Generally known about joining of reinforcement using today technology When manufacturing cast building elements with slabs, strengthened with cast-in truss beams, it is common to use zig-zag truss webs consisting of steel rods attached to a chord.

If the chord consists solely of a steel pole, a very good quality of the performance of the welding demands an especially educated and skilful"licensed welder"to do the work. Also, there is always a risk for brittle breakage when assembling building elements in cold weather, or when subjected later to a load in cold. Furthermore, a welded strength joint construction always warps owing to thermal interior tensions.

To deal with these issues, we have successfully embedded a longitudinal load-supporting reinforcement rod inside a concrete chord. We have joined truss diagonal web members of steel into a web unit, or assembly, between the chord and a slab. The chord concrete then also embeds the web members where they connect with the chord reinforcement rod.

Tests at The Royal Institute of Technology in Stockholm show that each web member, without the need for welds, must be provided with perpendicular or oblique bends toward the direction of force to get necessary fixation between the load supporting reinforcement rods. Then the concrete chords and the web members are fixed together without the need for welding.

The tests show that such building elements function very well, both when subjected to load with a tensioned chord or with a compressed chord, and also at great spans.

Bending automates Today there are bending machines, called automates, which use reinforcement rods from huge coils, from which the rod passes through a straightening machine before it is bent and then is cut off after the bending process. This manufacturing is very fast and such machines have a tremendous capacity, and exist all over the world.

Accordingly, there is a great economic advantage to be able to use these. But, only webs designed very specially, i. e., in a simple triangular shape, will do for our purposes.

The beam web units consist of. small parts, web members, which must be joined together into a coherent truss, or a skeleton, with load supporting reinforcement rods, and then embedded in the chord and the slab.

The number of the web members can be several thousands in a common small house. However, with this invention it is a simple process, taking relatively little time, to get these web parts in position in the truss.

Hanging chord moulds Our web designs in earlier inventions make feasible the use of divisible hanging chord moulds when casting the chord and a slab, in the same working moment, into a building element.

To overcome a positioning problem, the chord moulds are equipped with recesses in the dividing plane, to make room for the web members. In industrial manufacturing of building elements, the web members must be in an exact and distinct position to fit in the mould recesses, each time these are used. This invention also provides the solution for this.

Purpose and important characteristics of the invention To place the web members in exactly the correct place in the truss, it is necessary to use a jig with a special design that guides both the web members and the longitudinal reinforcement rods.

The jig will simultaneously keep all reinforcement rods in exact position when fixing the longitudinal rods and the web members together into a truss.

Furthermore, the invention contains a hang-up arrangement for temporary frequent uses when spreading out the web members.

The jig : The jig consists of a base beam which has been equipped with specially designed sheet metal holders, which holders have been set out on strict distances from each other along the base beam.

Furthermore, between the sheet metal holders there are seated prisms or pyramids with mainly rectangular base, and with these bases lying on the base beam.

Sheet metal holders: The task of the sheet metal holders is to hold up the longitudinal chord reinforcement rods at a fixed distance from the base beam to: 1) guide the pyramidal reinforcement rods situated inside the web members base, called triangle base rods, into a correct place seen in the beam's longitudinal direction, and 2) keep each triangular web member in a correct position laterally and alongside the bases of the web members.

The bases of the web members shall land next to the sheet metal holder's lower edge and rest on the base beam, near the pyramid.

The sheet metal holders limit the longitudinal space at one direction for the bases of the web members, and will guide the chord rod sideways to a recess in the upper part of the sheet metal holder. To achieve this the chord rod is moved toward the centre of the sheet metal holder, which also moves the triangle base rods toward the flanks of the holders. The holders, seen from the beam end, have a silhouette similar to two peaks. The tops of the peaks lie approximately in the third part of the width of the sheet metal holder. The recess for the cord reinforcement rod lies between the said peaks.

The triangle base reinforcement shall not be locked vertically by the sheet metal holder. Therefore the sheets have strait vertical flanks. The triangle base rods weigh upon the web members in order to fix them more securely in the plane of the base.

The width of the sheet metal holder has been adjusted to get the triangular base reinforcement rods inside the bent curvature of each web member.

The Pyramids: For simplicity, the pyramids or the prisms are called"the pyramids"in the future.

As the web members are lowered onto the jig, the pyramids guide the lower part of the web member, the base, to the correct place longitudinally and then fix it in the correct position.

This is achieved by placing the base of the pyramid at a certain distance from the sheet metal holder to get space for the base of each web member, respectively.

The pyramids limit the space of the base of the web member longitudinally at the other direction. Please compare with the paragraph above.

The pyramid must be high enough for its sides to get steep enough to overcome the friction, which may otherwise impede the web member to slip alongside the pyramid.

This arrangement allows the web members to be roughly spaced along the jig, where each member needs to be placed just inside the space that is restricted by each sheet metal holder and its respective pyramid top.

Hanging arrangement: Now a hanging arrangement is needed to facilitate the spreading of web members before the reinforcement rod and web package is lowered onto the jig.

The hanging arrangements will consist of a certain number of mounting hooks with a well-defined position above the jig, when seen in the longitudinal direction of the beam.

Practical use of the jig : A truss of 8 m contains from 40 to 50 web members. A certain number of web members for the complete beam are put in a row and squeezed together.

The chord reinforcement rods are threaded inside the top- loops/top-parts and the triangle base rods are threaded inside the triangle part.

Then the web members are bundled, in correct number, between the mounting hooks."The truss-embryo"is hunged by the mounting hooks and the web members, before they are lowered, are distributed to the approximately correct centre/centre- measure above each respective partition.

The triangle base rods are kept somewhat apart, laterally, in order to land at each side of the tops of the pyramids and the sheet metal holders. The truss-embryo is afterward lowered on place while subjected to some shaking. Now all reinforcement rods and all web members lie perfectly.

In the work of an instant! ! Bonus : Because the base of each triangle web member slides down along each respective pyramid flank, the rod lands on the base beam quite close to the base of the pyramid, but at a little distance from the sheet metal holder.

If you want to fix the web members to the reinforce rods by tack welding, this"little distance"is needed when loosening the ready truss, because steel always shrinks after cooling from welding.

If one chooses welding as a method of joining the contact points of the truss, they must be joined according to a welding plan that will prevent the truss from being crooked or shrinking due to welding heat tensions. The"little distance,, allows the truss to shrink a bit, thereby facilitating the lifting of the truss from the jig after being joined, without hanging up on the adjacent sheet metal holder.

What happens at the upper part of the web unit? When a truss-embryo is lowered, each web member base lands at the base beam after first having slipped down along the side of the pyramid. As they slip down the pyramid, every web member automatically inclines towards right direction, and

therefore the tops of the web members land precisely at the chord reinforcement rod.

The web members position sideways : Each web member keeps in correct position in its upper part with help from the chord rod and, in its lower part, by help of the two triangle base rods. These rods have been forced apart by the sheet metal holder's increasing width from that part from the top to the straight parallel flanks, going downward.

Each triangle base rod always lies in the bottom of the web members, bent corners and fills up the space between the outer parts of the triangle base rod and its respective sheet metal holder. It is impossible for the web members to move from this correct position.

The result: Each web member now rests with millimetre precision (extreme precision) on the cord reinforcement rod in the upper part and is joined to the rod by tying or tack welding.

The precision is sufficient for the web members of the ready truss to fit to the above mentioned recesses of the hanging mould.

With a simple hoist (i. e. a small telpher) a man can easily manage to heave the other end of the truss.

In reality it takes considerably longer time to read this than to get the web members in place.

Building elements manufactured with this arrangement have, in practice, shown such close tolerances, along the upper side of the chords, that fibre boards can rest firmly on them without need of screws. Merely a thin elastic strip is put between the cords and the board to avoid clatter.

This saves much time during the floor mounting. Furthermore, the structural floors serve as installation space for water pipes, ventilation ducts, electric and sewage installations.

All installations can be made without making holes in beams.

The invention is defined by the enclosed, self-dependent patent claim. Performance of the invention is defined in the dependent patent claims.

The invention will, in the following, be described by using an example, with references to the enclosed drawings.

Brief description of the drawings Fig 1 shows, in perspective, the end of a jig according to the invention.

Fig 2 shows web truss parts ready for joining, located in the jig end, according to fig 1, The jig is indicated by dotted lines.

Fig 3 shows, in perspective, the end of a jig according to the invention with guiding devices shaped as prisms, symmetrically placed around their respective sheet metal holders, according to the invention.

Fig 4 shows web truss parts ready for joining, located in the jig end, according to fig 3. The jig is indicated by dotted lines.

Fig 5 shows a"web truss-embryo"where the web members have been arranged in bundles with load supporting reinforcement rods threaded into them.

The truss is now ready to be hanged in temporary hanging devices above the jig in order to facilitate the web members to be approximately equally divided along the jig.

Fig 6 shows a complete web truss, where the reinforcement rods 13,14 and the web members 15 have been fixed to the jig and have been joined to each other, ready to be cast in a chord and a slab, or in a second chord.

Fig 7 shows a part of a complete building element in cross- section. The section shows one single stiffening truss beam among others in a building element within a slab that is wider than shown.

A stiffening truss beam comprises in this example a chord and web truss cast together.

The section also can refer to a complete truss beam with just one truss beam and one cast chord with one wider chord underneath.

Fig 8 shows a part of a complete building element in a side view. The reinforcement rods are not shown.

Description of example of performance The following is a description of a jig, which has been adapted to a web member design according to PCT SE 94/00700 fig 20 and 21 and which web member has been named delta-et web. This web member is designed with a loop-shaped part, which is embedded in the chord.

Use of the loop facilitates the assembling operation further to get the web members on site as a chord rod is threaded inside the loop to prevent it form moving around inside the triangle area.

Ifs not in itself necessary that there is a base rod part on the web members to get this invention functioning, but the triangle legs can very well end up with end bendings which are embedded in the slab. But it is much easier to thread the triangle base rods into a big triangle than into end bendings. In any case the triangle base rods land up easily and automatically in their right places with this invention if there is a base part.

In a web furnished with a crossed upper part below a loop, hanging moulds, which tighten with a straight simple partition next to the cross, can be used. The recesses for the web members in the two mould parts land up"in the middle"of a straight partition which is the joining part of the mould. At the base of the loop the straight parts of the truss cross and touch each other. It's easy to make the mould fit around this junction to prevent the casting composition to leak out through the mould, which is a major goal.

The delta-et web members can, with advantage, be delivered in piles or threaded on a transport rod inside their loops, which transport rod can be removed and directly be replaced

with the reinforcement rod of the chord. This technique will speed up the process of this part of the manufacture, also.

Fig 1 shows, in perspective, the end of a jig according to the invention.

Fig 2 shows web truss parts ready for joining, located in the jig end, according to fig 1. The jig is indicated by dotted lines.

Fig 1 and Fig 2: The jig can, as an example among others, consist of a base beam 1 and a set of sheet metal holders 2 located at certain distances from each other along the base beam 1.

Between the sheet metal holders 2 are prisms or pyramids placed 3,9, 12 with principally rectangular bases towards the base beam.

The purpose of the sheet metal holders 2, is to hold up the upper cord reinforcement rod 13 in an exact distance from the base beam. And initially guide the reinforcement rods 14, 14' into the base of the web members called the triangle base rods 14, into correct position, seen from the side of the beam. And, subsequently, keep the web members 15 in correct position seen from the side and longitudinally along the beam.

The web base 17 of each member shall, for best function of the building elements, land next to the base 10 of each respective sheet metal holder and at the same time rest on the base beam 1.

The sheet metal holders 2 (in fig 1) have guiding devices 6 which lead the chord rod 13 (in fig 2) sideways to a recess 4 (fig 1) in the upper part of the sheet metal holder 2. The holders have two additional guiding devices 5 in the upper part which guide two rods 14 and 14', toward the two flanks 8 on the outside of the sheet metal holders 2.

In the top the sheet metal holder there are two peaks 7 situated in the third part of the width of the sheet metal holders, which peaks separates the two guiding devices 5 and 6.

The two triangle base rods 14, 14'then land inside the bent curvature 18, which will efficiently fix them in place. The triangle base rod 14'is shown as dash/dot lines.

The pyramids 3 guide the web members'lower parts, i. e. the base 17, into correct position, and keep them longitudinally correct.

This is achieved by locating the base of the pyramid at a proper distance from the sheet metal holder in order to provide space for the base of each web member.

An example of a pyramid is here shown consisting of two angularly bent rods 9-12-9 inclining towards each other and touching at the top 12, the rods thus forming the edges of the pyramid. The ends of the rods 9 form the bottom corners of a rectangular pyramid at the base beam 1.

The base 17 of the web member 15 slides downward along the side of the pyramids, formed by two flanking rods 3 in the corners of the pyramid.

The pyramid base limits the space 11 for the triangle base 17 in one direction, and the lower part 10 of the sheet metal holder limits the space in the second direction, longitudinally.

Furthermore, the triangle reinforcement rods 14 fix, together with the flanks 8 of the sheet metal holder 2, the web members 15 sideways in the lower part, and do the same service in the upper part of the recess 4 of the sheet metal holder. This arrangement is impossible to move except by violence.

The effect with this simple arrangement is that the web members 15 need only to be divided roughly along the jig, where each member 15 has been placed inside the space which is limited by the sheet metal holder 2 and the pyramid top 12.

When the truss-embryo is lowered onto the jig, everything falls in place by itself.

A prism with the same task as the pyramid can be formed by separating the bendings 12 and eventually connect the bendings to each other, e. g. with a rod.

You can of course use solid bodies to create the prism or the pyramid.

Curved flanks and other shapes are also conceivable both for the sheet metal holders and for the prisms/pyramids.

Fig 3 and Fig 4 Show essentially the same as fig 1 and fig 2, but here the sheet metal holders have been placed in the centre of a prism which has been formed of inclining rods 3 or inclining sheets 21. The lower parts of the rods 9 are attached to the base beam 1 at a suitable distance to give space 11 for two opposite base parts 17 of a web member 15.

The upper parts 12 of the inclined rods 3 and, respectively, the inclined metal sheets 21 are attached to the sheet metal holders 2. This also gives steadiness to the holders.

Fig 3 also shows a distance device consisting of a metal sheet 22 placed in the centre of the sheet metal holders 2 which sheet guides base part 17 of the web member 15 longitudinally, with better result.

Fig 5 shows a"web truss-embryo"where the web members have been arranged in bundles with load supporting reinforcement rods threaded into them.

The truss web members in the example are designed with a loop in the upper part.

The truss is now ready to be hanged in temporary hanging devices above the jig in order to facilitate the web members to be approximately equally divided along the jig.

Fig 6 shows a complete web truss, where the reinforcement rods 13,14 and the web members 15 have been fixed to the jig and have been joined to each other, ready to be cast in a chord and a slab, or in a second chord.

The truss web members 15 are in reality much closer next to each other, but have been shown a bit away from each other for drawing technical reasons.

The web members 15 in the example are designed with a loop 16 in the upper part.

Fig 7 shows a part of a complete building element in cross- section. The section shows one single stiffening truss beam 19,13, 14,15 among others in a building element within a slab

20 that is wider than shown. A stiffening truss beam comprises in this example a chord 19 and web truss 13,14, 15 cast together. The section also can refer to a complete truss beam with just one truss beam and one cast chord 19 with one wider chord underneath 20.

Fig 8 shows a part of a complete building element in a side view. The reinforcement rods 13,14 are not shown.

Even if in essential parts only a few of the design options of the present invention have been shown on drawings and described above, it should be understood that the invention is not restricted to these designs but are limited only to those indicated in the patent claims.