Enter wind, exposure, coefficients, and dimensions. The tool builds a pressure envelope, estimates zone forces, and reports an approximate base overturning moment.
The equations below follow a velocity-pressure approach commonly used by major standards.
- Select your preferred display units.
- Enter wind speed, exposure, and reference height.
- Set Kzt, Kd, I, and gust factor G.
- Choose a surface and enclosure condition.
- Enter height and width for face area.
- Optional: set custom tributary area and zones.
- Click Calculate and review envelopes and forces.
- Export CSV or PDF for coordination and reviews.
These examples are computed using the same formulas in this file. Use them as a reference for typical inputs and the direction of results.
| Scenario | V | H | Exposure | Cp | |GCpi| | p+ (Pa) | p− (Pa) | Total force (kN) |
|---|---|---|---|---|---|---|---|---|
| Office tower, coastal exposure | 45 ms | 160 m | D | 0.80 | 0.18 | 1,780 Pa | 1,126 Pa | 7,095 kN |
| Residential tower, urban exposure | 40 ms | 120 m | B | 0.80 | 0.18 | 1,015 Pa | 642 Pa | 2,223 kN |
| Podium + tower, partially enclosed | 50 ms | 200 m | C | -0.50 | 0.55 | 128 Pa | -2,689 Pa | -16,587 kN |
Selecting governing wind speed and terrain
High rise loads start with the governing basic wind speed from your adopted code map. Exposure category changes the height profile through Kz. Urban terrain lowers pressures near the ground, while coastal exposure increases Kz and boosts design pressure at upper elevations.
For quick QA, compare qz at the reference height against a hand check using the same speed and factors. A 10% increase in speed raises pressure by about 21% because V is squared. Use custom tributary area for panel checks, and keep zone areas consistent with your load path. Record chosen Cp and GCpi values so later revisions remain traceable across packages.
Coefficients that shift pressure direction
Surface coefficient Cp controls whether pressures act inward or as suction. Windward walls commonly use positive Cp, while leeward, side walls, and roofs often use negative Cp. This calculator lets you override Cp to match specific geometry or component zones.
Internal pressure envelope for enclosure conditions
Internal pressure can amplify or reduce net wall pressure depending on openings and leakage. The tool applies both positive and negative internal sign cases using |GCpi| to create an envelope. Partially enclosed conditions typically produce larger envelope ranges than enclosed buildings.
Story zones for force distribution with height
For preliminary lateral design, pressures can be converted into forces over height zones. Each zone uses its own Kz at the zone center elevation, then multiplies by zone tributary area. The governing signed zone force drives the approximate base overturning moment.
Use exposure D only for open-water fetch. For slender towers, dynamic effects may dominate. Treat this as screening before analysis structural modeling.
Interpreting results for coordination and checks
Use p+ and p− to check cladding demand and suction stability. Compare total story force trends when exposure, Cp, or G changes. If your model is sensitive to small coefficient edits, refine assumptions and confirm dynamic response with a detailed wind analysis. These planning outputs support early decisions and tender comparisons.
FAQs
1) What does Kz represent?
Kz is the exposure coefficient that increases with height. It reflects terrain roughness and controls how wind pressure grows from lower stories to the top.
2) Why are there p+ and p− results?
Net pressure depends on internal pressure sign. The calculator evaluates both internal cases and reports an envelope so you can check inward pressure and suction.
3) When should I override Cp?
Override Cp when your standard specifies different values for corners, parapets, canopies, or components and cladding zones. Use the correct sign for windward or suction surfaces.
4) How do I set the reference height?
Use the height relevant to the surface you are checking, often the top height for a full elevation. For panels, use the panel mid-height and custom tributary area.
5) Are the zone forces a full lateral analysis?
No. Zone forces provide a quick distribution for preliminary checks and coordination. Final design should include full height profiles, torsion, across-wind response, and code-specific load combinations.
6) How do the exports work?
After you calculate once, the tool stores the latest results for your session. Use Download CSV for spreadsheets and Download PDF for sharing in reviews.