wind and rain storm producing a tornado causing destruction. More Extreme Weather Events Challenge Communities and Structures

Extreme weather events seem to be on the rise nationwide, posing challenges to residents, businesses and infrastructure. The National Oceanic and Atmospheric Administration (NOAA) acknowledges what some have been experiencing at home, or have seen played out on TV news reports and on the internet: that extreme weather events are occurring with higher frequency and more severity.

Tougher Local Building Codes Affect Tent Structure Requirements

As building and safety technologies improve, and in recognition of the increasing unpredictability and frequency of severe weather events, some measures have been taken by state and local agencies in recent years to improve the readiness of our infrastructure, including:

  • City, county, state, and federal building codes are being revised to set minimum requirements for structural strength to withstand strong winds and other extreme weather.
  • Businesses, government organizations, and Individuals are recognizing the need for additional safety considerations, including during storm recovery efforts, when deciding on a structure that can protect workers and volunteer teams, supplies, and equipment.
  • Many local building codes are raising wind load requirements and recommendations, particularly in hurricane and tornado prone locations.
  • More decision-makers are choosing to utilize structures that withstand the most severe weather for their storage, instant warehouse, and retail space needs, reducing risk of loss and business interruptions.

To meet increasingly stringent local building codes, temporary structures that are intended for long term use (six months or longer), need to be able to meet these standards. Temporary tent structures in most cases will not meet these tougher requirements. A better option is a highly engineered tension fabric structure (TFS), built to comply with local code requirements, engineered for long term use and designed to withstand tough weather conditions.

Tent Structures Don’t Hold Up in Stormy Weather

Especially for areas subject to severe weather events, fabric structures can be challenged to meet tougher building codes and assure the safety of people and equipment when a severe weather event does occur. Finding a structure that can meet extreme weather situations is essential for safety and successful usage.

When compared to tension fabric structures, which are designed with the strength and stability for long-term, all-weather uses, temporary tent structures are most suitable for short events held in good weather conditions. Like a tension fabric structure, tent structures may have a large footprint and use an aluminum extrusion, however the beam is smaller in size and not as strong. Importantly, tent structures are missing the key design elements of horizontal tension on the fabric and curved legs that provide the stability and strength of the tension structure to withstand very high winds and cope with heavy snowfall or hail events. The temporary tent structures may also use hinged connections at the peak and legs, which make for a fast install, but are not as strong and tend to rattle in the wind and leak in rain or snow.  Tent structures create no internal resistance to outside air changes, but may give way when strong pressure is exerted on one or more sides of the structure, making a high wind event a potential risk of failure of the tent structure.

tension fabric and aluminum frame structure over home reconstruction site

While inexpensive tent structures are often used for short-term shelter and storage space for outdoor projects, if left in place for too long, these structures will face potential catastrophic failure if a weather event does occur. Typically these structures may claim to meet wind load requirements, but will only do so for a short duration.  MRI (mean recurrence interval) is an important factor in the engineering of fabric structures.  Some tent structures will meet MRI wind speed standards for short events. However, leave that same structure in place over months or years, and at some point it will not hold up as the stress of recurring events takes its toll.

Tension Fabric Structures Built for All Weather Endurance

extruded aluminum used in tension fabric building constructionThe strength of the TFS’s highly-engineered and very strong high grade extruded aluminum frame is reinforced by drawing a heavy and specially formulated 25 oz PVC-coated material with high tensile strength over the frame. The fabric is horizontally tensioned with 10,000 lbs of pressure using a hydraulic ram, stabilizing the structure with the tensile strength created in the process.

The tensioned fabric exerts an inward pull while the horizontal beams keep the arches in a fixed position. This creates more strength and rigidity to the structure while also allowing the fabric to sit above the horizontal beams, an effect that makes snow shed possible. Tent structures do not utilize horizontal tensioning, instead allowing fabric to rest on the purlins, which creates a hang point for snow and prevents it being shed. The curved legs of the TFS also aid in the strength of the building and in the snow shed process, since there is no end eave to stop the snow from sliding like a traditional straight leg structure.

external anchoring system with ballast on tensioned fabric structure

Many tent structures use a generic engineering package that isn’t specific to the intended site or project being sheltered. The engineering of an Allsite tension fabric building will be customized specifically to the project being installed, including factoring in location, duration, local code, occupancy, exposure, etc. For example, the TFS is typically anchored into the structure’s baseplate, partially or fully on the inside of the structure. In contrast, the photo above displays ballast system anchoring, which is used when ground conditions are either too soft or are not able to receive a long stake (utilities, site doesn’t allow any penetration, or ground too hard to drill). Installed with an anchoring system appropriate to the site, the taut, heavy-duty fabric reinforces and locks down the structure, creating an extremely strong and sturdy building able to resist the effects of extreme weather.

Allsite Tension Fabric Structure Helps Rebuild Storm Damaged Town

As reliable, tough and versatile open-span structures, all-weather Allsite structures are a good choice as temporary headquarters in emergency clean up and rebuild situations in areas devastated by storms, earthquake and fire. An Allsite structure was deployed in Joplin, MO after the town was devastated by a tornado in May 2011. Quickly deployed and put in place, the Allsite structure went to work right away to help local officials carry out urgent recovery work, an ideal structure for rapid response operations in community rehabilitation projects in areas stricken by major weather events.

These structures can be safely deployed in any of the growing number of uses and locations with confidence that they will hold up to strong winds and handle any weather situation.

For additional information about Allsite tensioned fabric structures or consulting services, or for a free quote for a fabric structure rental, lease, or sale, please contact Allsite, and speak to one of our experts.

Author Jason Cromwell

Jason Cromwell is the General Manager of Allsite Structure Rentals. He has a degree in Business Economics from the University of California, Santa Barbara. Jason is a 12 year veteran in all matters related to Tension Fabric Structures with Allsite Structure Rentals and has over 20 years of sales, operations, and management experience. Read more about Jason and the rest of our team at https://allsitestructures.com/about/

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