressing cables, there is also a decrease in their quantity, since previously they needed to guarantee a compression stress of IMpa in a solid region (the region of concentrated cables), and now as it is ribbed or similar, there is a decrease in the concrete section, that is, its compression area is smaller to guarantee IMpa, resulting in fewer cables to guarantee this compression stress prescribed by standard.In some cases, there is a reduction of up to 50% in prestressing steel in the regions of distributed cables, and with the developed shape, the efficiency of prestressing is increased, being able to achieve greater spans and loads and save steel in the regions of concentrated cables. SUMMARY OF THE INVENTION

[0024] The present invention reveals a METHOD OF CONSTRUCTION AND GEOMETRIC CONFIGURATION ADOPTED IN STRIP AND BEAM SECTIONS, IN REINFORCED OR PRESTRESSED CONCRETE, AND REGIONS OF CONCENTRATED CABLES developed with the proposal of optimizing and enabling the reduction of the concrete section area, consequently reducing its weight or even enabling the increase of its calculation influence width without the need to increase its weight. Both possibilities result in savings of concrete and steel when considering the set of ribbed slabs supported directly on pillars (mushroom slab), supported on strips (band slab / beam), supported on beams, and supported directly on pillars with solid behavior.

[0025] The construction method uses the system of buckets or similar (already known in the state of the art for the construction of slabs) and / or plastic forms (or any other rigid polymer) developed specifically for the application proposed in the patent in the construction of bands (band slab / beam), reinforced or prestressed concrete beams and regions of concentrated cables with empty spaces.

[0026] After the placement of the buckets or similar, the section of the band slab / beam, beam or regions of concentrated cables, no longer have a solid shape, acquiring free spaces and with the reinforcements positioned in the "teeth" formed in the region, and formation of capitals in applications in bands. Some of the advantages of using the present patent in relation to the state of the art is the elimination of the stirrup reinforcement, the reduction of the concrete section and a great reduction in labor, which is the biggest bottleneck in the civil construction industry.

[0027] Another possibility is the use of gutters (similar to documents BR1020210206586 and PI090500-9 of the same holder) and plastic forms developed specifically for the use proposed in this patent in place of the buckets already used in the construction of the slab. In this case, the so-called “tooth” formed by the buckets would be lowered a few centimeters, but without eliminating the reduction in the cross-sectional area in relation to the state of the art, as it would still have empty spaces in its final configuration. In addition, it is still possible, with the developed form, to create beams without the use of wood and specialized labor, which is the highest cost of this structural element.

[0028] It should be noted that the effect of prestressing is proportional to the distance at which the prestressed tendon is fixed in relation to the highest position of the concrete section. For example, a 25cm slab, creating a 15cm recess, already incorporated in the developed form, there is a 60% increase in the effect of prestressing. In other words, by positioning the tendon in the recess created by the new form, the effect of prestressing is increased, thus enabling a reduction in the number of cables, an increase in spans and loads and a reduction in the dimension of the structures.

[0029] Furthermore, reducing the section area allows for an increase in the width of the band slab / beam section without increasing its weight, which can even be smaller, and, consequently, a reduction in the slab span, since part of the constructed area where the slab would be positioned now has the band slab / beam widened.

[0030] It is important to emphasize that the slab represents around 70% of the entire structure and a reduction in its span by widening the band (slab / beam) would provide even greater savings in concrete and steel than the savings achieved by just the new geometry of the band (slab / beam).

[0031] To demonstrate in the simplest way the benefits achieved by the proposal in this patent, the calculation for the band slab / beam dimensioning was simplified to observe that the size of the slab span directly interferes in the calculation of the moment.

[0032] The maximum bending moment is used to size the slab (dimensions, concrete volume, amount of active and passive reinforcement) and follows the (simplified) formula below, where “q” represents the total load uniformly distributed throughout the region, “l” represents the distance between the bands (band slab / beam) and “M” the maximum bending moment:

[0033] This result is extremely important because, as can be seen in the formula above, the forces involved in the construction of a slab are proportional to the square of its span. Therefore, by increasing the width of the bands (slab / beam), thus reducing the span of the slab, there is a drastic reduction in the forces involved and, consequently, the need for larger volumes of concrete and active and / or passive reinforcement in the slab to support these forces is reduced.

[0034] In the above, as a result of the increase in the width of the lane (band slab / beam), if an 8-meter slab span is reduced to 6 meters, there is a 43.75% reduction in the requesting forces, therefore, the dimensioning of the slab region takes into account this reduction in the maximum bending moment, requiring less concrete and active and / or passive reinforcement for its manufacture.

[0035] To illustrate a complete pavement, studies were prepared comparing the various unidirectional systems with equidistant spans of 8 meters between columns, considering the price of concrete materials at R$400.00 / m3, passive reinforcement at R$7.00 / kg and active reinforcement at R$17.00 / kg, (i) conventional reinforced concrete model (high beam with wooden formwork), (ii) model with solid strips embedded in the slab, (iii) model with optimized and widened strip and (iv) model with optimized and lowered strip. Compared to model (ii), model (iii) saved 18.9% in materials, and model (iv) saved 22.2% in materials.

[0036] Now, comparing model (ii) with (i), there was no significant saving in material, however, in terms of labor, there is a saving of at least 30%, since model (i) is executed using a wooden form, consequently, more specialized labor.

[0037] Comparing models (iii) and (iv) with model (ii), which is a model with solid strips embedded in the slab, a system that is already efficient compared to (i), in terms of labor, it is estimated that there will be savings of up to 30% in specialized reinforcement labor, since there are no more stirrups. The table below shows the comparisons between the systems.

[0038] All this information is best viewed in the table below:

[0039] In the application of the invention in the system in which the ribbed slabs are supported directly on pillars, but with solid behavior, and may have capitals, the change in the configuration of the concentrated cable region, previously solid, to a ribbed or similar configuration, there is a decrease in the volume of concrete and, consequently, steel (active and passive), and in the distributed prestressing cables, there is also a decrease in their quantity, since before they needed to guarantee a compression stress of IMpa in a solid region, and now, as it is ribbed or similar, there is a decrease in the concrete section, that is, its compression area is smaller to guarantee IMpa, resulting in fewer cables to guarantee this compression stress prescribed by standard.In some cases, there is a reduction of up to 50% of prestressing steel in the regions of distributed cables, and with the developed shape, with the built-in recess, the efficiency of prestressing is increased, being able to reach greater spans and loads and save steel (passive and active) in the regions of concentrated cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 shows the isometric view of the buckets and reinforcement prepared for the configuration of a ribbed slab supported directly on capitals / pillars (100).

[0041] Figure 2 shows the same model as Figure 1, now after concreting, with the lower isometric views and a section perpendicular to the slab plane (1), where it is possible to see the pillars (5) with the capitals (6) and the active reinforcement (13), longitudinal reinforcement (14) and the table reinforcement (15).

[0042] Figure 3 shows the isometric view of the buckets and reinforcement prepared for the configuration of a ribbed slab supported on strips (200).

[0043] Figure 4 shows the same model as Figure 3, now after concreting, with the lower isometric views and a section perpendicular to the slab plane (1), where it is possible to see the pillars (5) with the strips (2) and the active reinforcement (13), longitudinal reinforcement (14) associated with the stirrups (16).

[0044] Figure 5 shows the isometric view of the buckets, forms made with wood and reinforcement prepared for the configuration of a ribbed slab supported on beams (300).

[0045] Figure 6 shows the same model as Figure 5, now after concreting, with the lower isometric views and a section perpendicular to the slab plane (1), where it is possible to see the pillars (5) with the beams (3) and the active (13) and longitudinal (14) reinforcement associated with the stirrups (16).

[0046] Figure 7 shows the isometric view of the buckets, flat shapes and reinforcement prepared for the configuration of a ribbed slab supported directly on capitals / pillars with solid behavior (400).

[0047] Figure 8 shows the same model as Figure 7, now after concreting, with the lower isometric views and a section perpendicular to the slab plane (1), where it is possible to see the pillars (5) with the regions of concentrated cables (4) and the active reinforcement (13) and minimum reinforcement (14).

[0048] Figure 9 shows the isometric views of the buckets, half buckets, channels, specific shapes and reinforcements prepared for the new configurations of ribbed slabs supported directly on widened and optimized strips (501), on optimized strips (502) and on optimized strips with recesses (503), on optimized beams (505).

[0049] Figure 10 shows the same models as Figure 9, now after concreting, with the cuts perpendicular to the slab planes (1), where it is possible to see the pillars (5) with the optimized strips (2), the active reinforcements (13), longitudinal reinforcements (14), table reinforcements (15), teeth (12), voids (11) and recesses (18).

[0050] Figure 11 shows the isometric views of the buckets, half buckets, channels, specific shapes and reinforcements prepared for the new configurations of ribbed slabs supported directly on columns / capitals, with optimized concentrated cable regions (504) and on optimized concentrated cable regions with recesses (506).

[0051] Figure 12 shows the same models as Figure 11, now after concreting, with the cuts perpendicular to the slab planes (1), where it is possible to see the pillars (5) and regions of concentrated cables (4), active reinforcement (13), minimum reinforcement (14), teeth (12), voids (11) and recesses (18).

[0052] Figure 13 shows examples of the form models: bucket (21), half bucket (22), gutters (23), specific shape (24), flat shape (25) and rib cover (26).

[0053] Figure 14 shows the assembly of the half-cube (22) and channel (23) type forms to form the recesses (18) and voids (11).

[0054] Figure 15 shows the assembly of the half-cube-type forms (22) and a second channel configuration (23) to form the recesses (18) and voids (11).

[0055] Figure 16 shows the assembly of a pair of specific shapes (24) to form the recesses (18) and voids (11).

[0056] Figure 17 shows the specific shape (24) that has recesses (18.1) and projections (11.1). DETAILED DESCRIPTION OF THE INVENTION

[0057] The present invention proposes a GEOMETRIC CONFIGURATION ADOPTED IN STRIPS AND BEAMS, IN REINFORCED OR PRESTRESSED CONCRETE, AND REGIONS OF CONCENTRATED CABLES, having several voids (11) formed from molds arranged along the length of the strip (2), beam (3) or regions of concentrated cables (4). Between these molds (20) teeth (12) are formed where the active (13) and / or passive (14) reinforcements are positioned, and may have recesses (18) that optimize the effect of prestressing.

[0058] In these regions, the passive and / or active reinforcements (14 and 13) are positioned in the so-called “teeth” (12). After concreting, the passive and / or active reinforcements (14 and 13) are positioned in the teeth (12) shown in your section.

[0059] The molds used are preferably prefabricated forms in the shape of cubes (21) or similar, which may have different sizes depending on each project carried out. In the examples disclosed in this patent, the molds such as cubes (21) or similar are configured for various modularizations, such as 80 by 80 or 61 by 61, or even half cubes (22) or similar, such as 80 by 40 and 61 by 30.5 (measurements in cm).

[0060] Another possibility is the use in conjunction with gutters (23 - similar to those present in documents BR1020210206586 and PI0905001-9), from the same holder, and plastic forms developed specifically for the application proposed in the patent (24), for the formation of recesses (18) of a level lower than the level of the teeth (11) between the cups (21) and / or half cups (22) of the slab (1), beam (3), strip (2) or regions of concentrated cables (4). Said recesses (18) formed by the prefabricated forms of specific geometry (24) and / or gutters (23) are preferably between 8-40 cm in depth, and may have other dimensions.

[0061] It is important to clarify that in the present patent the use of gutters (23) is always associated with the trays (21) and / or half trays (22) or even with specific shapes (24) so ​​that empty spaces (11) are generated in the areas of strips (2), beams (3) or regions of concentrated cables (4).

[0062] There is also the possibility of forming using polystyrene plates or even wooden or metal elements, however, these options reduce the speed of execution of the structure and there is no guarantee of conformity of the size and spacing of each void, and they are non-reusable and non-sustainable materials, and require more labor.

[0063] The specific shapes (24) for the application presented in this patent present recesses (18.1) responsible for the conformation of the recesses (18) of the strips (2), beams (3) or concentrated cable regions (4) and also present protrusions (11.1) which in turn are responsible for forming the voids (11) in the same areas mentioned above.

[0064] The present invention also proposes a METHOD FOR CONSTRUCTING STRIPS AND BEAMS, IN REINFORCED OR PRESTRESSED CONCRETE, AND REGIONS OF CONCENTRATED CABLES comprising the placement of modularized forms of the type of cubes (21) and / or half cubes (22) and / or the association of the cubes (21) and / or half cubes (22) with the gutters (23) and / or specific forms (24) or even the use only of the specific form (24) in areas of strips (2), beams (3) or regions of concentrated cables (4) which subsequently receive the active (13) and / or passive (14) reinforcements between the teeth (12) formed by the forms (20), being concreted and, after the concrete has cured, the forms (20) are removed, thus forming the said areas comprising the voids (11).

Claims

CLAIMS 1) GEOMETRIC CONFIGURATION ADOPTED IN SECTIONS OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES made of reinforced or prestressed concrete and formed by plastic or polystyrene or wooden or metallic molds, characterized by the section having several voids (11) formed from molds arranged along the length of the strip (2), beam (3) or regions of concentrated cables (4), where, separating the empty spaces (11), there are teeth (12) which in turn receive the active (13) and / or passive (14) reinforcements. 2) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claim 1, characterized by the presence of recesses (18) at a level lower than the level of the teeth (12). 3) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claim 1, characterized by the fact that the prefabricated molds comprise cups (21) and / or half cups (22). 4) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claim 2, characterized by the fact that the prefabricated molds comprise the association between one or more molds of the types: buckets (21) and / or half bucket (22) with gutters (23) and / or specific shape (24) or even the use of only the specific shape (24). 5) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claims 3 or 4, characterized by the fact that the prefabricated molds be associated with rib covers (26). 6) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claims 3, 4 or 5, characterized by the fact that the prefabricated molds have standardized dimensions 80 by 80 or 61 by 61 or 80 by 40 or 61 by 30.5 in centimeters. 7) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claims 4 or 5, characterized by the fact that the specific shapes (24) present recesses (18.1) for forming the recesses (18) and protrusions (11.1) which in turn are responsible for forming the voids (11) of the strips (2), beams (3) or regions of concentrated cable (4). 8) GEOMETRIC CONFIGURATION ADOPTED IN SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES according to claim 2, characterized by the recesses (18) at a level lower than the level of the teeth (12) having a depth between 8-40 cm. 9) METHOD OF CONSTRUCTION OF THE SECTION OF STRIPS, BEAMS AND REGIONS OF CONCENTRATED CABLES with geometry characterized by claim 1 or 2, characterized by comprising the placement of modularized forms of the type of cubes (21) and / or half cubes (22) and / or the association of the cubes (21) and / or half cubes (22) with the channels (23) and / or specific forms (24) or even the use only of the specific form (24) in areas of strips (2), beams (3) or regions of concentrated cables (4) that subsequently receive the active (13) and / or passive (14) reinforcements between the teeth (12) and / or recesses (18) formed by said forms, being concreted and, after the concrete has cured, the forms are removed.

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