FI107556B - Prestressed cooperating beam - Google Patents

Description

107556

Tensioned composite beam

The present invention relates to a tensioned composite beam intended for use in combination with prefabricated panels or composite panels 5 to form a composite structure, particularly for buildings. in ceilings, lower or intermediate floors, and which joist beam includes a prefabricated profile section with a pouring opening and a prefabricated pre-cast section formed within the section section, as well as tendon and concrete steels within the prefabricated assembly; concrete casting connecting the composite structure.

Composite beams are used in modern concrete construction 15 together with ready-made slabs. In the construction phase, the finished slabs supported on the composite beams are finally cast into one composite structure which forms the load-bearing frame of the building. This increases, among other things, freedom in the design and manufacture of partitions and facades. At the same time, the subsequent renovation of buildings 20 will be facilitated, especially when the composite structures are supported by pillars.

Finnish patent number 93382 discloses one known composite beam and its various applications. The composite beam in question consists of a profile sheet and a cast component formed therein. In addition, within the casting component, there are biasing elements> 9 for biasing the composite beam. The composite beam also has transverse steel bars attached to the cast component. The steel bars are mainly intended as reinforcing bars for the final casting of concrete in order to make the finished composite structure as uniform as possible.

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The federated beam applications disclosed in said patent are very high. Thus, when the casting component is filled, the entire profile section is also formed by composite beams. In this case, handling them 35 both in manufacturing and on site in particular requires a robust lift. Raising the profile section will, of course, achieve rigidity in the composite beam, but at the same time the height will make it difficult for 2,107556 for example piping. Usually it is necessary to move the piping over or under the composite beam because it is too laborious to make the penetration into the composite beam. In addition to the high profile section, the composite beam has prestressing elements, however, insufficient for making long composite joists. In addition, despite the special clamping bars, the final bonding of the composite beam is poor because it is based on only a few steel bars. Adherence is also weakened by the smooth outer surface of the composite beam. On the other hand, the pre-installed clamps make the transport and handling of the composite beam 10 more difficult. It is also difficult to fit the composite beam to the pillars or other supporting structures.

FI patent application 980993 discloses a chin beam which is completely filled by pre-casting the profile part. In addition, the bar beam has 15 rarely placed tubes through which seam steels can be threaded. The jaw is high, heavy and laborious to manufacture. FI patent application 912353 discloses a steel concrete beam, which is also high. However, the pre-cast only partially fills the beam. Due to the shape of the beam and the small size of the holes, penetration of 20 concrete is uncertain. FI Publication No. 94451 discloses a composite bar which, however, does not have a pre-cast. In the SE announcement 461800, the beam is made of concrete profiles which are joined together by a concrete molding of the beam as a whole. This makes the bar high and 25 heavy.

The object of the invention is to provide a tensioned composite beam which is lighter but still more rigid and which provides a durable composite structure by simple work-sport. Characteristic features of the present invention will be apparent from the appended claims. The shaped profile portion of the composite beam according to the invention enables a secure engagement with the composite structure. In addition, the proportion of pre-casting is lower than before due to enhanced interaction between it and the profile section. In this case, the composite beam 35 to be installed is lighter but considerably stiffer. When installed, the composite beam is then an integral part of the composite structure without limiting the floor height. The composite beam according to the invention consists in practice of prefabricated steel parts, whereby the composite beam is also inexpensive and quick to manufacture, especially in serial production.

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The invention will now be described in detail with reference to the accompanying drawings illustrating some embodiments of the invention, in which: Figure 1 is a cross-sectional view of a finished composite structure formed by a composite beam according to the invention;

Figure 2 shows a profile section of a composite beam in accordance with the invention, cross-sectioned at the drainage opening; Figure 3 shows a profile section of Figure 2, added with tension and concrete steels,

Figure 4 is a cross-sectional view of a finished composite beam with the profile section modified;

Fig. 5 is an axonometric view of a composite beam in a column installation, partially sectioned.

Figure 1 shows a composite structure formed by a composite beam according to the invention. Other alternatives, such as concrete or steel composite slabs known per se, are also possible with composite beams. However, prestressed hollow core slabs reach longer spans than the composite slabs and are now widely used. During installation, the cavity slabs 10 are supported by the beams 11 of the composite beam. In the composite beam of the invention, the projections of _____ 30 are very thin, so that they do not limit the height of the layer. The actual hollow core bearing joint is formed together with the joint beam and the concrete casting 12. This makes the composite structure extremely durable and fire safe.

V 35 The composite beam itself includes a profile part 13 and a pre-casting 14 formed therein. In addition, the pre-casting 14 includes tendon and 4 107556 concrete steels 15 and 16, whereby a rigid composite beam is achieved. According to the invention, the tension and concrete steels 15 and 16 inserted into the composite beam are prefabricated. The structure of the steels is explained in more detail in connection with Figures 2 and 3. The tendon and be-5 toner steels 15 and 16 are further connected to the profile part 13 by transverse pins 17 and a prestress 14. In this way, the composite beam members are tightly engaged with each other, whereby the finished composite beam is advantageously rigid. Due to the novel structure of the profile section 13, the pre-casting 14 only partially fills the section section 10 in height. All in all, the proportion of pre-casting is significantly lower than usual, which reduces the weight of the composite beam. This, in turn, facilitates the handling of the beam both during manufacture and on site.

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As shown, the profile portion 13 is mainly formed of cut metal plates 18. In addition, the metal plates 18 are disposed on one side at an angle of 110 ° to 160 °, more preferably 120 ° to 140 °. The profile part is thus a kind of triangular structure 20 which achieves a sufficiently high profile and thus rigidity in the composite beam. The metal plates are cut so that they are not uniform but have holes. The finished composite beams then form drain holes 19, which are particularly evident from Figure 5. The metal plates are preferably cut with a tooth pattern 25 from one of the metal slits, so that the sheet material is not wasted. When making the profile part, the teeth formed during the surgery are aligned, whereby the tooth spaces form the openings. Preferably, the straight metal sheet portion covers about half the length of the composite beam, thereby providing sufficient large drainage holes 30 without compromising the stiffness of the composite beam. The drainage holes also improve the adhesion of the composite beam to the composite structure.

Preferably, the metal sheets are uniform, having two pieces. This avoids making splices. Sheet metal; : 35 can be smooth or, for example, a so-called rib plate. As shown in Fig. 2, the metal plate 18 is folded in such a manner that at the same time the edge projections 11 107556 are formed. Alternatively, the angle plates 20 (Fig. 4) are attached to the metal plates. This makes machining of metal sheets easier and the stiffness of the angles is better than that of metal sheets. On the other hand, the 5 angle brackets should be attached separately to the metal plates. In Fig. 4, the metal plates are welded directly to each other without a thick brush blade inserted.

When making the profile part, the cut metal plates are fixed by welding. Individual welds are not shown. In the embodiment of Figure 2, the metal plates 18 are secured to one another through a thick brushed steel 21. The continuous brush steel 21 extends over the entire length of the profile section 13. At certain intervals, the metal plates 18 are supported by upright narrow flat bars 22 which are also secured by welding. On the narrow flat bars 22 are attached second longitudinal and wider flat bars 23. These extend over a plurality of narrow flat bars 22 and are numerous over the length of the long profile portion 13. At suitable locations, there is a third flat iron 24 between the wide flat iron 23 and the thick brush steel 21. However, these flat bars do not extend over the entire length of the composite beam, mainly only at the columns. All in all, the profile section alone is a rigid assembly that is preferably manufactured at a site other than a concrete factory. This makes it possible to utilize the machines and 25 skills of the metal workshop. In addition, side brush steels 25 are secured inside the profile section.

In addition to the profile section, the concrete and tension steels used in the composite beam are also prefabricated. The essential steels 15 uniformly extending throughout the composite beam are preferably arranged in two layers. Generally, there are 12 to 28, more preferably 16 to 24, tendon steels in each layer per meter of width of the pre-casting. In the embodiments shown, the tensile steels 15 are assembled into three bundles of i (35 eight tensile steels. The bundles are easy to handle and can be varied in number as required by 6 107556). In addition to the concrete reinforcing bars shown, there are special splitting steels (not shown) particularly at the end of the composite beam, which effectively prevent longitudinal cracks in the ends.

Accordingly, all steel members 10 in the composite beam are preferably prefabricated. Only the actual assembly and pre-casting is done at the concrete plant. The manufacture of the composite beam begins by placing the uniform tension steels on a casting substrate (not shown) and tensioning them to a suitable tightness with a suitable device. Next, the reinforcing steels 15 are secured with reinforcing steels. Thereafter, the prestressed section section is superimposed on the tension steels. Finally, the steel parts are secured together with dowels. The dowels are preferably threaded rods with nuts 26 and washers disposed between the ledges to determine the width of the profile section.

Alternatively, the dowels may be metal bars with suitable threaded sections for their nuts. In this case, the width of the composite beam can be precisely adjusted and it can also be tensioned laterally. At the ends of the composite beam ·., The number of threaded rods is 6 to 14, more preferably 8 to 12 for every 25 meters of length of the composite beam. Elsewhere in the composite beam, there are threaded rods every 1000 mm.

Finally, a pre-casting is cast inside the tightened profile section. The profile part also acts as a mold. Pre-casting is done .... 30 through the drain holes. After the pre-casting has dried, the clamping devices are removed and the composite beam is ready for installation. In the finished composite structure, the concrete casting then fills the rest of the profile section. In this case, the profile portion is largely left inside the concrete casting, which provides excellent adhesion.

·. 35 The reinforcing steels also include meshes 27 on the inside of the profile section, which are fitted to the pre-casting 14 extending partially above it 7107556. Depending on the application, the meshes may also extend from the drain holes above the profile section. Mesh nets help to improve adhesion and thus increase the cutting capacity of the composite beam.

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If desired, openings may be left in the pre-casting, for example for vertical penetration. Preferably, the pre-casting is provided with vertical openings 28 at pre-selected casting openings. The tendon steels are also positioned with respect to the openings 10 (Figure 4). The openings are usually for pillar infestations or the like supporting a composite structure. Such an embodiment is shown in Figure 5. Here, the threaded rods 31 of the pillar 29 are easily guided through the openings 28. The end of the lower pillar 29 rests on the underside of the foreward 14. The columns 29 and 29 'are set to the right height by means of nuts 30. The final concrete casting covers the junction of the columns 29 and 29 ', which further increases the strength of the composite structure. Thus, the pillar adhesions remain inside the concrete casting, which eliminates the need for separate soldering. Before the concrete is poured through the openings, wiring or piping can simply be conducted (dashed line in Figure 1). The cavities of the cavity slabs can also be easily utilized. The composite beam of Fig. 5 differs slightly from that described above.

♦ 25 The composite beam according to the invention is particularly light but stiff and not cracked. In addition, the composite beam does not require separate fire protection. One of the composite beams of the invention has a mass of about 230 kg, but nevertheless can easily exceed 20 meters in length. The width of the Ta-30 conventional composite beam is approximately 800 mm, of which 600 mm is pre-cast. At the same time, the overall height of the composite beam is less than 300 mm, of which about one third is pre-casting. Naturally, the dimensions of the composite bar vary from application to application. In general, the composite beam according to the invention is light but stiff and; - 35 durable. In this case, long and continuous composite beams can be produced advantageously, which significantly speeds up the installation and construction work. Multiple pillars can support one long composite beam, resulting in a multi-hole continuous structure. In addition, the composite beam is inexpensive and quick to manufacture. Most importantly, however, the end result is a durable composite structure, 5 which can be easily and simply made through the necessary penetrations and reinforcement. The profile section, mesh anchors anchored in tensioned pre-casting, and the seam steels of the tile elements ensure a constructive interaction in the final composite structure.

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Claims (11)

A tensioned composite beam for use with prefabricated slabs (10) or composite panels to form a composite structure 5, particularly in roofs, ceilings or intermediate floors of buildings, comprising a prefabricated profile part (13) provided with drainage openings (19) and formed therein; pre-casting (14) partially filling the profile part (13) and internal tendon and concrete steels (15, 16) of the pre-casting (14), wherein, when installed, the composite beam is adapted to support the preforms (10) or concrete casting (12) connecting the composite structure, characterized in that the profile part (13) has transverse dowels (17) 15 provided with nuts (26) for prestressing the profile part (13), and prefabricated tension and concrete steels (15, 16). is connected to the profile part (13) and the studs (17) by said pre-casting (14). Composite beam according to Claim 1, characterized in that the profile part (13) is mainly formed of cut metal plates (18) which are placed on one side at an angle of 110 ° to 160 °, more preferably 120 ° to 140 °. Composite beam according to Claim 2, characterized in that there are two pieces of metal plates (18) and fastening angles (20) forming said edge projections (11). Composite beam according to one of Claims 1 to 3, characterized in that the tension steels (15) extending substantially uniformly over the entire length of the composite beam are preferably arranged in two layers. Composite beam according to Claim 4, characterized in that there are 12 to 28, 10 107556 tension steels (15) in each layer, preferably 16 to 24 per meter of width of the pre-casting (14). Composite beam according to one of Claims 1 to 5, characterized in that the studs (17) are threaded rods with nuts (26) and washers disposed between the edge projections (11) to determine the width of the profile part (13). A composite beam according to claim 6, characterized in that the end portions of the composite beam have 6 to 14, more preferably 8 to 12, threads per meter of length of the composite beam. Composite beam according to one of Claims 1 to 7, characterized in that the pre-casting (14) is arranged to be performed through the openings (19), the concrete casting (12) of the composite structure being arranged to fill the profile part (13). A composite beam according to any one of claims 1 to 8, characterized in that the composite beam comprises meshes (27) fitted to the pre-casting (14) extending partially above it. 9 107556 A composite beam according to any one of claims 1 to 9, characterized in that vertical openings (28) are provided at the pre-casting (14) at the pre-selected casting openings (19) for supporting the column structure or similar. 11 107556