Tensile membrane structures use a unique technology which gives architects,
designers, and engineers to create
exciting structures as well experiment with the shape. These types of structures are visually quite
exciting and they are economically competitive and environmentally good as
well.
The materials used in these types
of structure are quite lightweight and
they are quite efficient in the long run.
In addition, they provide the cover of the building as well as come up with a
basic architectural form.
In general, it is seen that the
conventional structures depend on the stiffness in order to carry loads and to
attain stability.
On the other hand, the fabric structures
are constructed using elements that have shear stiffness and they use the
internal tensile forces in order to carry the loads. These kinds of structures
can be quite complicated to design as they possess highly non-linear behavior.
In addition, when the design starts, then the shape is also not known.
Once the tensioned fabric starts
to deform, then it potentially increases the capacity to carry the load. The
applied load to self –weight ratio is very well maintained as compared to
concrete and steel structure of the same load.
Why is the tensile
shaped like this?
It is known that flat and large
pieces of fabric are quite poor in terms of resisting the loads. For instance, take
a ball and attach it to four strings. Try to lift
the two opposite strings up and on the other hand lowering the other two
strings.
You will notice that the ball is locked in the
space. You can apply the same principle to fabric membrane and you will come
across anticlastic double curvature surface. It may sound quite impressive but
the fact is that it is emerging from the three pre-defined fabric shapes such
as a cone, hyper, and the barrel.
What are the
limitations of the fabric membrane
structure?
The fabric membrane structure has
limited use as many don’t have the knowledge in terms of its strength,
behavior, design process and application. Also, there is no Indian standard
code available for the fabric structure design. Hence, the design typically
depends on past experience and research.
But, there can also be times when the experiential information may not be
correct.
What is the future
scope of the fabric
membrane structure?
A lot of technological
advancement is taking place in the fabric membrane although there are some
problems that still need to be addressed. It is certainly hoped in the future
that some methods would be developed in order to make the membranes last for a
long span of time. It is also known that if technology
increases, then the quality of the material would also increase.
Hence, to improve the innovative
work, safety, and design, it is very
important that a lot more techniques are being developed and thus a lot more
researches need to be carried out. Also,
the publication of the standard code should be done on the basis of the
country.
What are the materials
that are used for coating the Tensile Fabric membrane?
There are four commonly used
materials that are used for coating the tensile fabric membrane. It has been
mentioned below in brief:-
·
PTFE coated glass fabrics
PTFE is the acronym used for Poly tetra fluoro
ethylene. This coating material is quite common and it is widely used as it is
backed with a lot of outstanding and multipurpose properties. This has been
made possible because of the tetrafluoroethylene monomers chain arrangement.
It is also a very good thermal insulator as it can easily resist the high
thermal temperatures and it also has a very low coefficient of thermal
conductivity. It is also quite resistive against the abrasion and the corrosive
substances such as sulphuric acid and hydrochloric acid.
·
PVC coated polyester fabric
PVC is the acronym used for
Polyvinyl chloride and it is applied in the form of paste on the fabric. It
assists in cleaning and it helps in enhancing the surface aspects. Besides
this, it helps in improving the yarn thermal properties. For the purpose of
fire resistance, different substances are applied such as phosphates,
phthalates or ester as a secondary coat of plasticizes.
In addition, PVC is also used for
light stability and imparting the color.
The PVC coat is used with the stabilizing molecules in order to achieve
oxidation, thermal and UV protection.
·
Silicone coated glass fabrics
Silicone macromolecules are cross-linked in order to obtain the silicone
coating. The silicone chain is used on the yarn such as a protective coating is
provided. One of the great advantages of
silicon is that the chain of the molecules can be very well combined with
varied chemicals to obtain the coating having specific property as per the
requirement of the structure.
For instance, Silicone substrates
are combined with glass such as a covalent hydrophobic film coating is formed.
·
ETFE
foils
ETFE is the acronym used for
Ethylene Tetra Fluoro-Ethylene. It is a copolymer of tetra Fluoro-Ethylene and
ethylene and they have a very high melting point i.e. between 250°C to 270°C.
ETFE foils have transparency advantage as compared to the other materials. It
allows for the transmission of incident light up to 90%. In addition, it also
helps to distribute stress.
What is the design
process of the Tensile Fabric membrane?
The Design process of the Tensile
Fabric membrane is divided into three
types such as:-
1) Form-finding
Form-finding is known to be an iterative
process in which the designer finds the best possible shape that a membrane can
adopt.
2) Static and dynamic equilibrium
For structural designing, it is very important to look out for
different kinds of load combination. Further,
the analysis is done in order to find the deflection.
3) Patterning
It is known to be a process in
which the 3D membrane which is pre-stressed is transferred into a pattern of 2D
for the structural purpose.
Conclusions
Fabric membrane structure
has a lot of benefits associated with it such as durability, simple construction, heat controlling capability and sunlight controlling capability to name a few.
It is observed that the membrane shape is dependent on the initial force and
not on the property or type of the fabric.
