what size structure is required, steel buildings tend to fail the aesthetics test, generally offering poor lighting and acoustics. By contrast, the interior environment inside a fabric building offers a softer feel, better acoustics with less echo, and much improved lighting due to the reflective properties of the fabric material. People who’ve never set foot inside a fabric sports structure often comment that the atmosphere exceeds their expectations. While having an attractive venue is certainly beneficial to those using or visiting the building, engineers and architects will also take notice that the same materials used to create that welcoming atmosphere are actually serving another purpose in helping to meet building codes. For projects where state or local energy codes must be met, a rigid-frame design allows building suppliers to easily apply insulation – typically with R values ranging from R-19 to R-30 – along the interior of the structure. The insulation is secured and then covered with a fabric liner that is actually the same type of fabric used for the exterior cladding. Polyvinyl chloride (PVC) has the been the primary fabric of choice for sports facilities for many years because of its durability. The fact that users can select different colors of fabric to match their team, school or organizational branding is also a selling point for fabric in general. Leg - acy Building Solutions offers a newer fabric called ExxoTec™ PVC that delivers more durability and a longer life expectancy, due to the added layers of primer and lacquer around its high-strength woven fabric. To install the fabric, Legacy relies on its patented fabric attachment system that uses half-inch diameter bolts to clamp a keder rail to the top flange of the structural steel frame. Fabric panels are then slid through the keder channel to connect to each beam. This process allows fabric panels to be pulled into place with the properly calculated horizontal and vertical tensions. Wider fabric panels are used for the interior than the exterior of the building, but otherwise the process is the same both outside and inside. With the interior liner tightly secured, maintenance concerns for the fabric cladding itself are practically nonexistent. Behind the Scenes For many industries, the I-beams in a fabric building are left exposed and may require some kind of treatment to protect the steel. Since the structural frames in most fabric-cladded sports facilities are encap - sulated by insulation and liners, typically a primer coating is all that needed to treat the beams. That said, building users in coastal locations or who experience high humidity conditions due to their facility application – such as a swim - ming pool – could consider epoxy paint for I-beam treatment to protect against corrosion. Because the steel beams are permanently out of view, some users might choose this option purely for the peace of mind of knowing that the structural frame is well protected. It is worth noting that the rigid frame building design allows for effective passive ventilation within the walls. Ridge and soffit vents use the natural movement of warm airs to help remove moisture from the insulation cav -
ity, another key piece in meeting building codes for a given environment. Hanging Tough Because of the airtight nature of a lined fabric building, air flow is very important, and passive ventilation alone is not enough for most athletic structures. Users will need some sort of mechanical means to at least move air, if not also heat or condition it. Often this means the inclusion of fans or an HVAC system suspended from the building frame above. For a rigid-frame design, supporting hanging loads like HVAC, fire sup - pression systems and lighting isn’t difficult, although it does need to be considered in the original design. Engineers use finite element analysis software to calculate the stresses for each individual I-beam, rather than over-engineering the entire structure and adding unnecessary cost. Likewise, many sports facilities need to accommodate items such as scoreboards, video platforms, court dividers and netting. Some will even need to add mezzanines for spectator seating. By working with the customer to account for every potential collateral load, building de - signers can simply modify the rigid frame to add the necessary strength for those loads. Added Touches While project managers may be primarily focused on getting the most bang for the buck from a fabric building, of course it’s also common to need to appease certain stakeholders with additional flourishes, such as exterior facades containing brick or stonework. While these elements will add cost, the straight sidewalls of a rigid-frame structure do make it possible to easily include these types of touches. Another possibility with I-beam design is adding a fabric-clad addition to the gabled end of an existing structure. Designers need to consider snow loads and rain runoff for the original building and new addition, among other compatibility factors, but for situations where expansion is a more cost-effective solution than new construction, it often can be done. Built Fast, Built Right Rigid-frame fabric buildings can also be completed in far less time from start to finish than traditional brick-and-mortar buildings. While the time to build the framework is similar for a fabric building and a metal-clad structure, fabric panels can be applied in one-third the time needed to screw down metal siding. A big reason for the overall reduction in fabric building lead time is that companies like Legacy are full-service suppliers who can handle every step in the process from start to finish. By employing their own design engineers, manufacturing fabric panels and I-beams in their own facilities, and sending their own in-house professional installation crews to every jobsite, these companies can ensure full quality control and constantly keep projects moving, without any of the unexpected delays experienced by those relying on outside vendors. All things considered, tension fabric structures offer exceptional value for sports venues large and small. From proven structural integrity to a high level of interior finish and craftsmanship, rigid-frame fabric buildings make it possible for any entity to obtain a facility they can be extremely proud of, without breaking the bank.
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csengineermag.com
DECEMBER 2021
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