Construction and bearing structure elements
Textile architecture making special demands on construction, material and design.
Membranes can only be subjected to tension but not to pressure. In order to obtain the desired and statically calculable stability it is mandatory to apply a mechanical pre-tension in connection with an anticlastic design. The more the membrane is deformed, the lower the pre-tension forces to be applied, such forces resulting ultimately from the outer load through wind and snow in the framework of the static calculation.
Unfortunately, it is often inevitable to accept compromises due to constraints imposed by building regulations. Supported by suitable form finding programs, Ceno engineers will always be pleased to assist you in finding the most efficient solution.
Bearing structures consisting of steel and steel ropes: The backbone of "Lightweight plane load-bearing structures"
It is advisable to plan membranes and bearing structures in an integrative manner. This is the only way to develop cost-effective and at the same time architectonically appealing, filigree buildings. Apart from its covering function, the membrane assumes static tasks relieving the bearing structure. This is obtained through the shaping and the enormous strength of high-tensile textile fabrics. Having a comparable specific tensile strength as steel, the approximate weight of the membrane amounts to just 1/5 of the weight of steel.
The advantages of the steel bearing structure are underlined by a multitude of variations using suitable connection details and by the possibility of pre-fabrication by the manufacturer. Cable structures provide additional aesthetic and economic aspects although this possibility may be limited by the floor space required for the bracing.
Apart from mechanically pre-stressed membrane surfaces, pneumatically pre-stressed - i.e. air-borne - cushion constructions, particularly made of ETFE foils have increasingly been used over the past years.
The way of static calculation also applies to the pneumatically supported structures where the load transfer from outer loads is carried out by the overpressure. Sufficient bending of the membrane surface is also required; the smaller the radius, the smaller the loads acting on the bearing structure.
The advantage of air-borne constructions is that they offer the possibility to use lighter bearing constructions which - apart from the outer loads - have to be designed for the horizontal loads from an air cushion only. Please note that the support air blower selected works with conditioned air and that it is equipped with a redundant circuit.
Due to the low basis weight of the cushions, the bearing structure's design can be very filigree and light. Using aluminium frames, the cushions are mounted over large roof and facade surfaces on the bearing constructions made of wood, steel or aluminium.
ETFE foil roofs are individually designed to meet the structural requirements of the building.
To achieve a thermal insulation effect, foil cushions with multi-chamber systems are used.
U values (1):
• 1.51 W/(m²K)
• 0.78 W/(m²K)
(1) Project-specific verification by a hygrothermal analysis for Düsseldorf/Duisburg