|As we have stated previously, we are going to be taking the ideas developed in this column over the last couple of years and developing them into design practices. This is how it works. We will provide the basic narrative here for one design practice each week. We will keep it open for comments for one month. After that, we will finish it in formal form and offer it for sale at a modest price. Here is where you come in. If you make a substantive contribution to a standard, the organization for which you work will be granted a pro bono license to use that standard with its current issue number for as long as you like. We have had good response so far! Contribute, please.
This week's: Fabric Roofs (LGM 2013.012.01 when issued)
The biggest performance advantage of tensile fabric structures is its strength to weight ratio, which saves on materials and the cost of supporting a conventional roof, in the building columns and foundations. Tensile fabric structures are lightweight, flexible and have self-cleaning properties making for easy maintenance, which results in considerable cost savings over conventional structures.
To use fabric roofs on paper machine and ancillary buildings.
For external use there are two main choices of coated fabrics: PVC (Polyvinyl Chloride) coated polyester cloth and PTFE (PolyTetraFluoroEthylene) [Teflon] coated glass cloth, with the latter being the natural choice for permanent structures with a design life over 15 years.
PTFE fiberglass coating is chemically inert, capable of withstanding temperatures from -100�F to +450�F (-730C to +2320C). The low-surface free energy of the material results in an electrical grade fabric membrane with aninherent non-stick surface, resists pollutant adhesion and allows rain to clean off most dirt.This inertness, thermal stability and surface properties make PTFE-coated fabric membrane ideal for various weather conditions and fire resistance(withstands temperatures up to 1000oC).The anticipated lifespan of the membrane is 25 - 30 years.
PTFE's fiberglass yarns maintain ultimate tensile strength of 500,000 PSI and a modulus of elasticity of 10.5 x 106 compared to steel, which offers 29 x 106 PSI. Under normal conditions, the fabric behaves elastically and does not undergo significant stress relaxation or creep.
The woven fiberglass gives the PTFE fiberglass membrane its mechanical strength. These filaments, known as beta glass, are the smallest diameter available and provide the membrane with maximum flexibility.
The structural design and shape should incorporate the effects of: Wind, Sun, Fire, Thermal Insulation,Snow, condensation, etc.
1. Birdair Inc. - Tensile Architecture
So, give us your comments by 20 Feb 13, please!
Still open for comments CPVC Dryer Bearing Drains (Open until 13 Feb 13)
Still open for comments Foundation Design Practice. (Open until 6 Feb 13)
And we will be doing something else with the weekly ideas--we will be discussing many of them in a round table discussion at the LGMI Annual Conference January 27 - 29, 2013 here in Atlanta. You can attend in person for free or online for a nominal costs. You will need to sign up soon as openings are limited. Sign up here.
As always, your comments will be appreciated.
Brian Brogdon, Ph.D.
Send us your comments!