The mattress of the Montreal roof is made up of 64 sections, each made up of nets and two membranes. It can be easily assembled on the ground. In addition, LED lights can be inserted inside the envelope to create lighting effects and make the stadium more attractive for major events such as concerts of international stars, for instance. In the same vein, dual winches that are invisible from the ground but constant and stationary are inserted inside the structure so that the roof can be adjusted if necessary.
Various structures can be attached to it, such as lighting racks or speakers for concerts and various other events. A section of the roof could also be opened to the public by converting a secure section in a sort of giant playground.
Finally, this solution is also the most affordable at the current time. This is normal because since air is used to stiffen the structure, it is possible to use less costly materials that are lighter than PTFE. Finally, assembly and elevation do not require cranes or spider-men of any kind, further reducing costs. In the long-term, maintenance costs will be insignificant for such a durable roof. The mattress sections are also covered by another membrane that can withstand weather, which can also be replaced in individual sections.
This provides the other components with an unlimited lifetime. Find out more. Increasingly prevalent, plastics not only address the basic requirements of sports facilities like athlete- and spectator- safety, meeting sporting standards and letting athletes up their game Home Themes : Expert views. An inflatable roof on the Olympic Stadium in Montreal, Quebec. Can you tell us about the various problems encountered?
This lead you to offer your services. Can you describe your solution? And this is enough to keep the whole structure up? What role does air play? We call this method of inflatable structure design and production - airflow, just like that of a bouncy castle. Bouncy castle are made with a heavier grade material, usually heavyweight PVC for larger pieces of a polyester called Oxford cloth for home use products that can be bought online or at supermarkets and stores.
The same principle applies, the air is generated by a usually high powered fan or blower and is circulated into a structure with 2 membranes. These membranes then form a shape with internal ribs or straps to form a shape.
Components of an inflatable structure:. Main material, flame retardant, strength tested and inherent rip stop properties nylon. A heaver material for harder wearing areas such as areas that are in contact with the ground, usually a PVC. Internal ribs or straps that help make the shape, usually made out of similar nylon or polyester.
Stitching or sewing thread. This has to be heavy-duty to cope with the pressure from the inflation. Zips, for areas to access the inside of the structure and for additional extras such as doors. Risky walk in the snow Blowing away the snow and meltwater without causing a fabric tear is exactly what engineer Maki tried to do on December 11 at the Metrodome.
He and six other workers were on the roof, melting snow with water from fire hoses. The Metrodome's roof—which is Teflon-coated fiberglass and weighs approximately metric tons—is inspected every three years by tensile structure contractor Birdair, Inc. About 5 A. The inner liner has drain holes which were not lining up with the outer fabric so the panel was not draining as we heated the building.
We attempted to drain it by shooting the lowest point with a shotgun slug; however, that action caused the panel to rupture anyway. Although investigations are ongoing, Maki says the first panel tear was "obviously" snow-related, and then a shift of strain to the center of the dome caused the next two ruptures.
Moore, an engineering and consultancy firm in Houston, has been retained to investigate the Metrodome incident, but is not allowed to comment. He says, however, that Geiger—whom Griffis called a "brilliant" engineer—would have agreed that air-pressurized dome technology is outdated.
Even though such structures have advantages—particularly, being lightweight, of high strength and low cost—maintaining such facilities is not nearly as attractive as it was a couple decades ago. The risk of deflation alone has proved problematic, and has occurred several times at inflatable dome facilities, particularly due to snow loads.
Griffis also points out that maintenance costs tend to be higher than many owners want to pay; for example, maintaining air pressure can be both laborious and expensive.
Maki says the Minnesota Vikings, who didn't make the NFL play-offs this season, are in serious discussions for a new stadium; whether that means moving to a new location or not is uncertain, but the Metrodome's days as a home for a professional football team could be numbered.
Tensegrity structures are supported primarily by high-strength cables whose tension forces are balanced either by air or other support structures, Griffis says. Griffis adds that air-supported structures such as the Metrodome are a particular class of tensegrity structures supported by differential air pressure. Editor's Note: Scientific American contacted Birdair , the company that manufactures the fabric dome. After calls were twice referred to their legal department, messages ultimately went unanswered.
But, according to Gossen, deflation is an inevitable concern with an inflatable roof, especially in cold weather climates.
However, the roof was built in a deflated position with its cables at least 30 feet above occupied space at all times, so no one inside the Dome would be harmed if the roof were to deflate. The inflatable structure does have several advantages despite its weight restrictions and maintenance requirements.
Along with being inexpensive, the inflatable roof allows for natural light to enter the facility, making it an attractive option when first constructed. More natural light meant less demand for electric light and heat in the building. In a stadium the size of the Dome, heating and lighting the facility is pricey without any source of natural light. The sunlight that shines through the fabric-based roof also creates more of an outdoor stadium atmosphere.
Event Manager Mike Kravec agrees the facility has both strengths and weaknesses. While the inflatable roof caters to large crowds and Northeastern weather conditions, its inability to support heavy external loads presents a challenge when it starts to snow.
The roof requires constant care and cannot be used to hang heavy objects, as they would displace the air-pressure in the fabric. This limits the events the Dome can hold, as most large bands have sound systems designed specifically to hang.
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