A brief presentation on Pneumatic Structures Building Construction & Materials

1. GROUP II
AKASHMATTHEW | BSSANJANA | LAVANYACHOPRA | KEERTHIREDDY | SNIGDHAJOHAR | TANISHAGANAPATHY | THANGSONTOMBING
PNEUMATIC STRUCTURES
BUILDING CONSTRUCTION & MATERIALS VI.

2. • Pneumatic structure is a membrane
which carries load developed from
the tensile stresses.
• Its stabilization is done by pre-
stressing the membrane either by
a) Applying an external force
which pulls the membrane
taut
b) Internal pressurizing if the
membrane is volume
enclosing.
Such structures are called “pneumatic
structures”.
• These structures can create artificial
environments adaptable to human
use .
• The pneumatic forms are bound to
increase in popularity, owing to the
tremendous freedom they provide
to the architects in designing large
free spaces within them.
INTRODUCTION TO PNEUMATIC STRUCTURES.
• The word pneumatic is derived from the
greek word “pneuma” (meaning breath of
air), thus these are the structure which are
supported by air.
• Although pneumatic structures have been
used by mankind for thousand of years; it
was only introduced in the building
technology about 40 years ago.
1. Its principle is the use of
relatively thin membrane
supported by a pressure
difference.
2. Through increasing the inside
air pressure not only the dead
weight of the space envelope is
balanced, but the membrane is
stressed to a point where it
cannot be indented by
asymmetrical loading.
PRINCIPLE

3. • They have air higher than the atmospheric pressure supporting
the envelope.
• Air locks or revolving doors help to maintain the internal
pressure.
• Air must be constantly provided.
• Life span of 20 – 25 years.
• Relatively low cost.
• They are either anchored to the ground or to a wall so that
leakage is prevented.
• They have relative low cost and they can be installed easily.
TYPES OF PNEUMATIC STRUCTURES.
• Supporting frames consist of air under high pressure.
• Internal pressure of building remains at atmospheric pressure.
• There is no restrictions in number and size of openings.
• It has the ability to support itself.
• They have potential to support an attached structure.
AIR INFLATED
STRUCTURES
AIR SUPPORTED
STRUCTURES
It consist of a single membrane (enclosing a functionally useful
space) which is supported by a small internal pressure difference.
The internal volume of a building air is consequently at a pressure
higher than atmospheric. It is supported by pressurized air contained within inflated
building element. The pressurized air in the pillow serves only to
stabilizing the load carrying membrane. The covered space is not
pressurized.

4. • The weight of the structure as
compared to the area it covers is
very less.
• The weight of the membrane roof,
even when it is stiffened by cables,
is very small.
• Low air pressure is sufficient to
balance it.
GENERAL CHARACTERISTICS OF PNEUMATIC STRUCTURES.
LIGHT-WEIGHT
• There is no theoretical maximum
span.
• To span a distance of 36 km for a
normal building is hard while such
spans are quite possible for
pneumatics.
SPAN
• Pneumatic structures are safer than
any other structure. Otherwise, a
proper care should be taken while
establishing.
• They are fire resistance structures.
SAFETY
• Suitable for temporary
constructions.
• 1 km² area can be brought down in 6
hours and can be establish in less
than 10 hours.
QUICK ERECTION & DISMANTLING
• It is not expensive when it is used as
temporary structures.
ECONOMY
• If envelope is made up of
transparent material, good natural
light enter into the structure.
• Around 50% – 80% of sunlight can
be obtained.
GOOD NATURAL LIGHTING
• In most cases, pressure of not more
than 80-100mm and not less than
60mm.
• Man can withstand pressures
between 0.20 atm to 3 atm.
Therefore no health hazard is
presented by continuous stay in a
pneumatic structure.
HUMAN HEALTH

5. • They can be made up of different
materials.
• Cannot be used as one continuous
material.
• Material are seamed together by
sealing, heat bonding or mechanical
jointing.
• The design of the envelope depends on
an evenly pressurized environment.
SYSTEM COMPONENTS.
ENVELOPE
• They act as the supporting system.
• They experience tension force due to
the upward force of the air.
• Can be placed in one or two directions to
create a network and for better stability.
• They do not fail since they are pulled
tight enough to absorb the external
loads.
CABLE SYSTEM • It is used to supply and maintain
internal pressure inside the structure.
• Fans, blowers or compressors are used
for constant supply of air.
• The amount of air required depends on
the weight of the material and the wind
pressure.
PUMPING EQUIPMENT
• Doors can be ordinary doors or
airlocks.
• Airlock minimize the chances of
having an unevenly pressurized
environment.
ENTRANCE

6. • Pneumatic structures are secured to ground using heavy
weights, ground anchors or attached to a foundation.
• Weight of the material and the wind loads are used to
determine the most appropriate anchoring system.
• For bigger structures, reinforcing cables or nets are used.
• For a dependent pneumatic structure (roof only air
supported structure) the envelope is anchored to the main
structure.
• When anchoring is done to soil, the cable is attached to the
anchor directly inserted and frictional forces of the soil to
hold it down.
• Soil anchoring systems include screw, disk, expanding
duckbill and arrowhead anchors.
SYSTEM COMPONENTS.
FOUNDATION

7. • Wind and Snow loads are the primary loads that are acting
on pneumatic structures.
• They are anchored very tight to the ground, so no horizontal
forces are exerted to the envelope.
• As pneumatic structures are tensile, the envelope has the
ability to gain stiffness in order to withstand the loads acting
on them.
LOADING.
• Wind loads produce a lateral force on the structures and
snow load causes downward forces on envelope.
• Pneumatic structures are designed to withstand wind load of
120 mph and a snow load of 40 pounds/yard.
AIR SUPPORTED STRUCTURES AIR INFLATED STRUCTURES

8. CLASSIFICATION OF PNEUMATIC STRUCTURES.
• Pneumatic Structures use either positive pressure or negative pressure.
• In Positive Pressure System, the membrane is always curved outwards, whereas
in Negative Pressure Systems the membrane is curved inwards.
• Being curved inwards there is a tendency of water logging & snow accumulation.
• Moreover, negative pressure systems require high supports at the edge or in the
center which makes it more expensive.
TYPE OF DIFFERENTIAL PRESSURE
Pneumatic Structures can be further subdivided as:-
A. Type of Differential Pressure
B. Degree of Differential Pressure
C. Type of Surface Curvature
D. Proportions
LOW PRESSURE SYSTEMS
These systems are provided with low pressure air; hence have to be provided with
continuous supply of air. Example: Air Supported Structures.
HIGH PRESSURE SYSTEMS
Used for easy erection & dismantling; the pressure difference is b/w 2000-7000mm of
water pressure (100 to 1000 times) low pressure systems.
These high pressure air inflated systems are either having a single valve system or a
double valve systems which avoids it’s collapse.
DEGREE OF DIFFERENTIAL PRESSURE
AIR SUPPORTED STRUCTURES
AIR INFLATED STRUCTURES

9. CLASSIFICATION OF PNEUMATIC STRUCTURES.
These structures can also be classified according to the
types of curvature on the outer surface,
a. Single curved
b. Doubly curved in the same direction or
synclastics
c. Doubly curved in opposite direction or
anticlastic
TYPE OF SURFACE CURVATURE
On the basis of different proportions, pneumatic structures
can be:-
a. Two dimension of similar size and one larger
dimension
Example: Tubes, Masts, Columns,Towers
b. Two dimensions of similar size and one smaller
dimension
Example: Cushions , Lenses, Mattresses
c. Three dimensions of similar size
Example: Balloons, Balls, Spheres, Bubbles
PROPORTIONS
DOUBLY CURVED IN THE SAME
DIRECTION
DOUBLY CURVED IN OPPOSITE
DIRECTION

10. • They high tensile strength, elastic
behavior and durability.
• Coated withTeflon or silicone to
increase resistance to extreme
temperatures and UV radiation.
MATERIALS.
FIBERGLASS
• Most common envelope material
for smaller structures.
• PVC-coated polyester is common
for flexible, smaller air-supported
structures.
• The PVC is applied to the
polyester using a bonding or
adhesive agent.
POLYESTER
• It is very energy efficient because
of transparency, insulation and
UV resistance.
• It is also light weight has an
lifespan on 20 years and is
recyclable.
ETFE
(ETHYLENE TETRAFLUOROETHYLENE)
• Vinyl-coated nylon has more
strength, durability and stretch
than polyester.
• They have a higher cost.
NYLON
ENVELOPE MATERIALS

11. MATERIALS.
• Steel wires are twisted into strands which are then twisted
around a core to form the cable.
STEEL CABLES
• Materials for ballasts of smaller structures include sand bags,
concrete blocks or bricks.
• The ballasts must be placed around the perimeter of the
structure to evenly distribute the load.
BALLASTS
ANCHOR MATERIALS
The anchor material depends on the application and size of the pneumatic structure.

12. APPLICATIONS.
SPORTS & RECREATIONAL CENTRES
Ability to span great distances without
beams and columns.
MILITARY STRUCTURES
For storage, for emergency medical
operations &To protect radar stations from
weather conditions
EXHIBITION & CONVENTION CENTRES
STRUCTURES FOR BOTANICAL GARDENS,
ZOOLOGICAL GARDENS, GREENHOUSE, HOTHOUSE
TRAVERSING BRIDGE STRUCTURES

13. ADVANTAGES & DISADVANTAGES OF PNEUMATIC STRUCTURES.
ADVANTAGES DISADVANTAGES
• Light weight
• Covers large spans without internal supports
• Rapid assembly and have low initial and operating cost
• Portability
• Need for continuous maintenance of excess pressure in the
envelope
• Relatively short service life
• Continuous operation of fans to maintain pressure
• Cannot reach the insulation values of hard-walled structures
CONCLUSION a) Pneumatic structures have found wide range of application.
b) They are best suited for small and temporary construction.
c) They can be quickly erected and dismantled.
d) Provoke fascination among observers and bystanders.