Technical Field

The present invention relates essentially to the construction industry, specifically to the production of the reinforced concrete beam of increased load-carrying capacity and enhanced resistance against the impact of various external factors.

Background Art

For the production of presently known reinforced concrete beams, the reinforcement and concrete are used. For the production of presently known concrete beams, the wood formworks or forms of various materials are used (SU 1765327, 12.11.1990).

When the beam is of a complex shape, the main disadvantage of the conventional method of production of reinforced concrete beam is that the mounting of formworks is time-consuming, and standard moulds for producing beams mostly are straight-lined; consequently, the production results in high labour costs. In order to obtain the beam of lean and streamlined shape, the wood formworks are used; therefore, obtaining a regular form without a geometrical deviation practically is impossible (very high material and labour costs). When an arched beam is fabricated by means of wood formworks, the external surface of the beam is more or less angular; therefore, a regular geometrical form is not obtained. The load-carrying capacity of presently known reinforced concrete beams depends on two components: concrete and reinforcement. For this reason, big beams have a very large cross-section and great self-weight. Where the beam has a very large cross- section and length, the structure is heavy and visually very large. Such beam lacks a streamlined shape and transfers heavy loads to the substructure. Presently known conventional reinforced concrete beams mostly are of straight lines and, depending on the loading on and length of the beam, have a large cross-section. When conventional reinforced concrete beams are used for the fabrication of protruding structures of the building (balconies, terraces, protruding or similar elements of the building), the main disadvantage of such beams, depending on the length of the protruding segment, is a large cross-section and heavy self- weight of the beam structure. 09/000013

2 Summary of Invention

The objective of the present invention is to provide a technique for the production of a beam of a higher load-carrying capacity, reduced cross-section, protected against any impact of external factors, and of any shape. Low labour and material costs of production shorter process of production and assembling. Reduction of the cross-section and self- weight of the beam. At low labour costs, production of beams having light, streamlined, graceful and regular geometrical and three-dimensional shapes. Increase the load carrying capacity of the beam without increasing its cross-section and self-weight. Application of the structure of beam for various purposes such as load-bearing beams, headers, supporting beams, balconies, protruding elements of the building, flight footings, flights of stair and other structures. Exploitation of the beam in aggressive environments and severe climatic conditions. Protection against the impact of environmental effects, heat, frost, fire, chemical factors, earthquake, external physical factors, and shock. Providing maximum durability of the beam. The main characteristic of the present invention is that the frame of beam, which contains the frame, reinforcement, and concrete, is built out of stay-in-place metal formworks and internal stiffening metal strips. The external metal formworks may be the stay-in-place metal formworks or the external metal formworks may be the removable metal formworks. For the production of the beam, formworks and stiffening metal strips are used.

For the production of the frame, removable and/or stay-in-place external metal formworks and internal stiffening strips are assembled, the reinforcement is embedded, concrete mix is poured, and, after concrete has cured to a required strength, the removable metal formworks are stripped, and the stay-in-place external metal formworks and internal stiffening strips are left in place.

Brief Description of Drawings

A better understanding of the invention will result from the following description of the cantilevered tread with reference to the following drawings:

Fig. 1 (a-b) - The beam, the frame of which is built out of stay-in-place metal formworks: a) - Cross-section; b) - Longitudinal section A Fig. 1 (c-d) - The beam, the frame of which is built out of removable metal formworks and internal stiffening metal strip: c) - Cross-section; d) - Longitudinal section B

Fig. 1 (e-f) - The beam, the frame of which is built out of stay-in-place metal formworks and internal stiffening metal strip: e) - Cross-section; f) - Longitudinal section C

Fig. 2 (a-b) - The beam, the frame of which is built out of stay-in-place metal formworks: a)- Cross-section; b) - Longitudinal section A; Fig. 2 (c-d) - The beam, the frame of which is built out of removable metal formworks and internal stiffening metal strips: c) - Cross-section; d) - Longitudinal section B;

Fig. 2 (e-f) - The beam, the frame of which is built out of stay-in-place metal formworks and internal stiffening metal strips: e) - Cross -section; f) - Longitudinal section C

Fig. 3 (a-b) - The beam, the frame of which is built out of stay-in-place metal formworks: a) - Cross -section; b) - Longitudinal section A

Fig. 3 (c-d) - The beam, the frame of which is built out of removable metal formworks and internal stiffening metal strips: c) - Cross -section; d) - Longitudinal section B

Fig. 3 (e-f) - The beam, the frame of which is built out of stay-in-place metal formworks and internal stiffening metal strips: e) - Cross-section; f) - Longitudinal section C Fig. 4 (a-c) shows beams produced in three shapes, of many possible: a) - Ellipse-shaped beam in a plane view; b) - Arch-shaped beam in a plane view; c) - Curved beam in a three-dimensional view

Description of the Preferred Embodiments Figure 1 - Figure 3 (a-b) show beams, the frame of which is built out of stay-in- place metal formworks. For this structure, only stay-in-place metal formworks (1) are fabricated and assembled. For the production of such beams, once the formworks (1) have been assembled, the reinforcement (3) or metal bars (3) of required geometrical characteristics and appropriate class are mounted, depending on the purpose, length and cross-section of the structure [Figure 1 - Figure 3 (a), (c), (e)], loading and other factors. Once the formworks (1) and reinforcement (3) have been assembled, concrete (2) of appropriate density, structure, and class is poured on the structure; concrete of exposure class may be used, if necessary. The load-carrying capacity of such beams depends on the following three components, which determine the load-carrying capacity: stay-in-place metal formworks (1), reinforcement (3) and concrete (2). Beams of this type have an advantage that a sufficiently high load-carrying capacity is achieved, depending on the thickness of the stay-in-place metal formworks (1), without the need to increase the cross- section of beams and self- weight of the structure. At low material and labour costs, it is possible to produce beams of any light shape [Figure 4 (a-c)], or of a light and streamlined 3D shape [Figure 4c]. This type of structure has a significantly higher resistance against physical impact (shock, vibration, earthquake etc.) as compared to the conventional reinforced concrete structure. Beams of this type, for production of which stay-in-place metal formworks of appropriate metal thickness, structure and class have been used and which was covered additionally with fire-resistant materials and plastered, have very high fire resistance because the beam's reinforcement and concrete is protected from the exposure to flames by the metal sheet, in this case, by stay-in-place metal formworks, fire- resistant flameproof material, plaster and appropriate paint. Figure 1 - Figure 3 (c-d) shows the beams, the frame of which consists of removable metal formworks and internal stiffening metal strips. For this structure, stay-in- place metal formworks and internal stiffening metal strips are fabricated and assembled. The technique for the production and assembling of this type of beams, compared to that of beams shown in Figure 1 - Figure 3 (a-b), is more complicated. When producing this beam, once the formworks (1) have been assembled, internal stiffening metal strips (I ¹ ) are placed, and the reinforcement (3) or metal bars (3) of appropriate properties and geometrical characteristics are embedded, depending on the purpose, length and cross- section of [Figure 1 - Figure. 3 (a), (c), (e)] and loading and other impacts on the beams. Once the formworks (I) ₅ stiffening strips (I ¹ ) and reinforcement (3) have been assembled, the concrete (2) of appropriate density, structure and class is poured on the structure; concrete of exposure class may be used, if necessary. For the production of the beams shown in Figure 1 - Figure 3 (c-d), the metal formworks (1) are used only for producing the shape of beams; these formworks are thin and have low class and geometrical characteristics because after complete curing of concrete (2), metal formworks (1) are remover from the beams. The curing time of concrete mix (2) of the beam depends on density, structure and class of concrete (2).

The load-carrying capacity of beams shown in Figure 1 - Figure 3 (c-d), as in the case of beams shown in Figure 1 - Figure 3 (a-b), depends on the following three components of load-carrying capacity: internal stiffening metal strips (I ¹ ), reinforcement (3) and concrete (2). The structure of these beams, compared to the beams shown in Figure 1 - Figure 3 (a-b), is more complex because of the production of internal stiffening metal strips (I ¹ ), assembling technique of the beam and removal of the formworks (1) from the beam after concrete (2) have been cured. It is possible to produce beams, shown in Figure 4 (a-b), similarly as beams shown in Figure 1 - Figure 3 (a-b) or Figure 1 - Figure 3 (e-f), of any shape (large dimensions, light and streamlined three-dimensional shape). The metal formworks (1) are removed from the beam. If the metal sheet, in this case, the formworks (1) are exposed to atmospheric factors (rain, sun, snow etc.), the formworks (1) are removed but the internal stiffening metal strips (I ¹ ) are left at place for ensuring the load- carrying capacity; otherwise, it would be necessary to fabricate the formworks of precious metal or protect the formworks against corrosion by using expensive materials. If, however, a particularly strong beam is required, the formworks (1) are left but it is necessary to use, for example, stainless steel formworks (1) of appropriate class and geometrical structure. If the stainless steel formwork (1) is not removed, the structure becomes of the type of beams shown in Figure 1 - Figure 3 (e-f).

Figure 1 - Figure 3 (e-f) shows the beams, the frame of which consists of stay-in- place metal formworks and internal stiffening metal strips. For this structure, stay-in-place metal formworks and internal stiffening metal strips are produced and assembled. The technique for the production and assembling of this type of beams, compared to that of the beams shown in Figure 1 - Figure 3 (c-d), is more simple because the metal formworks (1) are not stripped; however, compared to that of beams shown in Figure 1 - Figure 3 (a-b), is more complicated because the internal stiffening metal strips (I ¹ ) should be embedded as in the case of the production of beams shown in Figure 1 - Figure 3 (c-d). But unlike the beams shown in Figure 1 - Figure 3 (a-b) and (c-d), the beams shown in Figure 1 - Figure 3 (e-f) have a considerably higher load-carrying capacity. For the production of the beams shown in Figure 1 - Figure 3 (e-f), once the formworks (1) have been assembled, the internal stiffening metal strips (I ¹ ) are embedded. Considering the purpose, length and cross-section of and loading and other impacts on the beam [Figure 1 - Figure 3 (a), (c), (e)], the reinforcement (3) or metal bars (3) of appropriate class and geometrical characteristics are embedded. Once the metal formworks (1), stiffening metal strips (I ¹ ) and beams reinforcement (3) 5 or metal bars (3) are assembled, concrete (2) of appropriate density, structure and class is poured on the structure; concrete of exposure class may be used, if necessary. The formworks (1) for the production of the beams shown in Figure 1 - Figure 3 (e-f), unlike of those shown Figure 1 - Figure 3 (c-d), are left in place and are used not only for producing a shape of the beam shown in Figure 4 (a-c) but also for increasing the load-carrying capacity and protecting against various external impacts. Considering the purpose and exposure of the beam, the metal formworks (1) are fabricated of a metal sheet of appropriate thickness, class and geometrical characteristics. The load-carrying capacity of the beams shown in Figure 1 - Figure 3 (e-f) depends on the following four components of load-carrying capacity: stay-in-place formworks (1), internal stiffening metal strips (I ¹ ), reinforcement (3) and concrete (2). The structure of this type of beams, compared to that of the beams shown in Figure 1 - Figure 3 (a-b), is more complex because of the fabrication and embedding of internal stiffening metal strips (I ¹ ); however, depending on the beam's cross-section, the structure of the beams shown in Figure 1 - Figure 3 (a), (c), (e), compared to that of the beams shown in Figure 1 - Figure 3 (c-d), is more simple because metal formworks (1) are not stripped. It is possible to produce beams shown in Figure 4 (a- c), similarly as the beams shown Figure 1 - Figure 3 (a-b) or (c-d), of any shape (large dimensions, light and streamlined three-dimensional shape). If there is a direct impact of atmospheric factors (rain, sun, snow etc.) on the beam of this type, the metal sheet, in this case, the formworks (1), are affected by corrosion. Considering the future exposure to environmental effects and requirements to the structure (small cross-section [Figure 2 (e)], reduced self-weight of the structure), for the production of the beams shown in Figure 1 - Figure 3 (e-f), the formworks (1) are fabricated of metal sheets, which are resistant to atmospheric exposure and are of appropriate class and geometrical characteristics, for example, of stainless steel. Comparing by the technique of the production, the beam shown in Figure 1 - Figure 3 (e-f), compared to the beam shown in Figure 1 - Figure 3 (c-d), involves lower costs if there is no direct atmospheric exposure and no need using the stainless steel formwork (1), and is more often used for its proper purpose because the metal formworks (1) are not removed. The shape of this type of beams shown in Figure 4(a-c) is light and streamlined or three-dimensional [Figure 4 (c)], if necessary, as easily as LT2009/000013

7 in the case of beams shown Figure 1 - Figure 3 (a-b) or (c-d). If appropriate materials are used for the production, beams of this type are as resistant to atmospheric, chemical and fire exposure as the beams shown in Figure 1 - Figure 3 (a-b) or (c-d). The structure shown in Figure 1 - Figure 3 (e-f) is particularly resistant to physical impact (shock, vibration, earthquake etc.).

The metal formworks for beams may be produced from the metal sheet either in the shop floor or at the site of assembling. As the metal sheet may be rolled easily, metal elements of formworks may be produced of regular and streamlined or three-dimensional shape, at low labour costs. If the beam should be of a complex or three-dimensional shape, the metal formworks may be produced either in the shop floor or at the site of assembling but if the beam should be of large dimensions, it is produced at the site. The technique for the assembling of metal formworks is very simple (Lego principle). Each element of the formwork bears a number from 1 to n; numbers carries out the assembling of elements consecutively. Internal stiffening metal strips and metal formworks are pressed against each other; depending on the shape of the beam, elements are connected by spot, continuous or other weld seams. The principle of assembling of the beam is not declared; the assembling may be performed from 1-n or n-1, considering which option is more convenient. Once the metal formworks have been assembled, depending on the structure of the cross-section, internal stiffening metal strips, reinforcement or metal bars are embedded; finally, concrete of appropriate density, structure and class is poured on the structure; concrete of exposure class may be used, if necessary. If the beam is of simple shape (straight, arched in a plane) but of large dimensions, then the metal formworks and, if necessary, internal stiffening metal strips and reinforcement is fabricated in the shop- floor but concrete mix is poured at the site in order to avoid high labour costs when transporting the beam. The beams of small dimensions may be fully produced in the shop- floor. In case of stay-in-place metal formworks, if you need, beam finish work may be done at option. By other technique, the concrete is covered by metal cohesive materials, filler or plaster and painted by conventional paint (for wall of ceiling), or is daubed by a metal daub and painted by paint for metal. The beam may be glued over with facing materials (gypsum cardboard, decorative cladding panels etc.) depending on external impacts to the beam. Once the metal formworks have been stripped, the beam is covered by filler or plaster and painted by an appropriate paint depending on exploitation conditions. If the structure is subject to high fire safety requirements, special fire-resistant materials glue over the beam additionally; afterwards, the finish may be made, if necessary.

The novel structure of beam has the particular advantage over the conventional structure of reinforced concrete beam in that a significantly higher load-carrying capacity is achieved without the need to increase the cross-section and self-weight of the structure depending on the thickness of the stay-in-place formworks and internal stiffening metal strips. Any light shape or light streamlined three-dimensional shape, if necessary, may be obtained at low material and labour costs. The novel structure of beam is more resistant to chemical and fire exposure, and more resistant to physical impact (shock, vibration, earthquake etc.).