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ASCE 7-22 Wind Velocity Pressure qz

↓ Visual explanation: interactive chart, 1 figure

Eq. 26.10-1, qz = 0.00256·Kz·Kzt·Ke·V². In ASCE 7-22 the directionality factor Kd is no longer in qz — it moved into the pressure equations. Many “ASCE 7-22” tools still put Kd here; applying it again in the pressure equation under-predicts pressure by 15%. Kz uses the ASCE 7-22 formula (coefficient 2.41) and the revised terrain constants.

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Kz Table 26.10-1—
Ke §26.9—
qz Eq. 26.10-1—

Kd (Table 26.6-1; 0.85 for buildings) is applied in the pressure equations, e.g. p = q·Kd·G·Cp − qi·Kd·(GCpi) (Eq. 27.3-1). Do not apply it to this qz and again later.

Table 26.10-1 Note 1Kz = 2.41(15/zg)2/α for z < 15 ft; 2.41(z/zg)2/α for 15 ft ≤ z ≤ zg; 2.41 above zg (ASCE 7-16 used 2.01). The formula is permitted; tabulated values may differ by ±0.01 from rounding.
Table 26.11-1Constants used — B: α = 7.5, zg = 3,280 ft; C: α = 9.8, zg = 2,460 ft (check: Kz(33 ft, C) = 1.00 by definition → zg ≈ 2,456 ft); D: α = 11.5, zg = 1,935 ft (single secondary source; within 1% of tabulated Kz). The zmin column of Table 26.11-1 is for the gust-effect factor, not a floor for Kz.
VerifyExposure B, ASCE 7-22-specific values at 50 / 100 / 200 ft: 0.79 / 0.95 / 1.14 (ASCE 7-16: 0.81 / 0.99 / 1.20). Published example: Exposure C, z = 15 ft, V = 100 mph, Kz = 0.85 → qz = 21.76 psf.
ScopeVelocity pressure only. Pressures and forces (Chapters 27–30), gust-effect factor, enclosure classification and tornado loads (new Chapter 32) are separate steps.

Visual explanation

Wind: growth of the velocity pressure coefficient with height. K_z by terrain roughness (exposure B, C, D); q_z = 0.613·K_z·K_zt·K_e·V² (Pa)
Figure 62. Wind: growth of the velocity pressure coefficient with heightSource: ASCE 7-22 Table 26.10-1 (site asce7-wind engine). Turkish TS 498:2021 profiles differ.

Preliminary calculation tool. Final design requires the full text of the referenced standard (see the sources on this page) and review by a licensed PE.