Scaffold systems are subjected to the same winds as the building to which they are attached. That means safety and compliance with various regulations hinges on scaffolding engineers being able to correctly calculate wind loads and design an appropriate system.
Many different factors need to be considered when making these calculations, including:
The wind has a tendency not only to blow but can suck outwards as well. Just one 90mph wind gust is enough to cause significant damage to the scaffolding and possibly the building it’s installed on if the scaffolding is not properly designed and engineered. With so many variables to consider, “winging it” just isn’t an option.
Read on to learn more about the considerations for engineering scaffolding to compensate for gusting and wind loads.
Codes such as the International Building Code provide specific criteria for determining the equivalent uniform wind pressures at any point on the building or scaffold. In addition to the general OSHA regulations for scaffolding, there may be other region-specific codes you’ll need to adhere to, such as ASCE-7 or the Eurocode.
Scaffolding engineers must also consider the OSHA wind speed limit for working at height. OSHA 1926.1431(k)(8)(i) states:
Wind. When wind speed (sustained or gusts) exceeds 20 mph at the personnel platform, a qualified person must determine if, in light of the wind conditions, it is not safe to lift personnel. If it is not, the lifting operation must not begin (or, if already in progress, must be terminated).
Scaffold systems are subjected to the same wind forces as the building to which it is attached. This means that any applicable wind, seismic, or other loads required by the local building code also apply to the scaffold design.
The scaffold system must be robust enough to handle the higher loads for high-wind zones. This may involve providing more mechanical ties, increased buttress scaffolds, or other means such as counterweights or cabling.
Non-permanent structures such as scaffolding can often benefit from wind reduction factors based on the longevity of the scaffold in place.
This can effectively reduce the amount of wind pressure the engineer needs to consider. The effects of gusting are also considered in the building code load calculation.
Wind forces must be applied in three directions: in/out of the facade (pressure/suction), parallel to the building, and up/down. The Scaffold Engineer must resolve all the forces into connections and/or develop adequate dead load resistance to prevent scaffold overturning or collapse.
As the complexity of the scaffold design increases, so can the cost. However, just because a scaffold may be located in a high-wind area does not necessarily equate to increased prices. This could be a simple matter of added mechanical anchors, which are relatively inexpensive compared to the overall budget.
If your project requires scrim or debris netting, it is critical to understand that this will dramatically increase the wind pressures on the scaffold and its connections. The net essentially creates a huge “wind sail” which collects the wind forces and must be resolved somehow.
If cost is a consideration, consider omitting the netting for scaffolds in high-wind areas. This can reduce the effective wind force up to 75% or more when compared to just a bare scaffold without a net. Also, when subjected to high wind gusting, the netting itself can tear and require replacement.
The Steven F. Udvar-Hazy Center in Chantilly, Virginia, is an aviation museum that contains historically significant planes and spacecraft, such as the Concorde Jet and Space Shuttle Discovery. The aging roof membrane required repairs, and the contractor chose Scaffolding Solutions to provide the scaffolding.
Due to the curved shape of the enormous hangar and location in an open field with no other wind protection, gusting or sustained winds could cause lateral force issues on the scaffolding. Scaffolding Solutions adapted the OCTO scaffolding system and safety locking features innovatively and engineered customized lateral supports.
The end result was a strong scaffold that matched the curvature of the building while mitigating the dangers of high wind loads and gusting. The general contractor was so pleased with the results that they asked Scaffolding Solutions to engineer and install interior overhead protection for visitors to the museum.
Correctly calculating wind loads for a scaffolding system is paramount to ensuring safety and compliance with various regulations. At Scaffolding Solutions, we have decades of experience and countless unique projects under our tool belts. Contact one of our team members below to learn more about how we can help solve your scaffolding challenges.
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