We design the membrane structure with these rules and regulations
Every project starts with computer aided structural analysis.
Then we choose structural material and products. Materials currently used in fabric structures consist of a woven textile encapsulated in a polymeric coating. There are different constructions of weave, weaving techniques and coatings that all lead to variations in the characteristics of the materials. These variations need to be understood and considered in the design process.
From an engineering point of view fabric structures are thin membranes which by virtue of their surface shape and inherent large deflection behaviour are able to support imposed loads. They are modestly prestressed to enhance their stiffness.
We continue production with rules of structural design and execution
The fabric patterns are computer generated for maximum accuracy and balanced loads per standards
Accurate fabrication dimensions are essential to the successful construction of fabric structures. This requires membrane cutting patterns to be taken out of the “at prestress” model of the structure. Seam lines between panels of cloth are defined by geodesic lines for efficiency in material use. Patterns have to be “compensated”, that is shrunk by percentage values in both warp and weft directions so as to allow for the development of strains necessary to give prestress. Batch testing of the fabric to be used in the work has to be carried out to determine these values.
In addition to the fabric related items, schedules will also be required for accurately dimensioning cables, taking into account stretch compensations and adjustment details. The shop drawings for metalwork items including membrane plates and support masts and frames have to be developed, and these should take into account final form geometry and angles.
The individual membrane elements are to be packed in accordance with the packaging instructions (folding plan, marking specifications, type of packaging, planned transportation) in such a way that any damage in transit is excluded and that identification of discrete items at the site is possible.
In order to prevent any damage by chafing during transportation, each individual membrane element has to be wrapped in a protective covering.
The packaging has to be chosen so as to ensure damage-free loading and unloading. When packing PTFE coated glass fibre material, every precaution has to be taken with respect to its susceptibility to fold damage. Appropriate packaging materials are various foamed materials, jacketed PVC tubes, “bubble wrap”. Crosswise folds should be avoided. The folded and packaged membrane must not be walked on or put under load at
any stage by depositing other components on it. For truck or container transport separate precautions may have to be taken, such as the use of intermediate floors.
During the erection phase, stresses initially tend to flow mainly through the membrane rather than through the edge ropes which remain slack until the membrane reaches its tensioned position. Thus, the weight of the fabric is carried solely by its connection to the corner.
Corners themselves have a particular mass that shall be taken into account during the installation procedure. Temporary support may be needed to hold the corner in place and properly direct it to its rough final angle.
Installation devices are needed to enable the lifting, stretching and pre-stressing of the membrane. The corners shall be provided with means of attachment such as spare holes, for instance.