BIZOMAT MAKEOS · Mechanics
Outdoor Cabinet or Machine Wind Tipping and Sliding Check
Will this free-standing cabinet, tank or machine outdoors tip over or slide in the design wind, and if so what anchor tension is needed?
Check of a free-standing outdoor item against wind: dynamic pressure, wind force and its height (as the wind pressure tool), restoring and overturning moments about the leeward edge and the safety factor against tipping, with the anchor tension needed if it falls short (as the machine tipping stability tool), and sliding resistance from friction at the base against the wind force.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Design wind speed | m/s | Design gust or wind speed at the site. |
| Air density | kg/m³ | Air density. |
| Force coefficient | Force coefficient for the shape (about 1.2–1.5 for box shapes). | |
| Area facing the wind | m² | Projected area facing the wind. |
| Height of the area centre | mm | Height above the base of the centre of that area. |
| Item | ||
| Mass (empty if it may be empty) | kg | Mass of the item (use the empty mass if it can stand empty). |
| Height of the centre of gravity | mm | Height of its centre of gravity. |
| Centre of gravity to the leeward tipping edge | mm | Horizontal distance from the centre of gravity to the edge it would tip about. |
| Base friction coefficient | Friction coefficient between the base and the ground. | |
| Required safety factor against tipping | Safety factor against tipping you need. | |
| Anchors on the windward side | Anchors on the windward side that would resist uplift. | |
| Tipping edge to the anchors | mm | Distance from the tipping edge to those anchors. |
| Anchor tension capacity | kN | Tension capacity of each anchor. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Design wind speed
- What it is
- The design wind or gust speed at the site and at the height of the item, from the local wind loading code.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0.000001 m/s to 100 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wind force and overturning moment rise with the square of wind speed.
- Get it right
- Enter metres per second; km/h ÷ 3.6 gives m/s. Use the speed for the site and height, not a weather forecast.
What this means: Air density
- What it is
- The density of the air at the site, used to work out the dynamic wind pressure.
- Units and format
- Enter a number in kg/m³: kilograms per cubic metre. The form accepts 0.5 kg/m³ to 2 kg/m³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.2 kg/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wind force rises in direct proportion to air density.
- Get it right
- Use the value your wind code specifies for design.
What this means: Force coefficient
- What it is
- The force (drag) coefficient for the shape of the item facing the wind, from the wind loading code or shape data.
- Units and format
- Enter a plain number with no unit. The form accepts 0.1 to 5. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.3 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wind force rises in direct proportion to the force coefficient.
- Get it right
- Take it from the wind code for the shape and proportions of the item.
What this means: Area facing the wind
- What it is
- The projected area of the item facing the wind, the width times the height of its silhouette on the windward side.
- Units and format
- Enter a number in m²: square metres. The form accepts 0.000001 m² to 100000 m². Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 m² as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wind force rises in direct proportion to the area.
- Get it right
- Enter square metres; check the widest face, as the wind can come from any direction.
What this means: Height of the area centre
- What it is
- The height above the base of the centre of the wind-facing area, where the wind force is taken to act.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1000 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The overturning moment rises in direct proportion to this height.
- Get it right
- For a plain box it is half the height; measure from the base the item stands on.
Item
What this means: Mass (empty if it may be empty)
- What it is
- The mass of the item that resists tipping and sliding; use the empty mass if it can ever stand empty in wind.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 1000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Restoring moment and sliding resistance rise in direct proportion to the mass.
- Get it right
- Use the lightest condition it can be in, such as empty or during installation.
What this means: Height of the centre of gravity
- What it is
- The height of the item’s centre of gravity above its base, from the maker’s data or a weighing test.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 900 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- This tool takes the restoring moment from mass and the horizontal distance to the tipping edge, so this height does not change the result.
What this means: Centre of gravity to the leeward tipping edge
- What it is
- The horizontal distance from the centre of gravity to the leeward edge of the base, about which the item would tip.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The restoring moment and tipping factor rise in direct proportion to this distance.
- Get it right
- Measure to the edge of the feet or base frame, not the cabinet skin, on the side away from the wind.
What this means: Base friction coefficient
- What it is
- The friction coefficient between the item’s base and the surface it stands on, from tests or friction data for the materials.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 2. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.3 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Sliding resistance rises in direct proportion to the friction coefficient.
- Get it right
- Use a value for wet conditions if the site can be wet.
What this means: Required safety factor against tipping
- What it is
- The safety factor against tipping that your design code or company rule requires, compared with restoring ÷ overturning moment.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 5. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.5 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Take it from the code that applies to the installation.
What this means: Anchors on the windward side
- What it is
- The number of anchors on the windward side that would hold the item down against tipping.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 100. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The tension needed per anchor falls in inverse proportion to their number.
- Get it right
- Count only anchors on the windward side; 0 means none are fitted.
What this means: Tipping edge to the anchors
- What it is
- The horizontal distance from the leeward tipping edge to the line of the windward anchors.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 600 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A longer lever lowers the tension needed in each anchor.
- Get it right
- Measure from the tipping edge, not from the centre of gravity.
What this means: Anchor tension capacity
- What it is
- The tension capacity of one anchor in the base or foundation, from the anchor maker’s data or design.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts 0 kN to 100000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter kilonewtons per anchor, and check the base or slab the anchor is set in as well.
Method and formulas
- q = ½ ρ V²; wind force F = C_d q A at the area centre height (as the wind pressure tool).
- Restoring moment = W b; overturning moment = F h; factor = restoring ÷ overturning; anchor tension = (factor needed × overturning − restoring) ÷ (anchors × lever) (as the machine tipping stability tool).
- Sliding resistance = μ W, against F.
- Example: 15 m/s gives 351 N of wind; the tipping factor is 2.5145 and friction resists 882.6 N.
Limitations
- Steady wind with one force coefficient; gusts, vortex shedding and shielding are not covered.
- Rigid item on a level base; soft ground can let it rock.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check an outdoor switchboard or cabinet
- Decide whether a temporary tank or machine needs anchors
- Find anchor tension for a wind rating
Who it is for
- Site engineers
- Electrical contractors
- Maintenance engineers
What you get
- Wind pressure, force and overturning moment
- Tipping safety factor and anchor tension
- Sliding resistance
Interpreting the result
- An empty tank or cabinet is the worst case: always check with the lightest mass it can have outdoors.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3028, 167–168. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Roof loads, fixings and wind
In Rooftop Solar for Factories by the Numbers
What it covers: How to estimate the dead load of an array, the wind pressure and uplift on flush-mounted and ballasted modules, the loads on clamps and brackets, and the wind risk to modules during installation.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Outdoor Cabinet or Machine Wind Tipping and Sliding Check calculator