The unique flexible characteristics of the fabric membrane, tensioned membrane structures allow architects, designers, and engineers the opportunity to experiment with form and create visually exciting and iconic structures. The weight of the membrane in tensile structures is very less and consequently, the quantity of structural steel utilized to support the membrane is also minimal. Thus, the weight, as well as the overall cost of tensile structures is much less as compared to conventional roofing systems. As stainless steel is utilized, more useful space free of columns becomes available. As the weight of the structure is so little, it will not experience much acceleration forces under seismic action. There are different types and shapes of tensile membrane structures, each having their own specialty and application, which are explained below.
Different types of Tensile membrane Structures
There are three different main classifications in the field of tensile construction systems: membrane tensioned structures, mesh tensioned, and pneumatic structures. The first relates to structures in which a membrane is held by cables, allowing the distribution of the tensile stresses through its form. The second case corresponds to structures in which a mesh of cables carries the intrinsic forces, transmitting them to separate elements, for example, sheets of glass or wood. In the third case, a protective membrane is supported through air pressure. The different types are explained below.
Linear tensile membrane structures
In these types of structures in which a membrane is held by cables, allowing the distribution of the tensile stresses through its own form. Linear tensile structures are the structure in which all the members are in linear tensile forces. These linear members are supported by the compression members, but the major loads are carried out by tensile members. Different types of linear tensile structures are-
- Suspension bridges
- Draped cables
- Cable-stayed beams or trusses
- Cable trusses
- Straight tensioned cables
Three-dimensional tensile membrane structures
Three-dimensional tensile structures are a compilation of elements that are primarily in tension, with the compression being transferred to a central mast and down into the ground manipulating the framework with geometric shapes, tensioning membranes with sweeping arches, and creating pitches to otherwise simple lines, facades can transform ordinary buildings into iconic structures with stunning designs. Different types of three-dimensional tensile structures are-
- Bicycle wheel;
- 3D cable trusses
- Tensegrity structures
Surface-stressed tensile membrane structures
Surface-stressed tensile structures are the same as other 2 tensile structures, but the surface members are tension bearing members. This fabric structure is usually used in building facades and dome tents, a protective membrane is supported by means of air pressure. Different types of surface-stressed tensile structures are-
- Prestressed membranes
- Pneumatically stressed membranes
- Gridshell
- Fabric structure
Different shapes of tensile membrane structures
Owners and developers across the globe have discovered the advantages of building with tensile fabric building structures as opposed to traditional building products. Whether you are looking for an entertainment venue such as an amphitheater, walkway coverage for travelers at transit stations, or a structure to make your athletic fields suitable for year-round competition, a tensile fabric building structure may be the ideal solution. There different shapes of tensile membrane structures, which are used as per application, each of them is explained below.
Conical Tension or canopy structure
The conical designs can feature either single or multiple masts. For both design options, membranes are tensioned between a ring at the pinnacle and the lower perimeter support columns. The cones are highly effective for covering large areas and loading heavy rain or snow. The masts can go to the ground or can utilize a ‘flying’ mast where cables are used in tension supporting the mast in the air to allow for an unobstructed space below. For both design options, PTFE or PVC membrane is tensioned between a ring at the pinnacle and the lower perimeter support columns. Cones are especially effective in areas that need to comply with high rain or snow load regulations.
Anticlastic or Synclastic Structure
Anticlastic structures are those in which the centres of curvature are located on opposing sides of the surface. This is commonly-described as a saddle shape. A hyperbolic paraboloid is an anticlastic surface. Synclastic structures are those in which the centres or curvature are on the same side of the surface. This is a dome-shape. This can be created with an architectural fabric by inflation – that is, air pressure within the dome maintains the form of the surface when it is tensioned, rather than the opposition of the curvatures.
Parallel Arch or Barrel Vault Structure
This type of structure is a curved structural form that carries loads around an opening, transferring them around the profile of the arch to abutments, jambs or piers on either side. Arch are structurally very stable in compression, as loads are relatively evenly balanced through their form. Depending on the spans, a barrel vault system can be a very cost-effective way to incorporate tensile membrane on a project due to the repetitive nature of the design and efficiencies of materials.
Cable net membrane Structure
Cables are a fundamental component of our lightweight structures. Combined with advanced lightweight ETFE, PTFE, and PVC membranes, membrane structures require minimal structural support, which allows us to create amazing structures previously unimagined. These are used for long-span tensile membrane roofing applications typically found in stadiums or large spaces, 3D cable net or cable grid structures are an efficient solution for lightweight tensile architecture.
Conclusion
Membrane structures can be designed, analysed and erected in any shape or form we require. It provides extra space for the designer to experiment with different shapes. The membrane fabric can even incorporate artificial lighting, which can add another aesthetic dimension to them.
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