Tensile Solutions


Conical Tension Structure


Hyper or Anticlastic Structure


Parallel Arch or Barrel Vault Structure


Cable Net & Membrane Structure

Tensile Membrane

Our company Delta tents & Tensile Shades offer a wide range of Tensile Membrane. As we are Historically inspired by some of the first man-made shelters—such as the black tents first developed using camel leather by the nomads of the Sahara Desert, Saudi Arabia, and Iran, as well as the structures used by Native American tribes—tensile structures offer a range of positive benefits compared to other structural models.

Tensile structure is the term usually used to refer to the construction of roofs using a membrane held in place on steel cables. Their main characteristics are the way in which they work under stress tensile, their ease of pre-fabrication, their ability to cover large spans, and their malleability. This structural system calls for a small amount of material thanks to the use of thin canvases, which when stretched using steel cables, create surfaces capable of overcoming the forces imposed upon them. Structurally, the system is formalized by combining three elements: membranes, rigid structures such as pole and masts, and cables.

The membranes of PVC-coated polyester fibers have greater ease in factory production and installation; lower cost; and medium durability—around 10 years. PTFE-coated glass fiber membranes have superior durability-around 30 years; and greater resistance to the elements (sun, rain, and winds); however, they require skilled labor.

Some of the other features are as follows:

  • Longer life cycles of materials.
  • Materials can be re-used in form.
  • Most materials are completely recyclable.
  • Less impact on site.
  • Less construction debris after demolition.
  • Unique designs.
  • Lightweight and flexible.
  • Environmentally sensitive.
  • High strength weight ratio.
  • Little to no rigidity.
  • Loss of tension is dangerous for stability.
  • Thermal values limit use.
  • Load Transfer on Fabric Structures.
  • Attachment Weaknesses in Mono cover Fabric Structures.

Membrane Structures are highly popular in architectural design now a days. There is trend of using membrane structures. It satisfies both attractive architect’s design as well as structural design. Due to its light weight, earthquake force is neglected, whereas wind load is critical for the structure. Fabric resists tension and has no compression or bearing. Due to its light weight and stretch property, they can be used on places such as stadiums, large parking etc. Computer aids like Form Finder, Dlubal RFEM and AutoCAD is used for modeling and analysis.

Tensile membrane Structure:

Tensile membrane structures forms a part of a unique technology which gives designers, architects and engineers the ability to experiment with form (Shape) and create exciting structures. These structures do not only visually exciting, but are environmentally good and economically competitive as well. Since the materials are lightweight, they are very efficient in long span applications and are frequently constructed with considerable savings in the foundation and supporting structure costs. As an additional benefit, they do additional than just transmit forces to the ground. They provide the basic architectural form and provide much of the building cover. Conventional structures depend on internal rigidity (stiffness) to attain stability and to carry loads. Fabric structures constructed of elements that have small or no bending or shear stiffness (cables and membranes) must depend on their form and internal tensile forces to carry loads. These structures are complicated to design as they have a tendency to be highly non-linear behavior; also their shape is not known when design starts. Tensioned fabric increases its capacity to carry load as it deform. They can maintain high ratio of applied load to self –weight, as compared to steel and concrete structure for same span.

Fabric Details of tensile fabrics

PVC coated polyester fabric
PVC stands for Polyvinyl Chloride and is applied on the fabric as a paste. It improves the thermal properties of the yarn, provide enhanced surface aspects and helps in cleaning. For fire resistance a secondary coat of plasticizes are applied such as phtalates, phosphates or esters. PVC can be used for imparting color and light stability. The PVC coat is implanted with stabilizing molecules to achieve thermal, oxidation and UV protection.

PTFE coated glass
Fabrics PTFE stands for Poly tetra fluoro ethylene. It is the most common and widely used coating material as very few coating materials can provide such a multipurpose and outstanding properties. All this is possible due to chain arrangement of the tetrafluoroethylene monomers. It is one of the best thermal insulators as it can resist high thermal temperatures and has a comparatively low thermal conductivity coefficient. It is highly resistive against abrasion and corrosive substances such as hydrochloric acid or sulphuric acid.

Silicone coated glass fabrics
Silicone coating is obtain by cross linking of silicone macromolecules. The chain of silicone is applied on the yarn to provide the protective coating. The advantage of using silicone is that the chain of molecules can be combined with different chemicals to gain the coating with the specific property as required by the structure. For example silicone based substrate are combined with glass to form a covalent hydrophobic film coating.

ETFE foils
ETFE stands for Ethylene Tetra Fluoro-Ethylene. It is a copolymer of ethylene and tetra Fluoro-Ethylene which has very high melting point ranging in between 250°C to 270°C. The foils have a transparency advantage as opposed to other materials. It allows transmitting about 90% of the incident light. Other advantage is to distribute the stress. ETFE foils International Research Journal of Engineering and Technology (IRJET) have a bilinear elastic isotropic distribution behavior of stress.

DESIGN PROCESS OF TENSILE

The methodology includes the way work is carried out. First, the process of design is explained, which comes in three main steps. As follows:

2.1 Form-Finding Form finding can be defined in the following ways: “Form finding is the iterative process through which a designer arrives at the best possible shape that the membrane can adopt under the applied initial force or pre-stress”. The process of form finding basically depends on the boundary conditions and initial force which decide the shape of the structure.

2.2 Static and Dynamic equilibrium for designing structures it essential to consider different load combinations taking into account the magnitude and direction. The curvature which may obtain by form finding is taken and analysis is done to check the permissible deflections. The dynamic analysis evaluates the relation between the fluctuating load applied and the structural geometry. As wind is the critical factor, the main objective is to perform dynamic analysis is to check the stability of membrane under wind load cases.

2.3 Patterning it is the process by which the pre-stressed 3D membrane (the form found structure) is transferred into a 2D pattern for the structure. At this stage the generated shape has prestress applied and the cutting pattern therefore has to be smaller than the final shape, as illustrated below.

STRUCTURAL MODELLING AND ANALYSIS

In this work, software used are AutoCAD, Dlubal RFEM5, Form Finder and Mpanel. To study the concept of geometry of fabric (form Finding), Initial load distribution and Deformation of the fabric membrane, simple analysis of membrane structure Hyper and Cone is performed in Dlubal RFEM5, with two different type of fabric membranes with different properties (named as PTFE Type A & Type B). In both models Initial Force of 1 KN/m & 2 KN/m is applied to observe the variation in Form as well as strains. Again the boundary conditions of membrane as Fixed and Free are considered to observe variation in results. MODEL -1: A Hyper of dimension 10 m x 10 m x 3 m is considered, in which Initial Force of 1 KN/m & 2 KN/m is applied and analyzed. MODEL -2:

A Rectangular Cone of 10 m x 10 m x 3 m is considered, in which boundary conditions as Fixed & Free is considered and analyzed.