By Jeff Williams
When talking to children of service members about where they grew up, there’s a decent chance you’ll hear the term “military brat” as they describe how they moved around from place to place. While they often wear the term itself as a badge of honor, for them to actually pinpoint where they are from is difficult, as every home was inevitably temporary.
“Temporary” also happens to be a key word when it comes to the wide-ranging and ever-growing facility needs on bases around the world. Whether supporting military operations themselves or the people working and living on the bases, new facilities are often needed quickly – or at least much faster than is typical when having to cut through government red tape and secure all the proper approvals.
So how can one expedite the construction of a new building for a military application? There is no universally correct answer to that question; however, building projects tend to move along faster when the intended structure comes with a temporary classification.
A temporary structure can mean a wide variety of things. For example, it could refer to an inflatable building that is up and ready to go in only four hours. But for this discussion, the definition will include permanent, semi-permanent or relocatable facility solutions that happen to be categorized as temporary – such as tension fabric buildings.
Fabric membrane structures have been around for decades as a dependable, cost-effective option for applications ranging from equipment maintenance shops to material storage sheds and aircraft hangars. Historically, fabric buildings were indeed more of a temporary solution, with the fabric roof cladding averaging a lifespan of about 10-15 years at best. Today, durable polyvinyl chloride (PVC) fabrics, such as ExxoTec™, typically have thicker coatings and better UV inhibitors, extending the expected life of a fabric roof to around 30 years.
While an engineered fabric roof reflects UV rays, the material still offers up to 16 percent translucency to take advantage of natural light. Direct sunlight produces approximately 10,000-ft candles of illumination, so fabric with 10 to 15 percent translucency can provide a significant benefit for lighting within a building.
Many buildings will still require artificial lighting at night, while others demand interior insulation to meet local energy codes. But even an insulated structure will reap the benefit of a fabric roof’s high solar reflectance, which keeps the roof cooler by deflecting sunlight and heat away from the structure. Fabric has thermally non-conductive properties which also reduce the possibility of heat absorption into the structure.
While the enhancement of fabric itself was a good step forward, the bigger technological advancement in fabric buildings in the last ten years came when Legacy introduced rigid-frame engineering to the industry. In contrast to fabric structures that were traditionally erected using hollow-tube, open web truss framing, rigid-frame designs utilize the same structural steel I-beams found in most conventional industrial construction projects.
Ironically, one advantage of the rigid-frame design is that it provides more flexibility when customizing the overall size and alignment of a fabric building. The exact length, width and height of a building can be specified down to the inch. Offset peaks, a wide variety of door options, variable column heights, insulation, ventilation, fire suppression systems, and many other unique features can also be applied.
Additionally, unlike the web truss structures of the past, which had a “hoop” style that minimized the usable space along the sidewalls, solid beam engineering provides straight sidewalls, clear spans and tall overhead clearances that allow every square foot to be used.
On top of it all, the procurement process does not take any longer, as all unique building requirements can be accounted for in the original custom design.
NO TENTS ALLOWED
For many, the term “fabric structure” immediately brings to mind a tent. But rigid-frame engineering has effectively nullified that comparison. In reality, modern day fabric buildings have much more in common with traditional architecture – they are conventional buildings that just happen to have a fabric membrane.
While the presence of fabric or “soft wall” cladding allows these buildings to be classified as temporary, the quality of construction is where well-engineered fabric structures separate themselves. All Legacy buildings are designed and engineered to International Building Code (IBC) to meet emission and environmental load requirements. Simply put, all conditions and parameters are addressed in the initial engineering phase. For example, a building in Florida could be designed to meet 165-mph wind loads, while a structure on a base in Alaska could be built to withstand 110-mph ground snow loads.
Rigid frame buildings seemingly have more a permanent feel due to their architecture and functional enhancements such as gutters, ice breakers, or even steel sidewalls. But these structures can still be disassembled and relocated as needed. In a sense, they’re exactly as permanent or temporary as the owner wants them to be.
This engineering style also works as a modular concept that makes it simple to expand or contract to a larger or smaller building footprint on the same site. Using a motorpool application as an example, if a new mission requirement dictated that a battalion-sized structure be expanded to accommodate a brigade-sized fleet, the end of the original building could be easily removed to add the appropriate square footage.
Not all military structures require as thorough of a design. Solid beam engineering also works well when quickly constructing a simple shade shelter for vehicles, equipment, wash-down stations, POL areas or aircraft.
FABRIC BUILDINGS IN USE
Retail Facility – Camp Lemonnier, Djibouti. With temperatures in the region regularly reaching over 100°F, it was critical that the building envelope provide an environment where goods could be safely stored, and where military members and their families could shop comfortably. The structure also needed to provide the flexibility to relocate and accommodate future growth at the base. Legacy designed and constructed a 70 by 160-ft facility with a fabric roof on a rigid steel frame. The building contains R-30 insulation, along with a complete heating and cooling system. The steel frame supports these systems, in addition to a duct ventilation system, while the fabric cladding minimizes thermal bridging to help the cooling system run more efficiently. Legacy’s in-house installation crew completed its portion of the construction – including the insulation, interior liner and windows, in about a month.
Water Treatment and Purification Building – Wright-Patterson AFB, Ohio. When the Wright-Patterson Air Force Base needed a building for water treatment and purification, Legacy’s rigid beam engineering came in handy to meet the precise building dimensions. The structure measured 33 by 92-ft with a 26-ft side column and 31-ft peak height. The interior featured R-30 insulation with white polyethylene fabric liner. Eighteen-inch overhangs included mesh soffits, gutters and downspouts. The exterior was clad with gray fabric, and the structure was designed for 20-lb snow loads and wind loads up to 90-mph.
Solar Ship Hangar – Brantford, Ontario Municipal Airport, Ontario, Canada. Although not a military building, the Solar Ship hangar at the Brantford, Ontario, Municipal Airport provides an excellent blueprint for potential military aircraft hangars or other structures where energy-efficient operation is required. The 40,597-ft2 facility was designed by Legacy for manufacturing and storage of Solar Ship’s innovative hybrid aircraft. The key feature is an array of solar panels attached to the roof and estimated to generate 62.4-MWh of energy per year, allowing the building to operate completely off the grid.
Jeff Williams is Vice President of Sales, Legacy Building Solutions; 877-259-1528 or firstname.lastname@example.org.