Series continues on Fabric Structures: A to Z
- Biaxial Testing
A bandshell is a large, outdoor performing venue typically used by bands and orchestras. The roof and the back of “the shell” protect musicians from the weather and reflect sound through the open side and out towards the audience.
They can be made of concrete, wood and just about anything but my favorite is fabric (of course). Fabric Structure bandshells can be temporary or permanent and come in all shapes and sizes. They can even be designed to work indoor.
Personally, I like the temporary bandshell from Anchor Industries and Tentnology. Both good buddies of mine. If you need to go permanent, I like to bring along FTL Design Engineering Studio with me (FYI: I use to work there myself). They have a lot experience with these kind of structures.
It’s hard to talk about Birdair because they are my biggest competitor but my role is to promote the industry and encourage more use of fabric structures worldwide. Birdair is the most recognized name associated with large-scale fabric structures. The have been involved in the many of the large-scale structures built for Olympics, World Cups and a number of sports stadiums. They have recently made news because they were the roof manufacturers of the Metrodome in Minneapolis and Skyline Stage at Navy Pier in Chicago which both collapsed during a2010 winter storm in the midwest.
Birdair is located in Upstate New York but is owned by the Japanese company Taiyo Kogyo. They advertise heavily in Architectural Record in order to be “first in mind” with Architects but there is no such thing as “birdair structures”. The company which started in 1957 under the direction of Walter Bird and rose to prominence in the 1980’s with projects like the Haj Terminal is a skeleton of itself with many of the designers, engineers and employees now retired or gone elsewhere to work.
“Companies don’t build projects, people do”. Be comfortable with the people you want to work with before you proceed to build a fabric structure.
No two fabrics are alike. They stretch differently and subsequently require what is called a biaxial test. A Biaxial test stretches a membrane in both the warp and fill direction to determine the elongation behavior under certain loads.
How much do you need to know?
As an owner or designer of a small-scale structure, you should at least ask to make sure one has been done if not on your specific fabric but on a sample of the material you have purchased. On bigger projects (i.e. stadiums), a biaxial should be done and recorded. Anything to do with fabric, testing and performance, I always go to Tensys. They are the best.
Next I will comment on cables, catenaries, cutting patterns and COST.