The invention relates to a building method, comprising placing columns in a rectangular grid arrangement, fixing to said columns horizontal supporting elements, and placing concrete floors which are supported by said supporting elements.

Such a method was devised by Geilinger A.G. in Switzerland. This firm described the building system in question in leaflets and acquired European Patent No. 0044271 for details of the system. In general, the columns are made of steel, although concrete columns are not ruled out. According to the known building system, the concrete floors are poured on the spot and supported on crowns fixed to the columns. Either ordinary wooden forms or prefabricated forms approximately 5 cm thick are fixed below the crowns here. The floor formwork is supported by means of yokes which bear on the set floor underneath them. A floor approximately 22 to 27 cm thick is poured on the skins. The major disadvantages of this system are: that setting and supporting of the concrete floors takes so much time that building speed is lower than the speed corresponding to erecting the steel structure; that facilities such as ventilation ducts, electricity cables and computer cables have to be accommodated in separate spaces under the concrete floor, so that the total thickness of floor and facility space is great, and the height of the storey is also consequently great; that pouring concrete floors on the spot is unpopular, dirty work; that when there is heavy rain and/or frost no concrete can be poured. The object of the invention is to avoid these disadvantages, and to this end the building method mentioned in the preamble is characterized in that the above-mentioned supporting elements form a system of girders each provided with a number of adjacent, spaced feed-through conduits, in that the floors are made of prefabricated hollow floor elements, each having a bottom sheet, a top sheet and spacers arranged in a grid shape placed between them, the bottom sheet of each floor element having at two opposite sides laterially

projections parts, and in that in order to fix the floor elements, they are raised tintil the above-mentioned projecting . parts lie against the girders, following which said projecting parts are connected to the girders.

The feed-through conduits are used for feeding through lines and cables.

The floor elements are rectangular and are fixed solely by their short sides to the girders. If the girders are steel section beams, they will have to (and/or can) be protected against fire. In a preferred building method the rows of spacers adjacent to the projecting parts project between the feed-through conduits of the girders, while concrete is poured in the spaces bounded by the external surface of the feed-through conduits and the end faces of the spacers projecting between the feed-through conduits.

An excellent connection between the floor elements and the girders is obtained through the end faces of the spacers projecting between the feed-through conduits being made step- shaped in such a way that the space between two opposite spacers widens out step-shaped from top to bottom.

The girders are preferably steel I beams.

The steel beams can also be channel beams, in which case a reinforced concrete is placed in the channel beam. In the case of relatively high floors, the beams can comprise two tilted channel beams held apart by transverse conduits, and the space between said beams is filled with concrete.

It is important that the reinforcement of the concrete floor elements should not be prestressed. This avoids concave or convex surfaces of the floors.

In order to ensure that the hollow between- the top and bottom sheet of the floor elements can be reached easily, the top sheet is provided with apertures which are placed in a grid arrangement and can be covered with tile-type sheets abutting each other.

The invention will now be explained in greater detail with

reference to the figures, in which three examples of embodiments are shown.

Figure 1 shows a perspective view of a part of a structure built according to the invention, for the sake of clarity parts of - some floor elements being shown partially cut away.

Figure 2 is a section along the line II-II in Figure 1.

Figure 3 s a section along the line III-III in Fig. 1.

Figure 4 is a section along the line IV-IV in Figure 1.

Figure 5 shows a section comparable to that of Figure 4 of an alternative girder design.

Figure 6 shows a perspective view of a structure in which the preferred method according to the invention is used.

Figure 7 shows a section along the line VII-VII in Figure 6.

The structure shown comprises a number of columns 1, preferably of steel, placed in a rectangular grid arrangement. At each column a number of crowns 2 are placed above one another. The vertical distance between the crowns corresponds to the height of storey. Since such a system is known per se, only one column with one crown is shown in Figure 1. The invention is concerned with the way in which prefabricated floor elements are supported relative to the columns 1. The prefabricated floor elements are of dimensions of, for example, 720 x 240 cm.

In the invention according to Figures 1 - 4, girders in the form of steel channel beams 3 are fixed between the crowns 2 situated at the same level. These beams run parallel to each other, and their lengthwise direction coincides with the direction of the transverse edges of the prefabricated concrete floor elements which are fixed to the channel beams and will be described in greater detail below.

Each floor element comprises a bottom sheet 4, a top sheet 5, and fitted between said sheets spacers 6 in the form of lobes which are moulded onto the bottom face of the ^• top sheet and are in a grid arrangement. The bottom sheet 4 is anchored to the lobes 6 through reinforcement ties 7 being concreted into the lobes and projecting at the bottom side, and being forced into the concrete of the

bottom sheet before this concrete is set.

Figure 1 shows the bottom sheet 4 of a first floor element without top sheet and the bottom sheet 4 with top sheet 5 of the second floor element. The top sheet is provided with apertures 8 placed in a grid arrangement and covered with tile-shaped sheets

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It can be seen from Figure 4 that the top sheets 5 at the transverse edges of the floor elements abut one leg of a channel beam 3, while the bottom sheets 4 at their transverse edges project under the body of a channel beam 4 at 4a up to the transverse edge of the bottom sheet 4 of another floor element.

When being fitted, the floor elements are raised until the projecting parts 4a rest against the girders 20.

These parts 4a of the bottom sheet lying under the body of a channel beam are fixed to the body by means of bolts. The bolts are shown schematically in Figure 4 by dotted and dashed lines 10.

At the position of each crown 2, a recess is provided in the corners of a floor element, into which recess a part of the crown fits. The channel beams 3 are provided with transverse feed- through conduits 11 which open out into apertures 12 in the legs of the beams 3, an which serve to carry lines or cables from a hollow space of one floor element through the channel beams 3 to the hollow space of another floor element. Reinforced concrete is poured into the channel beams, so that the channel beams serve as permanent falsework. If the channel beams are destroyed by fire, the concrete remains in place.

The embodiment shown in Figure 5 is intended for higher ' floors. Instead of a channel beam 3, use is made of two channel beams 13 which are tilted through 90°, and between which transverse conduits 11 are welded, which conduits open out into openings in the body of the channel beams 13- Lock-woven mesh is placed in the space between the channel beams 13 and concrete is poured. The top sheets 5 are provided at their transverse edges with projecting reinforcement irons 14, the projecting part of which is embedded in the concrete between the channel beams 13-

In the case of the building method illustrated in Figures 6 and 7, t e girders are in the form of I beams 20 which are fixed to the columns 1 without crowns between them. The hollow floor elements, comprising a bottom sheet 4, a top sheet 5, an spacers 6 placed in a grid arrangement between said sheets are fixed at their transverse end edges to the I beams 20 through the projecting parts 4a of the bottom sheet 4 being engaged with the bottom flange of the I beams and fixed by bolts 10 when the floor elements are raised. The rows of spacers 6a adjacent to the projecting bottom sheet parts 4a are made elongated and project between the feed- through conduits 11. Concrete is poured into the spaces 21 bounded by the outer surface of the feed-through conduits and the end faces 6b of the spacers 6, so that the I beams 20 and the conduits 11 are completely embedded in concrete. This greatly improves fire safety. Because the end faces 6b of the spacers 6a are made step- shaped in such a way that the space between two opposite spacers 6a widens out downwards in a step shape, an excellent connection is also produced between the spacers 6a and the girders 20. The seams between the bottom sheets 4 of the floor elements are sealed with a sealer or shaped metal strip.

All kinds of facilities, including those in the field of heating, ventilation, electricity, telephone, computers, can be accommodated in the hollow floor elements, so that a separate space for these underneath the floor is not necessary. The storey height of a building can be limited as a result of this. After the fitting of a floor, it is possible to start immediately on the fitting of the next floor, which means that building can be speeded up considerably compared with a building system in which the floors are poured on the spot. It is possible to work immediately on each fitted floor, since there is no need to wait for setting and there are no supports on it for the next floor. If there are steel columns, they are enclosed with fire-resistant material.