The load capacity of scaffolding is calculated by dividing the scaffold weight capacity by the sum of the maximum intended load and the weight of the scaffold. Being able to calculate the load capacity of scaffolding is crucial because it helps you avoid overloading the scaffold. Here’s the formula used to calculate the live load and other things you need to consider.
The formula for calculating the scaffold load capacity is as follows:
Load Capacity = (Scaffold Weight Capacity) / (Maximum Intended Load + Weight of Scaffold)
- Scaffold Weight Capacity refers to the maximum load that the scaffold can hold. This is determined by the manufacturer and it’s marked on the scaffold.
- Maximum Intended Load is the total weight of tools, workers, and materials that will be placed on the scaffold at any one time.
- The weight of the scaffold is the weight of all the scaffold components. This includes the platform, frames, cross braces, guardrails, and any tools or materials that will be placed on the scaffold.
Factors to consider when determining the scaffold load capacity
There are several things to consider when determining the load capacity of a scaffold and one of them is the load capacity rating as specified by the manufacturer. Usually, the weight of the scaffold plus the maximum intended load is lower than the rated capacity. The manufacturer should clearly indicate the load capacity rating on the scaffold.
Secondly, you should also consider the maximum intended load. This is basically the total weight of the tools, workers and materials that are to be placed on the scaffold at any one time.
The weight of the scaffold is another crucial factor that needs to be considered. Here the weight includes that of the scaffolding components and any materials or tools placed on the scaffold.
How level the ground is, is another crucial thing to consider because it can significantly impact the load capacity of scaffolding. Other factors you should account for when determining the safe working load for scaffolding include the speed of the wind and seismic activity ( probably not relevant in UK ).
How to calculate the safe working load of scaffolding
When calculating the safe working load( SWL) you should consider the scaffold weight capacity, maximum intended load, scaffold weight and the safety factor. In the UK, a safety factor of at least 2 is applied to the scaffold load capacity to ensure that it can safely support any intended load. This means that the maximum load that scaffolding supports shouldn’t be more than half its load capacity.
The formula for calculating the SWL is as follows:
SWL = (Scaffold Weight Capacity) / (Maximum Intended Load + Weight of Scaffold) x Safety Factor
- Scaffold Weight Capacity is the maximum load that the scaffold can hold, as specified by the manufacturer and marked on the scaffold.
- Maximum Intended Load is the total weight of workers, tools, and materials placed on the scaffold at any one time.
- Weight of Scaffold is the weight of all the scaffold components and any tools or materials that will be placed on the scaffold.
- Safety Factor is a factor that accounts for the uncertainties in the load. The safety factor in the UK is typically 2.0, although it may vary depending on the specific conditions and regulations.
How to calculate the live load of scaffolding
The live load of scaffolding, commonly known as the uniformly distributed load ( UDL ) is calculated using this formula:
UDL= ( Weight of all materials, tools & equipment and personnel on scaffolding) / (Total area of scaffold decking)
If you have the total weight of materials, personnel, tools & equipment on scaffolding as 1200 kg, and the scaffold decking total area is 40m2, here’s how you’ll calculate the live load;
UDL= 1200 kg/ 40 m2
Therefore, UDL=30 kg/m2 or 30 N/m2
When calculating the UDL, you should take into consideration any imposed loads like snow, wind, etc. This way, you’ll get a more accurate figure.
How to calculate the dead weight of a scaffold
The formula for calculating the dead load ( DL ) of scaffolding is the same as the formula for calculating the dead weight of a scaffold. The formula can be expressed as:
DL = Wp + Ws + Wb + Wg + Wa
- Wp is the weight of the platform or working surface of the scaffold
- Ws is the weight of the scaffold structure or frames
- Wb is the weight of the scaffold braces or cross bracing
- Wg is the weight of the scaffold guardrails
- Wa is the weight of any other permanently attached components or tools.
To calculate a dead load of scaffolding, the weight of each component should be determined and added up to obtain the total dead load. It is crucial to ensure that the dead load is within the load capacity of the scaffolding and any supporting structures.
When working with a qualified and competent person, you’ll easily ensure that you don’t put anyone at risk by overloading your scaffold. With the different formulas above, you can easily ensure that you’re adhering to the safety requirements and the Work At Height Regulations when it comes to scaffolding load capacity.