Updated: Mar 31, 2022
In properly regulated jurisdictions, even a temporary tensile structure such as event temporary tents that aren’t considered to last long life (i.e 3 to 6 months) and not important shall typically withstand wind speeds of 45-75 km per hour (KPH). These structures don’t stand a chance against 100 KPH wind gusts, let alone heavy rains. A properly engineered permanent wind load rated structure shall withstand heavy rainfall and wind loads up to 160 to 200 KPH depends on the location’s conditions, applicable codes of practice and regulations. That’s the most important difference between the two. Be wary when temporary life exceeded few months such as 2 or 3 years, in such situations the wind codes has their calculations of proper design wind load based on return period of high winds probability which may go higher and laid slightly below permanent structure (i.e. in some areas even a 3 years life camp shall be designed to withstand 140 KPH versus permanent of 160 KPH, not so far) therefore, be cautious when temporary tensile structure is needed for several years not months.
What must be taken into consideration in
designing wind rated tensile structures:
Tensile fabric structure is engineered to withstand a stated wind speed, which involves three types of wind load forces: shear, lateral, and uplift.
Shear load – horizontal wind pressure that can make a facility tilt
Lateral load – push-pull pressure that can move a structure off its foundation
Uplift load—pressure from wind flow that causes lifting effects
But the wind force itself is only one part of the equation. So, what exactly makes a structure that can stand up to the elements and weather conditions in any location? The answer lies in engineering and fixation details power.
Fixation details power in fabric structures:
Tensile fabric structure is more than the sum of its parts. Even when built with tough, durable fabric, the way that fabric is attached to a frame is ultimately the most important aspect in determining a structure’s efficacy, productivity, profitability, and the safety depend on structures that stand up to the most unpredictable conditions. Custom engineering is key to setting up a facility that will meet the specific needs of your job.
The idea is to fix a tensile structure with enough power to withstand the opposing forces of wind, both vertically and laterally in a way typical design process, one of the first things you shall do is to run the model simulation to determine the fixations forces required for each load case, which includes dead load, snow load, and as much as required of variations on wind load depending on the direction the wind comes. Hence, with so many factors affecting the wind forces imposed on a structure — altitude, proximity to bodies of water, structure size, roof slope, structure shape and more — it’s critical that you take all that into consideration.
Tensile structure planning checklist:
when you plan a tensile structure, mind the below check list:
- Select an experienced contractor with previously executed wind rated tensile structure projects with similar complexity in the last 5 to 10 years.
- Select a contractor who shows familiarity with your region meteorological data and codes of practice? Did that contractor undertake previous jobs within your region in the last 5 to 10 years? Visit one of them.
- Select a contractor who is using competent structural design engineer with particular focus on analyzing wind loads and other loads on tensile fabric structures?
- Ask your designer whether the shape of your structure can be handled using typical codes of practices or needs extra testing (i.e wind tunnel test)
- Pay high attention on the cost of maintenance and warranty of fabric. Tensile fabric is delicate material and although it has tremendously high tensile capacity, but a car key can scratch it and since they are in continuous state of tension and vibration over the years then they must undergo-after completion- a properly made custom periodic preventive maintenance regime. Never underestimate the importance of periodic maintenance of any tensile structure. It is immensely important, and its absence badly impacts your tensile structure expected service life.
- Make sure that the falling or flying objects risk is assessed. Tensile fabric cannot take any impact from falling or flying objects during wind events or without. Make risk assessment and if risk is high then perhaps fabric structure is not the right choice for that development. Be vigilant when your structure is in typhoon or tornado prone regions.
Finally, tensile fabric structures when made properly proved unprecedented resilience against weather conditions and have already offered super feasible solutions for big spans structures such as stadiums and big arenas. The technology itself is evolving since thousands of years started with Arabian and Eskimo tents and ends with contemporary stadiums roofs and shopping malls etc. Its indeed inherited part of human culture and basic needs since ever.
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Wish you all the best,