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Membrane structure is a perfect combination of the architecture and
structure. It combines the fabrics of high-intensity and flexibility
together with a support system to form the stable bent surface of
certain firmness, it features the space-structured formation and withstands
great load from outside. Due to such advanced features as elegant
shaping, lightweight, fire-resistance, ready to fabricate, quick to
install, energy saving and easy maintenance, it has been widely used
in various fields all over the world. This kind of structural formation
is specifically suitable for the construction of large-sized stadium,
advertisement board, sketch and public recreation sites, exhibition
halls and shopping center.
Construction Form Class
of Membrane Structure:
In terms of structure forms, membrane structure can be classified
into 3 forms. They are Frame Supported, Tension, Air Supported Structure
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| The membrane structure at the entrance of Haikou
Sea World |
1. Frame Supported Structure
After a roof is constructed with steel structure or integrated
material, tense fabric will be covered above the roof and. As the
supporting structure below the roof is highly stable, the design
of roof is simple and there are few limits for the position of the
poen. Moreover, such structure has high profit, and could be widely
used in any size space.
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| The Upper and Lower Membrane at No. 11 Greenland |
2. Tension/Suspension Structure
Tension/suspension structure is constructed with fabric, wire rope
and supporting pole. It achieves the firm form through the tension
produced by wire rope and supporting pole. Tension structure not
only has creative, innovative and graceful outside appearance, but
conveys the spirit of membrane structure best. In recent years,
the wire cable net which is consisting of cable and compressed material
and serving to support the fabric above has been largely used in
the large span space. The structure has characteristics such as
precise construction, powerful structure and great expressivities
while it costs slightly higher than the Frame supported structure.
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3. Air Supported Structure
Roof is supported by air pressure, raise indoor air pressure to
a certain pressure with the ventilation system, create a pressure
difference between indoor and outdoor to stand against outdoor pressure.
As it is mainly supported by air pressure with the help of accessorial
material of wire rope, air supported structure needs no girder or
pole, therefore, more spaces would be created. The advantages of
air supported structures are quick installation and high profit,
but the blower needs to be run 24 hours everyday, and the higher
cost as a result of continuous running and machine maintenance should
be taken into consideration.
Fabric:
Fabric, used in construction of membrane structure, has high
strength, great flexility . It is a base cloth material made from
woven fiber and with coating resin on both sides of it. Base cloth
can be divided into polyester and fiberglass, resin used as coating
material contains PVC, silicon and PTFE, base cloth and coating
material in mechanics have characteristics as follows:
Base cloth——tensile strength, tear strength,, heat-resistance,
longevity, fire-resistance
Coating material——weather protection, dirt-resistance, fabrication,
light penetration
Selection of fabric:
Fabric that used as membrane structure architecture can be classified
into PVC fabric and PTEF fabric according to coating material. Correct
selection of fabric depends on the size, function scale, application,
form, aging and budget of the architecture.
PVC Fabric (PVC-Coated Polyester)
PVC fabric is less expensive than PTFE in material and processing,
it has many virtues of soft texture and easy construction. But it
is not as good as PTFE fabric in intensity, aging, fire-resistance
etc. PVC fabric is made from polyester coated with PVC. The fabric
that is commonly used in architecture is produced by the treatment
of coating as applying several microns acrylic resin on the surface
of PVC, which is in order to improve dirt-resistance. However, after
a few years, PVC fabric will generally turn yellow, and is more
likely to crack. Longevity of PVC fabric is 5～8 years according
to different using surroundings. In order to improve weather protection
of PVC fabric, fabric, which is coated fluoric resin on top of PVC,
to improve its weather protection and dirt-resistance, has been
under researches and development in recent years.
PVDF
PVDF is abbreviated of polyvinylidene fluoride. The material coating
PVDF resin on PVC fabric surface is called PVDF. The difference
between PVDF fabric and common PVC fabric is that the life span
of PVDF is lengthened to 5～10 years.
PVF
PVF is abbreviated of polyvinyl fluoride.fabric is laminated with
lamellate PVF on top of PVC fabric. Compared with PVDF, it is more
wear-resistant and dirt-resistant. But it costs more than PVDF.
PTFE Fabric (PTFE Coated Fiberglass)
PTFE fabric is a material coated polyvinylidene fluoride on fiberglass
textile. Comparing with PVC fabric, PTFE has great virtue of longevity,
dirt-resistance and fire-resistance. However, high expense of material
and processing, low flexility are the defects. In order to prevent
fiberglass breaking, it requires a professional and complete plan
in processing, folding, packing, construction techniques.
Longevity : PTFE of coating
material is extremely stable in acid, alkali, and ultraviolet radiation
conditions. It is not easy to discolor or to be broken. After several
years application, fiberglass intensity and tensility remain strong.
Generally, the fabric is white and has a high light penetration.
The life span reaches more than 25 years.
Dirt-resistance : As coating material
is polyvinylidene fluoride; surface frictional coefficient is low,
thereby, it could be cleaned by rainwater and benign for the environment.
Fire-resistance : PTFE fabric is in
accordance with all characteristics, stipulated in the National
Fire-Resistance Testing, and it can replace other roof materials
for the same purpose.
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