THE NATIONAL RIBAT UNIVERSITY

Eng. Mazin Elsayed A. Mustafa

Teaching Assistant

Faculty of Architecture

“ THE AIR INFLATED STRUCTURES SYSTEM ”

CONTENTS :

1. Introduction.2. Air Inflated Structure System

(Pneumatic)

3. Types of Pneumatic Structures.

4. Components & Materials.

5. General Characteristics

6. Natural Loads

7. Advantages & Disadvantages.

Introduction

Membrane Structures that are stabilized by

pressure of compressed air.

Pressure difference between the enclosed

space and the exterior are responsible for

giving the building its shape and its stability.

The pressure should be uniformly distributed

for structural integrity.

Pneumatic Structure

Air Inflated Structure System (Pneumatic)

Round in shape because it creates greatest volume for least amount

of material.

The whole envelope has to be evenly pressurized for best stability.

Pre stressing of membrane can be done either by applying external

force or by internal pressurizing.

Types of Pneumatic Structures

Air Supported Structures.

Air Inflated Structures

• 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.

• 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.

Air Supported Structure

Air Inflated Structures

Supporting frames consist of air under

high pressure.

Internal pressure of building remains at

atmospheric pressure.

There is no restrictions in no. and size of

openings.

They have potential to support an

attached structure.

Materials

1. Envelope Materials

2. Anchor Materials

Envelope Materials :

They should be light weight.

Should have high tensile strength, tear resistance etc.

Fiberglass:

They high tensile strength, elastic behavior and durability.

Coated with Teflon or silicone to increase resistance to extreme

temperatures and UV radiation.

Polyester:

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.

Nylon:

Vinyl-coated nylon has more strength, durability and stretch than polyester

They have a higher cost.

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Anchor Materials:

The anchor material depends on the application and size of the pneumatic

structure.

Steel Cables:

Steel wires are twisted into strands which are then twisted around a core to

form the cable.

Ballasts:

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.

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System Components:

Envelope:

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.

Cable System:

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.

Pumping Equipment:

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.

Entrance Doors

Doors can be ordinary doors or airlocks.

Airlock minimize the chances of having an unevenly pressurized environment.

Foundation

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.

General Characteristics :

Light Weight:

Weight compared to area is less.

Low air pressure is required to balance it.

Span:

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.

Economy:

Not expensive in case of temporary structures.

Safety:

More safer but proper care should be taken.

They are fire resistance structures.

Quick erection and dismantling:

Suitable for temporary constructions.

1 km² area can be brought down in 6 hours and can be establish in less than 10

hours.

Good Natural Light:

If envelope is made up of transparent material good natural light entre into the

structure.

Around 50% – 80% of sunlight can be obtained.

Good Natural Light:

If envelope is made up of transparent material good natural light entre into the

structure.

Around 50% – 80% of sunlight can be obtained.

Theft:

They are very safe structures.

If the air bag is cut with a knife or a pin a big bang is produced.

Natural LoadS:

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.

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 StructureAir Inflated Structure

Advantages & Disadvantage :

Advantage :

Light weight

Covers large spans without internal supports

Rapid assembly and have low initial and operating cost

Portability

Disadvantage :

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

THANK YOU …