Regardless of the industry, nobody is a stranger to maintenance. From equipment to vehicles to facilities, these capital investments will likely need to be maintained. However, the level of required maintenance can vary greatly depending on the solution involved. A common engineering solution for building users in markets such as government, aviation, recreation, commodity storage, and more is to utilize tension fabric structures. Fabric buildings have typically been chosen because of their quicker installation schedules and overall cost- effectiveness. Thanks to better engineering and improved materials, many of today’s fabric structures are practically maintenance-free as well, to the point where there’s almost zero upkeep actually needed for The biggest advancement for modern fabric buildings came several years ago when Legacy Building Solutions took the step of marry- ing together a tension fabric membrane with a structural steel I-beam frame, essentially bringing a conventional construction look to the fabric building industry. Historically, fabric structures used a tubular web truss frame, charac- terized by a “hoop” shape with curved sidewalls. The appearance of a hoop structure wasn’t the issue. The main problem arose from the inconsistent engineering of truss designs. Different engineers often came to different subjective conclusions about the integrity of a given web truss framing system. A building collapsing due to an unidentified failure point was a real possibility. a quality fabric building. Rigid Steel Framing By shifting toward rigid-frame, tapered I-beam design that was known and proven in the engineering community, newer fabric buildings re- moved any lingering question marks about the strength and longevity of the frame. This also opened up many possibilities for fabric build- ing users, who could now have their structures customized to exact dimensions and other parameters, thanks to the design flexibility that is Beyond shear strength, structural steel I-beams have the advantage of being completely solid steel and, therefore, better suited to surviving high-humidity environments or just the basic long-term effects of cor- rosive elements over a building’s life cycle. By contrast, many tension fabric structures in the industry use hollow-tube frames that are vulner- able to corrosion originating inside the tube. In effect, truss frames can experience corrosive damage long before anyone can see it. inherent with a rigid-frame approach. Preventive Corrosion Protection Although fabric liners are available to provide a finished building in- terior in certain applications, in many industries the steel beams are Holding Their Own Today’s fabric buildings are engineered to keep maintenance to an absolute minimum By Eric Donnay
left exposed inside a fabric building. A variety of treatment options are available as a preventive maintenance measure against corrosion for the frame and other steel components. Hot dip galvanizing has been among the most popular techniques. There is, however, a significant difference between galvanizing protec- tion for solid beams and hollow tube frames. Tube frames are inline galvanized, meaning they’ve already been galvanized at the factory. The building supplier then welds the frames later, which diminishes the value of the galvanization where new heat is applied. With rigid I-beams, galvanizing occurs post-production, so the beams are already welded together before receiving topical treatments. The same holds true for a recently introduced corrosion barrier offering for rigid frames – epoxy paint. Epoxy coating creates an actual barrier between corrosion and the steel beam, where galvanizing only slows down the corrosion process by sacrificing itself, allowing a thin zinc coating to be eaten away over time. Epoxy paint is quickly becoming recognized as a worthwhile investment to help extend the life cycle of buildings and equipment. Fabric Longevity One area where corrosion is definitely not a factor is with the fabric cladding material itself. Whether using polyvinyl chloride (PVC) or polyethylene (PE), architectural fabrics are not susceptible to corroding. Tension fabric has long been known to provide a variety of opera- tional benefits. Its translucency allows for natural daylighting inside a building. Unlike metal sheeting, fabric has thermally non-conductive properties, helping to keep building interiors warmer in the winter and cooler in the summer. However, like any single-layer material, if it’s necessary to eliminate condensation or provide heating or cooling, insulation and a fabric liner are definitely needed to provide superior results and meet energy code requirements. Fabric’s benefits can be enjoyed for many years, but the type of fabric used can have a big impact on the roof’s overall longevity. PE fabric is the most widely used material in the industry, while PVC has been commonly reserved for higher end projects due to its price point. How- ever, owners have realized that PVC’s long-term benefits and increased lifespan effectively offset the initial investment.
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csengineermag.com
January 2021
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