ASCE 7-22 Wind Load: Velocity Pressure and MWFRS Design per Chapter 26

Example

A Risk Category II office building is 80 ft × 60 ft in plan with 30 ft mean roof height. Basic wind speed 115 mph, Exposure B. Determine velocity pressure qh for MWFRS design per ASCE 7-22 Chapter 26.

How StructSuite solves this

StructSuite's free ASCE 7 wind load calculator applies Chapter 26: Risk Category (§26.2), Basic Wind Speed (Figure 26.5-1), Ground Elevation Factor Ke (Table 26.9-1), Velocity Pressure Coefficient qh (Table 26.10-1), Velocity Pressure Equation 26.8-1. Live example widget for wind module is in development.

Steps

1. Step 1: Determine risk category of building

   Design consideration: V drives q ∝ V²—115 mph vs 130 mph = 28% higher pressure. Risk Category affects importance factor. Coastal (130–170 mph) and hurricane (180 mph) require robust connections. Inland 90–115 mph typical.

   In StructSuite: In Step 1, use the Risk Category dropdown to select I, II, III, or IV (e.g., II for offices, residential). In the Basic Wind Speed (mph) input box enter 115. Per ASCE 7-22 §26.2, Figure 26.5-1. If using address lookup, use the address search to auto-fill wind speed.

2. Step 4: Velocity pressure exposure coefficient

   Design consideration: Mean roof height h sets Kh: higher h = higher Kh (velocity increases with height). 30 ft in Exposure B: Kh≈0.70. Low-rise (h≤60 ft) can use simplified Ch 28; taller needs Ch 27 Directional. Plan dimensions set zone widths for pressure coefficients.

   In StructSuite: In the Building dimensions section, in Building Length (ft) enter 80; in Building Width (ft) enter 60; in Mean Roof Height (ft) enter 30. These drive Kh from ASCE 7-22 Table 26.10-1.

3. Step 3: Wind load parameters

   Design consideration: Exposure B (suburban): Kh lower. C (open): ~30% higher qh than B. D (waterfront): highest. Site within 1500 ft of open water triggers D. Kzt: ridge/escarpment can double pressure at crest. Ke for elevation >1000 ft.

   In StructSuite: In Step 3, use the Exposure dropdown to select B, C, or D. If ground elevation > 1000 ft, use Table 26.9-1 for Ke. For topographic features (hills, ridges), use the Kzt section and enter parameters from ASCE 7-22 Figure 26.8-1. Kd = 0.85 for MWFRS is typical.

4. Step 5: Velocity pressure at mean roof height

   Design consideration: qh = 0.00256×Kh×Kzt×Ke×V². qh multiplies pressure coefficients (GCpf, GCpi) to get design pressure. Doubling qh doubles all zone pressures—connections, diaphragm, hold-downs scale with qh.

   In StructSuite: In Step 5, the velocity pressure qh is auto-calculated from ASCE 7-22 Eq 26.8-1. Review the displayed value. Open Step 6 for external pressure coefficients (load cases 1–4); open Step 7 for design pressure results by zone.

Live design (pre-filled)

The form below is the real StructSuite module with example data loaded. Display only—values cannot be changed.