Floor structure element Field of the invention The invention relates to a floor structure element provided with two opposite bearing ends between which extends a floor and at least two joists, intended to support the floor and arranged at a distance from each other, in accordance with the preamble of claim 1. The invention also relates to a method of manufacturing a floor structure element where a reinforcing construction intended for the floor of the floor structure element is placed into a mould and cast into concrete in accordance with the preamble of claim 9.

State of the art During the production of multi-storey buildings it is usual to make moulds and after performing the reinforcing, to cast the different floor structure elements on site. This method leads to a slow and complicated construction. With the object of simplifying construction different types of prefabricated floor structure elements, usually made of concrete, are used which are placed on supporting walls which are often cast on site. Such floor structure elements generally suffer from the disadvantage that they have low dimensional accuracy, which in combination with the low dimensional accuracy in the rest of the construction means that comprehensive finishing, for example to make the floors smooth, is required. The design also means that the weights become high leading to more difficult handling and greater demands on the other supporting parts as a consequence. Through the production in general being directed to a small number of standard types, the flexibility in design of buildings is reduced.

Objects of the invention The invention aims to provide a floor structure element which simplifies construc- tion and which is easy to fabricate with good dimensional accuracy with different

designs. This floor structure element shall also, despite a relatively low weight, have good stiffness and permit good flexibility in the construction.

Disclosure of the invention These aims are achieved according to the invention with the help of a floor structure element, where the floor is delimited at the sides by a frame made from metal pro- files, to the opposing short sides of which the ends of the joists made of metal are attached and where the floor is made of concrete, which is cast on site into the frame and encloses a reinforcing construction attached in advance all around the frame, in accordance with the characterizing part of claim 1.

Through using a metal frame and joists made of metal in a reinforced concrete floor the floor structure element can be made with extremely good dimensional accuracy at the same time as it can be made stiff but evenso relatively light.

Depending on the size of the floor structure element the number ofjoists can be varied and it is also possible to select different types ofjoists. They can, for example, be of the I-profile type but can also be of the truss type. A relatively large web height in the joists gives plenty of room for horizontal installations between the ceiling on the underside of the joists and the floor on top of the joists. A floor structure element according to the invention can advantageously be made so that the reinforcing construction is attached to the sides of a frame made from metal profiles, where two joists made of metal which extend between the opposing short sides of the frame are attached to these short sides, whereafter the frame is placed with the joists facing upwards on a moulding table, which has a surface profile correspond- ing to that of the intended floor surface, whereafter the frame is filled with concrete in order to form a reinforced concrete floor between the joists and the moulding table. By means of this method, extremely well-defined edges are obtained on the floor structure element at the same time as an extremely smooth and flat floor surface can be obtained. This precision facilitates construction to a great degree.

Further characteristics and advantages of the invention are evident from the following description and claims.

Description of the figures The invention is explained more closely in the following with the help of examples shown on the accompanying drawings, where Fig. 1 shows a perspective view from below of a floor structure element according to the invention, Fig. 2 shows a perspective view from above of the floor structure element of Fig. 1, Fig. 3 shows a view from below of an end part of the floor structure element accord- ing to the invention mounted in a house, Fig. 4 shows a plan view of the floor in a storey of a multi-storey house, Fig. 5 shows a section V-V in Fig. 4, Fig. 6 shows a section VI-VI in Fig. 4, Fig. 7 shows in a simplified way how the reinforcing construction is formed in the floor structure element shown in Fig. 5 and Fig. 6, Fig. 8 shows a section VIII-VIII in Fig. 4, Fig. 9 shows schematically a section across the longitudinal direction of two floor structure elements, and Fig. 10 shows ajoint between the floor on two floor structure elements.

Description of preferred embodiments A floor structure element 1 shown in Fig. 1 and 2 according to the invention has two opposing bearing ends 2 and 3 between which extends a floor 4. Under the floor 4 are two joists 5 and 6 intended to support the floor 4 and arranged at a distance from each other, which extend the whole length of the floor. In this case the joists are mutually parallel but this does not necessarily have to be so.

The floor 4 has an edge formed by a frame 7 which in this case is rectangular and is made of metal profiles, where the side profiles 8 and 9 are joined by end profiles 10

and 11, in which the ends of the joists 5 and 6 are attached. The upper side of the frame 7 is level with the underside of the floor 4, and the upper side of the joists 5 and 6 is level with the underside of the floor 4, in order to be in contact with and support the floor. In order to produce good force transmission, particularly of shear forces, between floor and joists the latter are on their upper sides provided with a number of projecting coupling means 12, arranged at a distance from each other, which are intended to project into the underside of the floor 4.

The joists 5 and 6 are suitably made of metal and can have different designs. They can, for example, be of the I-profile type which is shown to the right of Figs. 1 and 2, but they can also be of the truss type, as is shown to the left in Figs. 1 and 2. Also other equivalent designs are naturally possible. The joists 5 and 6 suitably have the same design along the whole of their length and are made not in accordance with Figs. 1 and 2 where two types have been combined in order to show different possi- bilities.

The number, type and dimensions of the joists and their placement are naturally a function of the size and shape of the actual floor structure element.

A reinforcing construction 13 comprised in the floor 4 is attached to the different sides of the frame 7 by e.g. welding and is at a certain height above the upper side of the joists 5 and 6. The reinforcing construction 13 is in this case formed as a reinforcing net with the edges of the grids parallel with the joists 5 and 6, but other variants and orientations are naturally possible.

The upper side of the floor 4 normally is in the same plane over the whole of the floor structure element 1. In certain connections it can, however, be advantageous to make the floor structure element 1 with at least one local depression 14 where a part of the floor is lower than the rest of the floor. This will be explained in more detail later.

According to Fig. 3, which shows a floor structure element 1 mounted in a house, the joists 5 and 6 are each provided with one or more openings 15 in order to facilitate different types of horizontal installations in the floor structure between the floor 4 and a ceiling 16 able to be mounted on the underside of the joists 5 and 6.

A floor structure element 1 in accordance with the invention is intended to be supported on a suitable support construction at both its bearing ends 2 and 3, thereby using the end profiles 10 and 11 for supporting purposes. These end profiles, which suitably are U-shaped, are advantageously so powerfully dimensioned that the floor structure element 1 can be supported only at the comers. It is naturally also possible to use different forms of support between the ends on the end profiles 10 and 11.

The side profiles 8 and 9, which do not have such a large supporting function, can advantageously be thinner than the end profiles 10 and 11 and have a height which is lower than those. It is, however, important that the side profiles 8 and 9 are straight in order to permit a good fit with adjacent floor structure elements.

Fig. 4 shows schematically how it is possible, with different floor structure elements 1 in accordance with the invention, to form a storey 17 in a multi-storey house. The transition between different floor structure elements are shown with solid lines and the positions of the joists are shown with double, dashed lines.

The storey 17 has a central stairway 18 and a lift shaft 19 connected thereto. Walls separating apartments 20 and 21 divide the storey 17 into different apartments and form, like the stairway 18 and the lift shaft 19, support for one end ofthe different floor structure elements. The outer wall 22 of the house, formed of different elements, also forms a support for the ends of the floor structure elements.

One floor structure element 23 is designed to at one end support a separate, prefabricated wet room module 24 provided with its own floor and is therefore

provided with a depression 14 of the type shown in Fig. 2 corresponding to this floor and intended for the wet room module.

The design of this floor structure element 23 is shown more closely in Figs. 5-7.

A wet room module 24 has its own floor 25, which rests on a floor part 26 situated under the floor 4 and comprised in the floor structure element 23, which is formed integrally with the floor 4. As is schematically evident from Fig. 7, the reinforcing construction 13a, belonging to the floor part 26, is under the upper side of the joist 5, while the reinforcing construction 13 is above the joist 5. It is hereby suitable that the joist 5 has through-holes for the reinforcing rods comprises in the reinforcing construction 13a so that reinforcing over the whole width of the floor part 26 becomes possible at the same time as good fixing to the joists can be obtained.

As is indicated in Fig. 7, the end of a floor structure element is attached to a supporting construction, for example with the help of screwed joints 27.

Fig. 8 shows how two floor structure elements 1 are connected to a wall 28 with supporting pillars. A ceiling 16 is mounted on the joist 5 via support elements 29 and forms a support for an insulating layer 30.

Fig. 9 shows how a normal floor structure appears in section. By forming the floor structure elements according to the invention it is possible to immediately achieve an extremely even upper side 31 of the floor 4. Only a seam 32 between two adja- cent floor structure elements can require a certain a certain filling before covering is performed with the desired material, without requiring the usual filling of the concrete surfaces.

A possible way to form a seam 32 between two floor structure elements is shown in fig. 10, where the side profiles 8 and 9 have been given a special shape in order to permit the use of a seal 33, which before mounting of the floor structure elements

suitably can be attached to the ends of these. Variations on this theme are naturally possible.

Through using a frame 7 of metal profiles in a floor structure element in accordance with the invention it is possible to manufacture the floor structure elements with great dimensional accuracy. Through furthermore casting the floor 4 in a special way it is also possible to obtain a, relative to the frame, well-defined and extremely smooth upper side of the floor 4.

This is obtained through using a form table (not shown) made with extremely good precision for the moulding of the floor 4, on which the frame 7 with the joists 5 and 6 and the reinforcing construction 13 are placed upside down and held flat, where- after concrete is poored to the desired level which is normally determined by the height of the side profiles 8 and 9. In the case when there is a depression 14, naturally a local filling of concrete to a higher level over a bulge in the form table is performed. The frame is hereby complemented with extra profile elements for this part of the floor.

It has been stated above that the floor is cast in concrete but also other materials and embodiments can possibly also come into question for the prefabricated floor struc- ture elements of the type in question here. The intention is that the floor structure element shall be able to be connected to the frame of the house and mutually in such a way that they also function as stiff, horizontal force-transmitting surfaces to a central stiff unit in the building. The required dimensions should naturally be adapted to the actual need.

The joists have above been shown to be completely under the floor 4 with their upper flanges supporting against the underside of the floor. According to an alter- native embodiment the upper flanges of the joists can instead be cast into the floor.

With such an embodiment the joists will be higher up in the floor structure element, and it will therefore become possible to fasten the reinforcing construction directly onto the joists and in this way replace the coupling means 12.