Tower Wind Load Calculator

Input data

Formula used

This calculator uses a common wind-pressure workflow for preliminary tower checks:

• Height coefficient: Kz = 2.01 × (z/zg)^(2/α), using exposure-dependent α and zg.
• Velocity pressure: qz = 0.613 × Kz × Kzt × Kd × I × V² (SI; qz in Pa, V in m/s).
• Design pressure: p = qz × G × Cf.
• Wind force: F = p × A.
• Overturning moment: M ≈ F × (H/2) assuming a mid-height resultant.

How to use this calculator

1. Enter the basic wind speed from your project criteria or local map.
2. Select exposure category matching surrounding terrain and roughness.
3. Input tower height and projected area normal to the wind direction.
4. Confirm the gust factor and force coefficient, then apply importance and site factors.
5. Press Calculate to view pressure, force, and overturning estimates.
6. Use Download CSV or Download PDF for records and reviews.

Example data table

Example values are illustrative. Your project criteria may differ.

Tower wind loading in construction planning

Temporary towers and permanent masts face wind demand during erection, lift operations, and commissioning. This calculator turns site wind speed, terrain exposure, and geometry into working values for velocity pressure, design pressure, wind force, and a simplified base moment. The outputs help teams screen options, compare tower types, and document assumptions before detailed analysis.

1) Inputs that drive wind force

Wind pressure grows with the square of wind speed (V²). A 20% increase in wind speed raises pressure by about 44%. For example, 40 m/s and 48 m/s are not “close”; they produce noticeably different demands. Projected area should represent the silhouette normal to wind, including platforms, ladders, cable trays, and appurtenances.

2) Exposure category and height coefficient

Exposure reflects terrain roughness and strongly affects the height coefficient (Kz). Open terrain (Exposure C) generally produces higher pressures than suburban surroundings (Exposure B), especially as height increases. The calculator estimates Kz from height and exposure using an industry-style power law, providing practical values for early-stage comparison.

3) From pressure to force and overturning moment

Design pressure p is computed from velocity pressure qz with gust and force coefficients. The force is F = p × A. As a quick check, if p ≈ 2.5 kPa and A = 18 m², then F ≈ 45 kN. With a 40 m tower and a mid-height resultant, a base moment of roughly 900 kN·m is expected.

4) Coefficients, conservatism, and documentation

Gust factor (G), directionality (Kd), topographic factor (Kzt), and importance (I) influence demand and should match your governing wind standard or client criteria. Force coefficient (Cf) is especially sensitive for lattice versus solid systems; use vendor data or code tables when available. Exporting CSV and PDF provides traceable records for reviews, bids, and safety files.

FAQs

1) What is “projected area” for a tower?

Projected area is the tower’s silhouette normal to the wind direction. Include major members plus attachments such as ladders, platforms, signs, antennas, and cable trays to avoid underestimating wind force.

2) Which wind speed should I enter?

Use the project’s specified basic wind speed from the applicable wind map or client requirement. If your standard uses a particular gust duration, enter the equivalent speed in m/s, km/h, or mph.

3) How do I choose Exposure B, C, or D?

Exposure B suits urban/suburban terrain with many obstructions. Exposure C matches open terrain with scattered obstacles. Exposure D is for coastal or very flat areas with long fetch. When unsure, select the more conservative exposure.

4) When should I override the force coefficient (Cf)?

Override Cf when you have tower-specific data, code-based coefficients, or a known solidity ratio. Lattice towers can vary widely; using a generic value may be too conservative or too light for your configuration.

5) Should I include temporary construction items?

Yes. Add temporary items that catch wind, such as hoists, lifting frames, tarps, temporary platforms, or stored materials. For staged construction, run multiple cases to capture worst credible configurations.

6) Is the overturning moment exact?

No. The moment is a screening estimate assuming the resultant force acts at mid-height. Real towers require distributed-load analysis and code load combinations. Use the moment for early comparison, not final design.

7) What do the CSV and PDF downloads include?

They include your last calculated inputs, computed coefficients, pressures, force, and moment. Use CSV for spreadsheets and QA checks, and PDF for submittals, review packages, and site documentation.