Supports – Pipe or cable
Patent
1979-12-10
1984-04-17
Foss, J. Franklin
Supports
Pipe or cable
52167, 248634, F16L 300
Patent
active
044429894
DESCRIPTION:
BRIEF SUMMARY
This invention refers to a cable bearer system, earthquakeproof, for atomic power stations and similar, consisting of, in particular, I-shaped bearers arranged vertically at intervals one behind the other in the direction of the cable and several brackets fixed to the bearer which stand out horizontally at the sides. The bearer has holding plates at one or both ends which can be fastened to the building construction.
In earlier systems of this type the bearers were fastened on either side to the building construction by inserting wall-plugs of considerable length, e.g. 200 mm, at appropriate intervals in groups in the concrete ceiling and/or floors, and the holding plates were fastened there by threaded bolts.
It is also usual to hang the bearers or to use short stands. The bearers are also fastened to other bearing constructions, e.g. steel bearers.
However these constructions are unsuitable for use in earthquake-proof nuclear power station constructions. The forces produced by the earthquake demand particularly strong and long safety plugs as the very strong attacking forces, in particular tensile forces, cannot be absorbed in any other way. The space between the plugs of a holding plate should be approximately 190 mm in accordance with existing regulations under application of M 12, whereby the space between neighbouring bearer plates with four wall plugs amounts to 19 mm, according to the opinion of the TH Darmstadt.
Furthermore the holding plates must be extremely large and strong.
The demands on the quality of the materials used are also extremely high.
All these demands are justified because, if the bearing system is subjected to earth tremors or quakes, the wall plugs are exposed to extremely high tensile forces. This has led to the situation in which suggestions have been made to cast large steel plates in the concrete ceiling and to fasten the bearing plates to these.
The amount of planning required for this would be awfully high, because the exact position of the bearers of the system would have to be determined at the very beginning of construction and, furthermore, an extremely exact placing of the steel plates would be necessary, so that the bearers could later be fastened in exactly the predetermined position. The variability of the system would thus be so limited that later alterations or additions would be practically impossible.
Note must also be taken of the fact that fitting wallplugs of the above mentioned length necessitates a complicated procedure to locate the iron in the concrete.
The same amount of effort as for the cable bearer systems in nuclear power station construction is also required for the installation of ventilation and pipe lines.
The varying load conditions must be calculated for each fixture point and taken into account when installing the system.
Grid- or ladder-shaped shelves are fitted to the cable brackets before the individual cables are laid. This ensures an even distribution of the cable weight, carries off the operating heat of the cables and facilitates cable changing.
The above development would lead to unmanageable dimensions and an intolerable work load for designers and engineers.
Thus the problem was to create a cable bearing system of the type described at the beginning which is earthquake-proof, with less planning and engineering effort. The system should also consist of as small a number as possible of simple components.
In general, the invention suggests the following solution to this problem: to join the existing cable bearer system of brackets to a stiff unit and to fasten this unit via a sprung, oscillating absorbant system to the building construction.
In detail, the invention is to be seen in the fact that, in each case, at least two neighbouring bearers are braced together to form a stiff elementary unit of the bearing construction and that the holding plates are fastened to the building construction with intermediate spring elements, effective in all directions, and absorber elements, effective in one direction.
Contrary to the present techniq
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