DESCRIPTION:

Technical field of the invention

The invention relates to a supporting beam of concrete provided with a reinforcement present in the concrete, which reinforcement comprises a number of parallel rods extending in the longitudinal direction of the supporting beam, as well as a first elongated reinforcing element that is wound helically around these rods and is attached to these rods, which reinforcement element comprises a continuous strand of flexible fiber material and a binder interconnecting the fibers of the material. Background of the invention

A supporting beam according to the preamble of claim 1 is known from DE102005030409A. Summary of the invention

An object of the invention is to optimize the construction of a supporting beam of a type as described in the preamble of claim 1. For this purpose the supporting beam according to the invention is characterized in that the reinforcement comprises a second elongated reinforcing element which also comprises a continuous strand of flexible fiber material and a binder that interconnects the fibers of the material and which is wound helically around the rods but in the opposite direction to that of the first reinforcing element, which second reinforcing element is also attached to the rods and furthermore to the first reinforcing element on the locations where the two reinforcement elements intersect, and that the concrete is high-strength concrete and the fiber material consists mainly of basalt fibers. By a continuous strand here is meant a strand that has a length such that the strand is wrapped around the rods at least once. The reinforcement forms a framework that gives extra strength to the supporting beam in both horizontal and vertical direction and that less compression-resistant material is needed to obtain a sufficiently strong supporting beam. Strands made from basalt fibers have been found to be extremely suitable for the application described above in that they are relatively light, strong and inexpensive. The use of high-strength concrete is necessary to obtain the desired strength of a supporting beam provided with such reinforcement. The combination of a basalt fiber strand wrapped around reinforcing rods and high-strength concrete results in a supporting beam that is lighter and stronger than the known supporting beam.

An embodiment of the supporting beam according to the invention is characterized in that the binder is formed by ceramic glue. By using ceramic glue instead of the usual epoxy, the supporting beam according to the invention can meet high fire safety requirements.

A further embodiment of the supporting beam according to the invention is characterized in that the basalt fibers are surrounded by a wire which is wound helically around the basalt fibers to hold them together. This further increases the strength of the strand and therefore also the strength of the supporting beam.

Yet a further embodiment of the supporting beam according to the invention is characterized in that the supporting beam comprises a lower part which is subject to tension in use and an upper part which is subject to compression during use, the cross section of the lower part being smaller than the cross section of the upper part. As a result, the supporting beam can be made lighter than a complete rectangular supporting beam, without appreciably detracting from the strength of the supporting beam.

The lower part of the supporting beam and the lower part of the reinforcement preferably have a shape tapering from the upper part of the supporting beam, for example roughly in the shape of a trapezoid. As a result, the truss construction not only provides extra strength in horizontal and vertical direction, but also in two directions at an angle to the horizontal and vertical direction (in the oblique planes of the trapezoidal shape), thereby providing extra strength to the supporting beam. More than one reinforcing rod is preferably present in the narrow bottom end. The upper part of the girder preferably has a rectangular or nearly rectangular cross- section.

Brief description of the drawings The invention will be explained in more detail below with reference to an exemplary embodiment of a supporting beam according to the invention shown in the drawings. Here is:

Figure 1 shows a schematic representation of an embodiment of the supporting beam according to the invention in cross-section;

Figure 2 shows the reinforcement of the supporting beam shown in figure 1 in side view; and

Figure 3 is a faithful representation of a reinforcement of a further embodiment of the supporting beam according to the invention.

Detailed description of the drawings

Figure 1 shows an embodiment of the supporting beam 1 according to the invention in cross-section and Figure 2 shows the reinforcement 3 of this supporting beam in side view. The reinforcement 3 is embedded in high-strength concrete 11, see figure 1, in which, during use, a lower part 1A of the supporting beam is loaded under tension and an upper part IB is loaded under pressure. The upper part IB has a rectangular cross-section and the lower part 1A tapers from the upper part and is roughly in the shape of a trapezoid. The surface of the cross-section of the lower part 1A is smaller than the surface of the cross-section of the upper part IB of the supporting beam 1, so that concrete and weight are saved, while this hardly or not adversely effect the strength of the supporting beam.

For clarification, this reinforcement 3, see figure 2, is an example of a simple reinforcement of the supporting beam according to the invention and consists of a number of parallel rods 5 extending in the longitudinal direction of the supporting beam and a number of strands 7, 9 of basalt fibers that are wound helically counterclockwise and clockwise around the rods and thereby crossing each other. In this embodiment, the reinforcement has only two strands. At the places 13 where the strands 7 and 9 are in contact with the rods 5, the strands are attached to the rods and at the places where the strands 7 and 9 intersect, the strands are attached to each other. Preferably more strands are wrapped around the rods, the strands also crossing each other at the top of the reinforcement and being attached to each other. The reinforcement with the rods 5 and the intersecting and joined strands 7 and 9 forms a truss, whereby extra strength is obtained. This makes the beams stronger / stiffer in the horizontal direction and there is less chance of bending in the horizontal plane. The strands can also be attached end to end to form one long strand. This strand is then wound back and forth between the ends of the rods alternately clockwise and counter clockwise around the rods with parts thereof crossing each other.

In the upper part IB of the beam there are four reinforcing rods 5B, one near each corner of the rectangular cross-section. Near the narrow underside of the lower part 1A of the supporting beam, there are three reinforcing rods 5A in order to be able to absorb great tensile forces. The reinforcing rods 5 can be of iron or another metal or of plastic. The strands 7 and 9 are made of basalt fibers that are joined together by a ceramic adhesive. The basalt fibers may be surrounded by a wire wound helically around the basalt fibers to hold them together.

Figure 3 is a faithful representation of a reinforcement 23 where the strands 27 have been manually wrapped around the rods 25. In this embodiment, the reinforcement 23 has more than two strands 27 wrapped helically around the rods 25. Because the strands are wound manually, they cross each other at random places. When winding the strands by machine, they will be present in a regular pattern. In this embodiment, the basalt strands are attached to each other and to the rods by means of a ceramic adhesive.

Although the present invention is elucidated above on the basis of the given drawings, it should be noted that this invention is not limited whatsoever to the embodiments shown in the drawings. The invention also extends to all embodiments deviating from the embodiments shown in the drawings within the scope of the invention defined by the appended claims.