Pole and Wind Inputs
Choose a unit system first. Values are converted internally before calculation.
Example Data Table
Examples demonstrate input structure only. They are not approved design cases.
| Example use | Wind speed | Height | Base / top diameter | Exposure | Suggested strips |
|---|---|---|---|---|---|
| Short site marker pole | 90 mph | 20 ft | 14 in / 8 in | B | 30 |
| Utility distribution pole | 115 mph | 35 ft | 18 in / 8 in | C | 40 |
| Open-site lighting pole | 130 mph | 50 ft | 24 in / 10 in | C | 60 |
| Coastal exposed pole | 145 mph | 60 ft | 28 in / 12 in | D | 80 |
Concrete Pole Wind Load Basics
Wind acting across a concrete pole produces lateral pressure. That pressure grows with wind speed and generally increases with elevation. A tall pole therefore develops horizontal force and a larger overturning demand at grade. Taper matters because projected width changes from the base to the top.
This calculator treats the exposed shaft as a linearly tapered circular member. It divides the height into narrow horizontal strips. Each strip receives a wind pressure based on its elevation, projected width, gust factor, force coefficient, and selected adjustments. The strip forces are added to obtain total base shear. Each strip force is also multiplied by its height to obtain base moment.
Use actual pole dimensions above finished grade. Include only the bare shaft in this model. A bracket, light fixture, sign panel, transformer, cable, or attached equipment can add substantial projected area. Analyze those items separately, then combine their force and moment with the shaft result.
Formula Used
The velocity pressure model is evaluated at each strip elevation. It uses an exposure coefficient that changes with height. The equations are:
qz = 0.00256 × Kz × Kzt × Kd × V² × A
p = qz × G × Cf × S
dF = p × D(z) × dz
Mbase = Σ(dF × z)
Here, V is wind speed in mph, A is the additional wind factor, S is the shielding factor, and D(z) is pole diameter in feet. It derives factored values for review by multiplying service force and moment by the selected load factor.
How to Use This Calculator
- Choose Imperial or Metric inputs before entering values.
- Enter the governing wind speed and exposed pole height.
- Enter base and top outside diameters for the visible shaft.
- Select terrain exposure and verify all project-specific factors.
- Set the force coefficient and load factor from your governing method.
- Calculate, then review base shear, moment, pressure, and resultant height.
Interpreting Results
Base shear is the lateral load transferred toward the foundation system. Base moment is usually the key value for checking pole reinforcement, embedment, foundation geometry, soil reactions, and connections. The resultant height shows where a single equivalent force would act to create the same calculated moment. It is useful when combining shaft loads with other wind-loaded equipment.
Use qualified engineers for final pole design and approval.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates wind pressure, projected shaft area, horizontal force, base shear, and overturning moment for a tapered concrete pole above grade.
2. Is this a final engineering design?
No. It is a preliminary calculation tool. Final design must use the governing code, approved wind maps, complete geometry, site conditions, and licensed engineering review.
3. Which wind speed should I enter?
Enter the basic wind speed required by the governing jurisdiction and design standard. Do not substitute a weather forecast or a casual local estimate.
4. Does the model include pole taper?
Yes. Diameter changes linearly between the entered base and top values. The calculation evaluates each strip using its own projected width.
5. What does terrain exposure change?
Exposure changes the height-dependent pressure coefficient. Open terrain generally develops higher pressure at a given height than sheltered urban or wooded terrain.
6. What is the topographic factor?
The topographic factor accounts for wind speed-up over features such as hills, ridges, and escarpments. Use 1.00 only when the applicable procedure permits it.
7. Why is base moment important?
Base moment combines wind force with its height above grade. It governs many checks for pole bending, reinforcement, embedment, foundation capacity, and overturning resistance.
8. Are luminaires, signs, and wires included?
No. The result covers the bare tapered shaft only. Model each attachment, conductor, sign, or fixture separately and add their force and moment effects.
9. Can I use results for foundation sizing?
They can inform preliminary foundation checks. Foundation design also needs soil properties, embedment, geometry, reinforcement, groundwater, uplift, and the governing load combinations.
10. How does the load factor work?
The calculator first reports service force and moment. It then multiplies both by the load factor to show factored values. Use the factor required by your selected design approach.
11. Can I enter metric values?
Yes. Select Metric before calculation, then enter wind speed in km/h, height in metres, and diameters in millimetres. Results display in both unit systems.