Static structures (e.g. – buildings) – With component having discrete prestressing means – Slab or panel construction
Reexamination Certificate
2000-01-03
2001-10-30
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
With component having discrete prestressing means
Slab or panel construction
C052S378000, C052S379000, C052S583100, C052S259000, C052S742140, C403S291000, C403S269000
Reexamination Certificate
active
06308478
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device for connecting reinforced concrete sections. The device uses wire ropes which are embedded partially in a concrete section which was made first, and the ends which are not embedded protrude into a formwork of a second, adjoining concrete section.
It is known to connect concrete sections by embedding in one concrete section at the abutting surface wire rope loops or the like which then cooperate with corresponding wire rope loops of a second concrete section.
If the second concrete section is of cast in place concrete, it is also possible to concrete the wire rope loops into the second concrete section.
In order to simplify manipulation with the wire rope loops, it is known to provide at the edge of the formwork of a concrete section box-like inserts which receive the wire rope loops. After removal of the formwork, the boxes can be opened, and the wire rope loops which were initially turned in then adopt a position for connection to the adjacent second concrete section.
Wire rope loops of the type mentioned hereinabove can be employed both with cast in place concrete sections and also with pre-cast concrete sections.
It is known furthermore to bend in reinforcements of concrete sections in the edge region such that they are inside the formwork. In this case a box-like insert, for example, can be provided which receives the bent-in reinforcing bars. After removal of the formwork and optionally opening of the boxes, the reinforcing bars are bent out such that a connection to adjacent concrete sections is possible.
It is frequently necessary to use in the concrete section reinforcing bars of sizeable diameter. Increasingly, there is then a risk that the reinforcing bars may crack while being bent back. It also becomes difficult or impossible to bend in the reinforcing bars, as mentioned hereinabove, in the edge region such that the ends are initially within the formwork and are bent up only after removal of the formwork. In the case of reinforcements of sizeable diameter, there are therefore provided for example in the formwork openings through which the reinforcing bars project. It is also known to provide the ends of the reinforcing bars with pressed-on sleeves having an internal thread, such that correspondingly constructed reinforcing bars of the adjacent concrete section can be screwed into these sleeves.
However, the connecting of reinforcing bars of sizeable diameter which are bendable only with difficulty or not at all is altogether very labour-intensive. This is true both when introducing the reinforcement into the formwork and also when removing the formwork and when connecting adjacent concrete sections.
SUMMARY OF THE INVENTION
The object of the invention is to provide a device which enables concrete sections having reinforcements of sizeable diameter to be connected and with which the labour input for connecting the concrete sections is substantially less than with conventional methods.
To achieve this object the invention proceeds from a device of the type indicated at the outset, According to the invention it is proposed that the first concrete section has a reinforcement which terminates in the adjoining region of the second concrete section, that there are arranged parallel to the reinforcement in the first concrete section wire rope pieces for the free ends whereof there are provided receiving spaces in the first concrete section or discontinuities in the formwork of the first concrete section. The wire rope pieces can also, in place of the parallel arrangement, be arranged as an extension of the reinforcement if a suitable transmission of forces into the wire rope is ensured. A reinforcing bar, for example, serves as the reinforcement.
The invention is based on the thinking that a wire rope can be placed under substantially greater tension than a reinforcing bar of the conventional grade of steel. The cross section of the wire rope piece which takes up the tensile forces from the reinforcing bar and transmits them in analogous manner is therefore substantially less than the cross section of the reinforcing bar. This in turn means that the wire rope piece remains sufficiently flexible, such that the accommodation of the free end of the wire rope piece, for example in receiving spaces in the formwork of the first concrete section, is not problematic.
The essential advantages of the device according to the invention are, however, also obtained when there are provided in the formwork of the first concrete section not receiving spaces for the wire rope pieces but discontinuities for the free ends of the wire rope pieces. The drillings in the formwork which are necessary for the wire rope pieces are substantially smaller than equivalent drillings for the reinforcing bars. As the free ends remain movable, they barely inconvenience work in the region of this formwork. The ease of bending is also a substantial advantage during the transportation of pre-cast sections.
In the same manner as in the formwork of the first concrete section the tree ends of the wire rope pieces in the second concrete section can be connected to the reinforcing bars which are to be arranged there. The wire rope pieces then likewise lie for example parallel to the reinforcing bars there. Force transmission then also takes place in the second concrete section because the concrete is connected in fixed manner (adhesion effect) to the wire rope pieces as a result of the surface irregularities thereof, and an anchorage is obtained like that which results from the ribbed texture on the surface of conventional reinforcing bars. It is clear that the anchoring length of the wire rope pieces should be determined appropriately so as to prevent tearing out. While possible, the introduction of additional connections between the wire rope pieces on the one hand and the ends of the reinforcing bars on the other is not necessary.
It is generally sufficient if there is arranged parallel to the reinforcing bar a single wire rope piece for each reinforcing bar. In particular cases, and in particular in the case of very large reinforcing bar diameters, it may however be advisable to arrange a plurality of wire rope pieces parallel to a single reinforcing bar. It is clear that the deformability of the wire rope pieces, being then thinner, is improved as a consequence.
In a further embodiment of the invention there are provided in the first concrete section receiving pockets for the free ends of the wire rope pieces. The free ends of the wire rope pieces can for example be pushed into these pockets. After removal of the formwork the free ends are pulled out of these pockets in order to bring them into the position required for connection to the reinforcing bars of the second concrete section.
According to a further proposal of the invention, the free ends of the wire rope pieces can be rolled up or coiled up, thus improving the ease of handling of the wire rope pieces.
The receiving spaces are formed for example by box-like inserts in the formwork of the first concrete section. In order to prevent ingress of the liquid concrete these box-like inserts are capped. On removal of the formwork, the caps are taken off, and the free wire rope ends are then accessible,
The receiving spaces can also be formed by readily removable sheaths on the free ends of the wire rope pieces. For example, the free ends can be capped with a polystyrene sheath from which they can be readily pulled out or bent out after setting of the concrete and removal of the formwork. The remaining receiving openings are filled without particular measures when the second concrete section is prepared.
It is generally sufficient in the invention, as already explained above, if the wire rope pieces are installed to a sufficient length parallel to the reinforcing bars. In particular cases it may be appropriate to arrange anchoring elements at the ends of the wire rope pieces in the first concrete section. Such anchoring elements can, for example, be formed by pressed-on slee
Avak Ralf
Kintscher Matthias Richard
Friedman Carl D.
Jacobson & Holman PLLC
Pfeifer Holding GmbH & Co. KG
Thissell Jennifer I.
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