Air-Supported Dome is a volume enclosing membrane which carries load developed from the tensile stresses.Its stabilization is done by pre-stressing the membrane by internal air pressurizing. Air-Supported Domes sizes are usually from 1.000m2 to 15.000m2. These structures can create artificial environments adaptable to human use. The Air Dome structures are bound to increase in popularity, owing to the tremendous freedom they provide to the architects in designing large free spaces within them.Although Air-Supported structures have been used by mankind for thousand of years;it was only introduced in the building technology about 40 years ago.
Its principle is the use of relatively thin membrane supported by an air-pressure difference .Through increasing the inside air pressure not only the dead weight of the membrane is balanced , but the membrane is stressed to a point where it cannot be indented by asymmetrical loading.
It consists of a membrane (enclosing a functionally useful space) which is supported by a very small internal air pressure difference. The internal volume of an air dome is consequently at a pressure higher than atmospheric.
Airlocks or revolving doors help to maintain the internal pressure. Air must be constantly provided.They are either anchored to the ground or to a concrete wall so that leakage is prevented. They have relative low cost and they can be installed easily. Life span of 20-25 years.
General characteristics of Air-supported DOME
- 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
- There is no theoretical maximum span .
- To span a distance of 1km for a normal building is hard while such spans are quite possible for Air Dome.
- Air Dome structures are safer than any other structure.
- They are earthquake resistant.
- They are fire resistant structures.
- Also suitable for temporary constructions.
- It is not expensive compare to other types of clear span buildings.
- Membrane material is completely recyclable.
- Energy efficient due to insulation layer.
- In most cases, the additional air pressure inside the Air Dome is not more than 80-100mm and not less than 60mm.
- Man can withstand pressures between 0.20atm to 3 atm.
Therefore no health hazard is presented by continuous stay in an Air Dome.
Most common membrane material for smaller Air Dome. PVC-coated polyester is common for flexible, smaller Air Dome. The PVC is applied to the polyester fibers using a bonding or adhesive agent. Coated with Teflon to increase resistance to extreme temperatures and UV radiation.
They are high tensile strength, elastic behavior and durable. Coated with Teflon to increase resistance to extreme temperatures and UV radiation.
Air-Supported DOME Components
- 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.
- Doors can be ordinary doors for safety exit, or airlocks.
- Airlock minimize the chances of having an unevenly pressurized environment.
- It is used to supply and maintain internal pressure inside the structure.
- Fans, blowers are used for constant supply of air
- The amount of air required depends on the weight of the membrane material and the wind pressure .
- 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.
Air-Supported DOME Components
Air Dome structures are secured to ground using heavy weights, or attached to a foundation.Weight of the membrane material and the wind loads are used to determine the most appropriate anchoring system.For bigger Air Dome, reinforcing cables are used. For a dependent (roof only) Air Dome the membrane is anchored to the main structure. Generally, Air Dome attaches to a concrete grade beam installed around the perimeter. The grade beam acts as ballast to keep the structure firmly anchored to the ground.
Wind and Snow loads are the primary loads that are acting on Air-Supported Domes. Air Dome structures are anchored very tight to the ground, so no horizontal forces are exerted to the membrane. As Air Dome structures are tensile, the membrane 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. Air Dome structures are designed to withstand wind speed of 120 mph and a snow load of 35 pounds-per-square foot.
General Layout of the Dome with all electro-mechanical equipment is designed.
Calculation note is made by structural engineers. Mechanical engineers calculate the size of fans and air conditioning system needed. Software engineer develops the control software
Standard Membrane are made of PVC coated polyester fiber fabrics with a PVDF (polyvinylidene fluoride) topcoat to maintain the aesthetic value and structural integrity of the dome.Membrane is UV resistant, with long term dirt resistance. All membranes are fire retardant (B1 / DIN 4102)
Weaving: high density for higher strength
Anchoring system is used to fix the membrane on the concrete grade beam XY cable system is made of continuous cable from anchor to anchor. All cables are flameproof, corrosion resistant and linked to the membrane by sleeves. Cables are comprised of galvanized wire rope, typically coated with polyethylene.
Central air conditioning system The cold air is supplied inside the air dome by the ventilation unit.
Distribution cabinet machine The hot or cold air go inside only (this is usually for big area)
There are two types of LED lighting systems, which are used as per the requirements of the structure and the purpose for which the structure is built.
Stainless steel revolving door, Stainless steel emergency door, Electric / Manual Logistic door
Advantages of Air DOME
- Construction costs are lower than any other roof structures
- Covers large spans without internal supports
- Light weight and compact folding membrane
- Climate and air controlled environment
- No foundation is required
- Rapid fabrication and short erection time
- Low maintenance and operating cost
- Air Dome structures have proven long-term durability
- Can be equipped with different sports flooring
- Can be equipped with modular grandstand
- Can be equipped with modular offices, changing rooms
- Can be easily dismantled, transported and re-erected
Air-supported Dome Applications
Multi-purpose sports centers, Expos & trade shows, Conferences, Conventions, Retail space, Charity events, Fundraisers, Campaign headquarters, Office space, Community centers, Religious events, Camps and clinics, Fairs & festivals, Cafeterias & dining halls, Academic space, Reception venue, Theater, performing arts & gallery space, Annual events, Seasonal or holiday events & activities, Badminton courts, Tennis courts, Hockey courts, Athletic tracks, Electric Go-kart tracks, Pools and water parks, Golf driving range, Volleyball courts, Handball courts, Gym, Climbing wall
Industrial plants, Food processing plants, Storage activities (grains, …)