The Engineering feature allows you to perform structural calculations of your scaffold right inside the app with just a few extra clicks. Design, plan, and calculate all in one place.

Table of contents

• Intended use
• Recommended approach
• Important limitations
• Further details
• Step-by-step guide
• 1. Enter Engineering mode
• 2. Calculation settings
• 3. Calculate
• 4. View results
• 5. Create a new calculation
• Stabilizing a scaffold
• In brief
• Purpose of different stabilizing components
• When is the scaffold stable?
• Error / warning messages
• Failed calculation
• Warnings alongside results
• Load increase due to sway
• Lift of base plate
• Slip risk
• Bending moment in standards
• Terminology Translations

Intended use

The Engineering tool is intended to be used together with the manufacturer’s technical documentation. With the Engineering feature in Scaffcalc, you can evaluate the stability of your scaffold and visualize how the scaffold behaves under load, including deformations as well as forces in components, ground supports, and anchor supports. Use these results alongside the manufacturer’s documentation to assess your scaffold design.

This is the first version of the Engineering tool. It has limitations that will be addressed in future versions. The intended use of the final version is to rely fully on the Engineering tool alone.

Recommended approach

The following describes the recommended methodology for interpreting the results. To learn how to use the feature to calculate results, follow this step-by-step guide.

For each new scaffold calculation, start by checking the displacements. Displacements show how much the scaffold moves under the applied loads. If the scaffold moves significantly in any direction, consider improving the stability of the scaffold. As a rule of thumb, use H/120. That is, for any two points on a standard with a height difference H, the relative horizontal displacement between those points should be no more than H/120. Next, look for any error/ warning messages. These highlight important scaffold behavior: either errors that prevent the calculation from running, or warnings about results that should be reviewed before proceeding. Click here to read more about specific error and warning messages.

Once the scaffold is well designed based on the displacements and error/warning messages, you can check the forces on the elements and supports against the manufacturer’s documentation to verify they are within the allowed limits. Important note: The forces shown in Scaffcalc are dimensioning forces, which means they include safety factors. They should be compared with the manufacturer’s design capacities (look for Rd subscripts). If the manufacturer states permissible loads or forces, multiply those values by 1.5 to compare with the forces shown in Scaffcalc. The unit of forces in Scaffcalc is kN.

Important limitations

The current version of the Engineering tool has limitations that will be handled in future updates to the feature. Some limitations will affect the resulting behavior of the scaffold.

The most important limitations are:

• Facade and freestanding structures only

Suspended scaffolds and scaffolds not covered by EN 12811 are currently not considered in the scope of the Engineering feature. EN 12811 excludes the following:

1. Platforms suspended by ropes
2. Horizontally movable platforms
3. Powered-operated scaffolds
4. Scaffolds used as protection for roof work
5. Temporary roofs
• No structural verifications

Structural verification, including a calculation report, will be addressed in future versions of the Engineering feature. With the current feature, results must be verified against manufacturers’ tables.

• Layher Allround scaffolds only

The feature currently only supports Layher scaffolds. More specifically, Layher Allround LW.

• Anchored ground supports

All ground supports are modelled as fully anchored to the ground, meaning that instead of lifting when exposed to heavy wind, they will not move but instead display a tension force in the ground support. You can mitigate this by either taking care of the forces (by using counterweights/ground anchors) or by changing the scaffold design (widening of the base, for example). Modeling of counterweights will also be possible in future versions.

• Default friction coefficient

The friction coefficient for the base plates on the ground is set to a default of 0.5. This means the results assume the base plates start slipping if the horizontal force exceeds 50% of the simultaneous vertical compression force in the base plate.

• Connections: constant stiffness and no eccentricity

This first Engineering version models connection stiffness as constant, independent of the applied force. Also, there is currently no eccentricity applied to the connections.

• No reduction in regard to facade opening ratio

In the first version of Engineering, the permitted wind load reduction is not considered when an unclad scaffold is mounted close to a facade with few or no openings. Future versions will let the user select facades and specify the facade opening ratio to be considered in the calculation.

• No dynamic loads

Dynamic loads are not currently available for calculations. Results are based on static load cases only. According to EN 12811, dynamic loads should be considered for any moving item on the scaffold, apart from people.

• No specialized load on bird cage scaffolds

The vertical platform load is uniformly distributed in each bay on all scaffolds. The EN 12811 note that the load on bird cage scaffolds should be applied over a maximum surface area of 6 square meters (with a reduced imposed load on surrounding areas) is not considered.

• Stair components don’t provide stability bracing.

Further details

If you are interested in the details of the Engineering 1.0 Tool, please read the technical documentation:

Step-by-step guide

Follow the steps below to calculate the forces on your scaffold and view the results.

1. Enter Engineering mode

Once you’ve built a scaffold you wish to calculate the forces on, exit Build mode and enter Engineering mode using the switch at the top right:

In Build mode, you can build and edit your scaffold.

In Engineering mode, you can calculate and view the forces on the scaffold.

You can easily switch between Build and Engineering mode at any time; all edits are saved.

2. Calculation settings

Next, enter the calculation settings specific to your scaffold project. These determine the loads applied to the scaffold. To learn more about each setting, click the arrow beside it below.

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Reference wind speed

One option is to choose indoor: no wind.

For outdoor, select reference wind speed based on the location.

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Terrain type

Choose the terrain type that best matches the project site from the list below. If you’re unsure, choose the lower option.

3. Calculate

Once you’re happy with your settings, press Run Calculation. The app applies the loads based on your inputs and evaluates all relevant load scenarios. Press Abort calculation if you wish to cancel the calculation before it is finished.

4. View results

Once the calculation is finished, the results will be saved in the list under Calculation Results. Each result corresponds to an individual (unconnected) scaffold. Select a scaffold in the drop-down list to view its results.

The first result in the list is selected by default, and that scaffold’s displacement is displayed. You can return to this list at any time to switch between results.

After selecting the result you want to view, toggle the different results below.

If any error/ warning messages appear for the calculation, read about it here.

Selected Result Settings

Click on the arrow to display which calculation settings the currently selected result is calculated with. Double check that your calculation settings are correct, if not, create a new calculation.

Displacements

The displacements are automatically visible when selecting a result to view. The displacement visualises the movements of the scaffold for the single worst case load scenario. You can hide the scaffold, in the list to the very left, if you wish to display the displacement shape only. To see the displacement values, zoom in on the displacement shape.

Force results: Compression/Tension

Forces on the scaffold are grouped into compression and tension. When Compression is selected, only the greatest compression force (negative force) occurring per component / support is displayed. When Tension is selected, only the greatest tension force (positive force) per component/ support is displayed.

Note that because the maximum value per element is shown, the forces visualized may not occur simultaneously. For a component/supporting element with no tension force in any load combination, nothing is displayed when Tension is selected, and vice versa.

Moment forces and shear forces can also be viewed as sub-options of component forces. For these, Compression refers to the maximum negative moment/shear force, and Tension refers to the maximum positive moment/shear force.

• Component Forces

Shows, for each element, the greatest forces it is subjected to: normal forces (along the element), bending moments and shear forces. Switch between the different force types in the drop-down list.

Adjust the scale factor to change the size of the force visualisation.

Use the selection filter to filter out component types for easier visualisation.

• Ground Forces

Displays pressure/tension force from each standard on the ground.

Set the maximum allowed force value to display forces exceeding this limit in red. Values are set separately for compression and tension forces.

Adjust the scale factor to change the size of the arrows.

• Anchor Forces

Displays pressure/tension force from each anchor on the facade.

Set the maximum allowed force value to display forces exceeding this limit in red. Values are set separately for compression and tension forces.

Adjust the scale factor to change the size of the arrows.

• Beam Spigot Forces

Displays the force acting from a beam spigot onto a ledger / lattice beam.

Set the maximum allowed force value to display forces exceeding this limit in red. Values are set separately for compression and tension forces.

Adjust the scale factor to change the size of the arrows.

5. Create a new calculation

It is easy to go back and edit the scaffold or calculation settings to try a different alternative. In the list of results, click + create new calculation. This returns you to the calculation settings, which you can edit and then click Run Calculation again.

If you also wish to edit the model, then after clicking + create new calculation click on Build above to exit Engineering mode and go back to Build mode. Now you can edit the scaffold and retrace the steps to calculate the new forces.

Note: By editing the scaffold, all calculation results will be deleted. A warning modal will appear to prevent you from accidentally deleting calculation results.

Stabilizing a scaffold

Stabilizing a scaffold means ensuring it can carry horizontal loads (wind) and that the standards are laterally supported along their height. What’s required depends on the loads applied to the scaffold. The following describes best practices, the purpose of different bracing elements, and important don’ts.

In brief

• Use diagonal braces and ledgers to provide horizontal stability for each standard at 2 m intervals.
• Use facade anchors (including V-anchors) whenever possible.
• Don’t connect a facade anchor or diagonal brace more than 200 mm from a lift level (i.e., where there are horizontal members) to reduce the risk of bending the standard.
• Use the standard row principle: Ensure every row of standards is braced against horizontal loads (wind) using either V-anchors or diagonal braces at every 5th bay (and end bays). A non-braced row of standards can be braced by connecting it with decks / horizontal diagonals to a braced row of standards.
• Add horizontal diagonals when the stability provided by decks is not enough (typically useful for larger loading bays).

Purpose of different stabilizing components

• Facade anchoring

Anchoring a scaffold to a facade is best practice for stability. Facade anchors should be placed no more than 200 mm below or above a lift level (i.e., close to a horizontal member), otherwise the standard may bend. V-anchors should be placed at least at every 5th standard along the facade. In Scaffcalc, anchors carry axial forces only. Therefore, V-anchors must be modeled to carry wind acting parallel to the facade, as long as the scaffold is not freestanding.

Don’t skip V-anchors or place an anchor in the middle of a standard without reinforcing that standard.

• Diagonal braces

Diagonal braces help the scaffold resist horizontal loads (wind) by creating a stiff, triangulated system. They can be used in several ways:

1. To compensate for limited facade anchoring If the scaffold partially or fully lacks facade anchors, diagonals can transfer horizontal loads through the scaffold structure.
2. To brace a standard Standards should be laterally supported at 2 m intervals. If anchors are only placed every 4 m, use diagonal braces to brace the standard between anchor points.
3. To stabilize facade scaffolds along the facade Diagonals also brace the scaffold along the facade (perpendicular to the direction of the anchors).

Pro tip: The most efficient way to use diagonals is to connect them in continuous lines:



Don’t connect diagonals to a point on a standard unless that point is also connected to a ledger, anchor, or another diagonal in a way that braces the standard against bending.

• Horizontal diagonal braces (or decks)

Horizontal diagonal braces connect an unstabilized row of standards (i.e., with no anchor or vertical diagonal brace) to an adjacent stabilized row. Connect the rows with planks/decks or horizontal diagonal braces at every lift level, approximately every 5th bay and end bays.

Note: Decks provide similar stability to horizontal diagonals but are much less rigid. Opt for horizontal diagonal braces below/instead of decks when horizontal displacement of the scaffold is large, or when you wish to transfer forces from diagonal braces to facade anchors instead (typically for larger, single loading decks).

When is the scaffold stable?

A scaffold is stable when all of the following criteria are met:

• Horizontal displacement is small. As a rule of thumb, use H/120 — for any two points on a standard with a height difference H, the relative horizontal displacement between those points should be no more than H/120.
• No significant load increase due to sway. The additional horizontal load from sway effects is zero or small. If zero, the warning disappears.
• No lift or slip in any base plate. No base plate is subjected to tension (lift), and no base plate has a horizontal force exceeding 50% of the simultaneous vertical compression force (slip risk). When resolved, the slip and lift warnings disappear.
• All components can carry the forces they are subjected to. The forces on all elements and supports are within the limits stated in the manufacturer's documentation. This includes the standards, ledgers, connections and diagonal braces, as well as the supporting structures — ground supports (base plates) and anchor supports (facade anchors) — which must be verified against the manufacturer's stated design capacities for compression, tension, and shear.

Error / warning messages

Failed calculation

If a calculation fails, an error message will be displayed with the reason for the failure. Some alternatives of this error message are:

• Supplier not supported Only Layher Allround is currently available for calculations
• Attached with a ‘VIEW’ button If the error message includes a view button, the calculation found an error in the model that would cause the calculation to fail. Click the button to zoom to the error(s).
• Unstable scaffold If this is displayed, the scaffold is too vulnerable to lateral movement. A displacement shape will be visible to help you understand which direction is most unstable. Improve stability by stabilizing the scaffold.
• Unknown

If the error message simply states that the cause is unknown, try again. If the issue persists, please contact support.

Warnings alongside results

There are some warnings that can appear alongside the finished result to make you aware of some critical points in the scaffold.

Load increase due to sway

If the scaffold is vulnerable to horizontal movement due to the vertical loads applied in any load combination, the horizontal load in that load combination will be increased by a percentage (noted in the warning) to account for the sway effect. To avoid this load increase, try stabilizing the scaffold.

Lift of base plate

Lift of base plate means the base plate wants to lift off the ground. In Ground Forces (Tension mode), you can see the tension force required to keep the base plate in contact with the ground. If this is not addressed, it can lead to scaffold overturning. Reduce the lift by stabilizing the scaffold, or resist it by anchoring the base plate to the ground or adding counterweights. Click View in the warning to display the required counterweight for each node.

Slip risk

Slip risk in any base plate means that, in some load scenario, the horizontal force in the base plate is greater than 50% of the simultaneous vertical force. This could cause the base plate to slip or slide horizontally.

To solve this, first add any missing ledgers at the base of the scaffold. Next, try to stabilize the scaffold further and check for missing V-anchors.

If this cannot be solved by improving stability, anchoring the components to the ground or adding counterweights to the scaffold is the best solution. To calculate the necessary counterweight, the maximum ratio Horizontal Force (H) / Vertical Force (V) is displayed per base plate. The necessary added weight can be calculated as 2 x H - V (without any negative signs). Example: H = 4 kN, V = -4 kN. Counterweight = 2*4 - 4 = 4 kN.

Bending moment in standards

Standard components are designed to primarily carry vertical loads and should not carry any of the horizontal loads applied to the scaffold. Horizontal forces should instead be carried mainly via diagonals and facade anchoring. Bending moments in standards should be considered when assessing the capacity of the standards. Scaffcalc currently warns the user when bending moments make the recommended standard capacities in the RISE Typkontrollintyg 154801 obsolete.

Terminology Translations