FI85745C - Fireproof prefabricated steel beam - Google Patents

Abstract

The invention relates to a fire-resistant prefabricated steel beam arranged to act together with concrete as a load-bearing jointing construction for various slabs. The beam comprises two web portions and horizontally projecting flange portions extending beyond the web portions. To achieve a simple beam easy to install at least each web portion (2) with its horizontally projecting flange portion (1) is formed by an integral material strip so that the web portion (2) and the projecting flange portion adjoining it form a jointless entity and so that the web portion (2) is in a slanting position with respect to the flange portion. The web portions (2) are arranged side by side so as to slant towards each other and interconnected at edges closer to each other by means of a horizontal upper part (3). The edges of the web portions (2) farther apart from each other are interconnected by means of a plate (4) welded to the web portions. Openings (14) are formed close to the upper edges of the web portions (2) and/or in the horizontal upper part (3) to fill the space defined between the upper part (3) of the web portions (2) and the plate (4) with concrete in a manner known per se.

Description

1 85745

Fireproof prefabricated steel beam

The invention relates to a refractory prefabricated steel beam 5 which is adapted to co-operate with concrete as a load-bearing joint structure of various slabs and which comprises two web parts and horizontal projecting flange parts extending beyond them.

The frame of a prefabricated building is often formed by intermediate and upper bases made of trusses and beams. In order to make the beams as load-bearing horizontal structures sufficiently rigid, their height as reinforced concrete structures is about 500 to 800 mm. For heating, plumbing, air conditioning and electrical installations, the beams must be torn or the height of the subfloor structure must be increased. The high beam structure has in some cases been replaced by a jaw-beam structure, leaving the web of the beam inside the midsole structure. The height of the jaw beam has been minimized by using e.g. tensioning. From a manufacturing point of view, the jaw beam 20 is more difficult to manufacture than a normal beam, and the minimum thickness of the jaw is still 100 to 150 mm.

Prizes are often also made of steel. A steel beam is easier to manufacture than a precast concrete beam and is easy to transport and install. In addition, it is easier to carry out 25 modifications on site to a steel beam. Because steel beams do not require post-casting and are light to move, the installation speed of the beams is higher than when using concrete beams. By adapting the construction to the frame erection schedule, the total construction time can be shortened. In the event of a fire, the steel loses its strength as the temperature rises, so the steel beam must be fire-protected. The fire protection is most preferably provided by embedding the steel profile in a concrete subfloor structure, in which case only the lower flange has had to be protected. Fire barn and is made either by covering the lower flange-35 pa with a fire protection plate, insulation, paint or spraying 2 85745. In addition, for aesthetic reasons, the piping and fire protection are often covered with a so-called lowered roof.

The fire protection method has led to the use of a low hat profile, about the height of the midsole element, in which the lower flange of the straight-5 rail-shaped base beam is wider than the other beam, while forming projections for the midsole elements. Because the structure remains low, steel cannot be optimally utilized in terms of structural rigidity. Despite the extra steel pounds, the hat beam (THQ beam) 10 has been used quite often, for example in commercial buildings, where it is desired to make efficient use of the building volume by means of a low midsole structure. With the help of the low midsole structure, considerable savings have also been achieved in special cases, when, for example, in urban construction 15, the establishment depth would otherwise have had to be increased and thus e.g. to support the foundations of neighboring houses.

The use of a steel beam has been limited mainly by the exciting li. At long spans, the beam structure has become quite heavy and it has been necessary to prepare the beams with pre-raises to eliminate deflections. As construction work becomes more and more expensive, it is now desired to make buildings so that the purpose can be easily changed later. With long midsole elements and few support structures, such easy versatility is achieved by displacing the bulkheads. From a manufacturing point of view, the handling of long beams is difficult, according to the span dimension, it is necessary to get a pre-increase of straw despite the thermal stresses caused by welding, and as the plate thicknesses increase, the welding work slows down.

Em. In order to eliminate the drawbacks, it is now proposed to create a composite steel beam-concrete. An example of such solutions is the solution described in FI patent application 882186. With the help of the joint structure, a lighter steel beam is achieved and the beam can be used at even longer spans. E-application by. With its steel beam 882186, welding work has been saved by forming 3 85745 beams from parts of the profile which have already been hot-rolled into shape. However, the solution according to FI application 882186 is complicated from the point of view of manufacturing, since the intermediate pieces 5, which create a joint effect, increase the welding work and complicate the manufacture of the beam with regard to the handling of several small pieces.

The object of the invention is to provide a steel beam working with concrete, by means of which the disadvantages of the prior art can be eliminated. This has been achieved by means of a beam according to the invention, which is characterized in that at least each web part and the horizontal protruding flange portion extending beyond the web portion is formed of a unitary strip of material such that the web portion and the associated protruding flange portion form a seamless assembly and the web portion is inclined with respect to the flange portion, the web portions being aligned adjacent to each other in position and connected to each other by means of a horizontal top by means of a horizontal top, and by means of a plate welded to the web portions at the distal edges of the web portions 20 and that openings are formed . As for the advantages of the invention, it can be said in general that it has managed to retain all the previously mentioned good properties of a steel beam, i.e. easy adaptability to the site frame system, low and light structure, quick installation, simple HVAC installations, etc. benefits.

The beam according to the invention is designed so that its steel parts carry the loads of the slab elements during installation. In connection with the joint casting of the slab elements, the housing formed by the steel beam and the gap formed by the road of the slab element-35 and the steel profile are filled. In the finished structure 4 85745, the beam according to the invention carries the loads acting on it by means of a joint effect between concrete and steel. The beam is also suitable for use in conjunction with a stationary cast tile. In this case, both the slab 5 and the beam can be concreted in one step. The beam according to the invention can be made from a manufacturing technique on an automatic line by optimizing the required welding work according to the required rigidity. The web members can simply be perforated to provide a composite effect. The protrusions that may be left in the edges of the holes or openings made in the web parts when perforating will increase the co-operation between the concrete and the steel. The openings are located, for example, at the top of the oblique web parts, so that the post-cast concrete enters the beam without difficulty. In addition, the oblique web parts of the beam 15 make it possible to place the slab elements just in the fold of the cantilever parts without interfering with the post-casting. Em. for this reason, the stresses on the jaw remain smaller than in solutions in which a separate casting space has to be left between the slab element and the vertical web part of the beam. In the event of a fire, the preferred shape, together with the joint casting of the midsole elements, wedges the slab into place, leaving the beam cantilever flanges only for the installation of the elements. The draw flange of the beam, which is placed inside the profile, can be pre-fireproofed during the manufacture of the beam element 25 without increasing the height of the intermediate floor structure. The cantilever flanges protect the fire protection layer during transport and installation. The fire protection layer can also be protected from mechanical wear and damage by means of a thin plate attached to the cantilever flanges.

The invention will be explained with reference to the preferred embodiments shown in the accompanying drawing, in which Figure 1 shows a cross-section of a beam according to the invention, Fig. Fig. 5 shows a second embodiment of a beam according to the invention in a cross-sectional view, Fig. 6 shows a block diagram of an automated production line of a beam according to the invention, and Fig. 7 shows a third embodiment of a beam according to the invention.

Figure 1 shows a cross-section of a beam according to the invention in a situation where the slabs are mounted on a beam and the concrete is cast inside the beam and between the beam and the slabs. The beam according to Figure 1 is formed by making each web part 2 and the associated horizontal projection flange 1 from a uniform strip of material. The web parts 2 are in an oblique position with respect to the cantilever flanges 20 1. One of the joints comprising the web part 2 and the cantilever flange part 1 can be made, for example, by bending from suitable steel counters.

The units comprising the web part 2 and the cantilever flange 1 are arranged side by side so that the web parts are inclined towards each other 25 and connected to each other by means of a horizontal upper part 3 by means of a horizontal top 3. The horizontal top part 3 can be formed from a separate strip of material, for example a strip of steel, which is welded to the upper edges of the web parts.

Thus, in the embodiment according to Figure 1, each unit comprising the web part 2 and the cantilever flange part 1 is completely seamless.

Between the distal edges of the web parts 2, a horizontal steel plate 4 is welded so that it 35 acts both as a mold below the concrete 8 6 85745 to be cast inside the base profile and as a lower flange bearing the load of the beam. In the example of the figure, the plate 4 is placed higher than the level of the lower surfaces of the cantilever flanges 1. Em. the arrangement allows the beam to be fire protected without increasing the structural thickness of 10.

Shoulders 12 can be stamped on the inclined web parts in the inclined position of the beam, on which the plate 4, which acts as a lower flange, rests during the welding work.

10 In order to fill the beam with concrete, openings or holes 14 are made in the web parts 2 in an oblique position. In order to ensure a joint effect between the steel and the concrete, spike-like or plate-like projections 5 are formed on the edges of the openings 14, for example during manufacture.

From the top of the beam, steel suspension bars and 6 are led to the bottom of the supporting slabs, which increase the ability of the beam to support the slab together with the wedge-shaped concrete part 7 formed outside the beam 20 during concreting. In addition to the suspension bars 6, gripping hooks 18 can also be used, which effectively anchor the wedge-shaped concrete part 7 in place. In order to increase the rigidity of the beam during installation, the steel surface area of the upper surface can be increased by means of a steel plate 9 or reinforcing bars welded below or above the upper part of the base profile 25. The use of reinforcing bars improves joint performance.

During the installation phase before installing the slab, the beam is supported in the middle of the structures below. The central support is removed when the post-casting has reached sufficient strength. The time support ensures efficient joint operation, which reduces both the in-construction and post-construction deflection and thus the need for pre-raising. The support substantially reduce the burden caused by the temporary installation 35 of the compression side the need for the amount of steel.

7 85745

Figure 2 is a side view of the beam of Figure 1. The openings in the web parts 2 of the beam are located so that no cavities are formed under the horizontal top 3 of the beam during concreting. The openings 14 5 are located in the web parts 2 in the vicinity of the upper edges. The openings 14 can also be used for the penetration of slab field reinforcements as well as HVAC pipes.

Figure 3 shows the connection of the beam according to Figures 1 and 2 to a load-bearing vertical structure, i.e. a column.

10 The end of the beam is shaped so that the beam support (pillar bracket) 11 fits completely inside the beam. The beam is supported on the console from its horizontal top acting as an upper flange and tightened with mounting bolts 13 from the side of the beam to the side of the console. Mounting-15 wedges can also be used for tightening. This ensures the torsional rigidity of the beam during installation. A support moment is created in the joint beam by installing concrete reinforcement on the support through 15 brackets before post-casting the joint. The support moment reduces the deformation of the beam and increases the load-bearing capacity. Another step 20 to provide a support torque is shown in Figure 4. Through the column, drawbars 16 are inserted, which are fastened to the end of the beam by means of tightening nuts 17. The nuts are tightened through the opening 14 in the web part of the beam.

Figure 5 shows another embodiment of a beam 25 according to the invention. In this embodiment, the beam is already concreted during the manufacture of the beam. In this case, a conventional prestressing technique for concrete beams can be used for the beam to increase the bending capacity of the beam. The degree of prestress may be higher than usual, as the steel profile surrounding the be-30 pushes effectively limits the cracking of the concrete, thus acting as a kind of hook reinforcement. In the embodiment of Figure 5, the beam may be provided with openings or holes 20 in the horizontal upper part 3, through which concrete 21 is poured into the interior of the beam. Protrusions 22 8 85745 may be formed on the edges of the openings 35 or holes 20 as described above in connection with the projections 5 of the openings 14. The structure of the beam of the embodiment of Figure 5 corresponds in other respects to the embodiment of Figure 1.

In the embodiment of Figure 5, no additional steels are required for the upper surface of the beam 5, since the beam already functions as a composite structure when installed. When the beam is bent, the plate 4 takes the tensile stress and the compressive stresses at the top of the concrete filling of the beam.

The shape of the beam according to the invention enables its efficient production on an automatic production line. Figure 6 is a block diagram of a beam manufacturing line. The shape of the beam is achieved, for example, by bending a thin steel plate. The holes are pierced with suitable means, for example in the web parts. In connection with the piercing, protrusions that improve the joint effect are also formed in the same work step. The parts are sawn to size and any pre-raising is made according to the span of the beam. The cut-to-size top, the possible additional steel of the top and the plate acting as a bottom flange are pre-raised to the shape corresponding to the profile. The welding of additional steels can be easily carried out by a blow-drying machine as a powder arc welding from the welding rails formed at the corners of the steel plates. The details of the beam head are welded as robot welding. Finally, the beam is coated and the fire protection is distributed as required.

Figure 7 shows a third embodiment of the invention. The embodiment of Fig. 7 differs from the embodiment of Figs. 1 and 2 in that in the embodiment of Fig. 7 the outer flange parts 31, the web parts 32 and the upper part 33 are formed from a uniform basic profile. Em. the basic profile can be formed, for example, from a cold-formed profile. In this embodiment, the assembly of the cantilever flange portions 31, the web portions 32 and the top portion 33 is completely seamless. In other respects, the embodiment of Figure 7 corresponds to the embodiment of Figure 5. The slab acting as a lower flange is described by reference number 35 34, holes by number 40, projections by number 42 and shoulders 9 by 85745 by number 32. Concrete is marked by number 41.

The above examples are not intended to limit the invention in any way, but the invention can be modified completely freely within the scope of the claims. Thus, it is clear that the beam according to the invention or its details do not have to be exactly as shown in the figures, but other alternatives are possible.

Claims (6)

1. Fireproof prefabricated frame beam which is arranged to cooperate with concrete as a supporting composite structure in 5 different tile systems and comprising two life sections and beyond these extending horizontal projection flange sections, characterized in that at least each life section (2,32) adjacent to the respective life section, outside the horizontal extending flange section (1,31) extending there is formed by a uniform material strip, so that the life section (2) and the adjacent projection flange section (1) form a seamless whole. -and say that the life section (2.32) is inclined towards the flange section, that the life sections (2) are arranged next to each other so that they are in a mutually inclined position and are connected to one another at their proximity to one another. edges by means of a horizontal upper part (3.33), and by means of a plate (4.34) which is welded in the life sections at the life sections (2.32) further away from each other, located adjacent to the projection flange sections (1.31), and that openings (14,20,40) for the upper edges or / and in the horizontal upper part (3.33) have been machined for filling the space as the upper part (2.32) of the upper section (2.33) and the plate (4.34) delimit with concrete in a manner known per se. 2. An adjustable beam according to claim 1, characterized in that the adjacent edges of the life sections (2) are connected to each other by means of an upper part (3) formed by a separate strip of material. 3. An adjustable beam according to claim 1, characterized in that the life sections (32), the projection flange sections (31) and the horizontal upper part (33) are formed by a uniform basic profile. 4. An adjustable beam according to claim 1, 2 or 3, characterized in that the edges of the openings (14,20,40) have been designed from the life section (2,32) to ensure the composite effect of concrete and frame. or the planar protrusion of the upper part (3.33) (5.22.42). 5. An adjustable beam according to any of the preceding claims, characterized in that the plate (4.34) connecting the lower edges of the life sections (2.32) is arranged higher up than the plane of the lower surfaces of the projection flange sections (1.31). 6. An adjustable beam according to any of the preceding claims, characterized in that in the horizontal upper part (3.33), at least one superfluous support plate (9) or / and a concrete iron has been fixed.