Cables in Membrane Structures

 

Membrane Structures are often reinforced by cables. They can be used to stabilize the boundaries of the membrane panel when insetred into cable pockets. They can be used for creating the ridge or valley lines of those Membrane Sturctures. Cables are reinforcing supporting masts of Membrane Structures or create the primary construction on which the membrane is attached to.

 

 

Key Facts

According to DIN Standard 18 800 cables are rated as high tensile tension members.

Cable consist of many individual wires, i.e. individual cross sections. This reduces the defect rate per cross section as compared to monofilament individual cross sections (e.g. solid rods) to a minimum or even zero.

In lightweight constructions the following types are used: Spiral Strands (left picture) or Full Locked Cables (right picture).

Copyright by Pfeifer Seil- und Hebetechnik

  • Poured anchorings, acc. to DIN EN 13411-4 (see picture below)
  • Ferrules acc. to DIN EN 13411-3
  • Steel ferrules


All cable end connection calculations are based on the characteristic breaking load of the cable system.

Free cable length between fittings shall be at least fifty times the cable diameter for type 1 x 19 and 1 x 37. For all other types free cable length shall be at least seventy times the cable diameter

Copyright by Pfeifer Seil- und Hebetechnik GmbH

Unloaded cables show a non-linear load/elongation behaviour. Even cables of the same design and diameter have to be exposed to a defined load before their lengths can be compared. Elongation can be predicted for a prestretched cable only. Therefore the cables are prestretched and respective length measured under preload.
Required geometry and preloads are already taken into account during manufacturing of cables in the plant.

Corrosion protection is an essential component of safety engineering. Materials and substances used in corrosion protection must be environmentally safe and must offer a long-term effect. Corrosion Protection of cables can essentially be subdivided into four areas:

 

  • Corrosion protection via constructive measures on the structure
    Rainwater running down the cables must quickly run off in areas such as end anchorages and clamps. If required, appropriate drilling or grooves for the water to run off have to be applied so that no water remains trapped in these areas. All connection plates on the structure must be designed in such a way
    that appropriate ventilation of the cables is guaranteed and humidity can dry quickly. Furthermore, it is essential that cables and cable connections are not in areas where they are directly sprayed with road salt.

  • Corrosion protection of the individual wire
    Either galvanized wires with zinc coating according to DIN EN 10264-3 or galfan coated wires offers effective corrosion protection.

  • Corrosion protection of the cable’s interior (inner filling)
    Cavities in the cable’s interior between heavy galvanized round wires and profile wires are filled with an active inner filling: PU-oil-based zinc dust paint, or alternatively low-solvent, highly pigmented single-component zinc paste. The outer GALFAN coated profile-wire layer, or in the case of thicker cables
    two GALFAN coated layers, does not receive an inner filling. Escape of the inner filling to the cables surface if therefore reduced to a minimum.

  • Corrosion protection of the cable surface including end connections

In most cases appropriate constructive measures render fire protection systems on the cable and its components unnecessary, as cables don’t add fire load. They are usually located far away from possible fire. In uncertain cases the fire authority report and building regulations of the federal states will specify the required fire protection system.

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