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Lateral & SeismicASCE 7-22 Chapters 26 and 27, Part 1 (Directional Procedure)

Wind Load — MWFRS (Directional Procedure)

Compute wind pressures on the Main Wind Force Resisting System (MWFRS) for an enclosed or partially enclosed regular-shaped building using ASCE 7-22 Chapter 27 Part 1 (Directional Procedure). Determines velocity pressure at each height, external pressure coefficients for windward, leeward, side walls, and roof, and combines them with internal pressure to obtain net design pressures on each building surface.

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What this calculates

Basic wind speed (V) based on Risk Category, velocity pressure exposure coefficient (Kz) at each height per Table 26.10-1, velocity pressure qz = 0.00256·Kz·Kzt·Kd·Ke·V², external pressure coefficients (Cp) per Figure 27.3-1, internal pressure coefficient (GCpi), and net design wind pressure p = q·G·Cp − qi·(GCpi) on each surface.

Inputs

Basic Wind SpeedV[mph]

3-second gust wind speed per ASCE 7-22 wind speed maps

Exposure Category

Exposure B, C, or D per Section 26.7

Building Heighth[ft]

Mean roof height

Building WidthB[ft]

Building width perpendicular to wind

Building LengthL_bldg[ft]

Building length parallel to wind

Roof Slopeθ[deg]

Roof slope angle

Topographic FactorKzt

Topographic speed-up factor (1.0 for flat terrain)

Wind Directionality FactorKd

Directionality factor per Table 26.6-1 (0.85 for buildings)

Enclosure Classification

Enclosed, partially enclosed, or open

Outputs

Velocity Pressure at Roofqh[psf]

Velocity pressure at mean roof height

Windward Wall Pressurep_ww[psf]

Net design pressure on windward wall at roof height

Leeward Wall Pressurep_lw[psf]

Net design pressure on leeward wall

Roof Pressure (upwind)p_roof[psf]

Net roof pressure in the upwind zone

Total Base Shear (wind)Vw[kip]

Total wind base shear on the building

Methodology

Per ASCE 7-22 Chapter 26 (wind speed, exposure, topography) and Chapter 27 Part 1 (Directional Procedure for MWFRS). Risk category determines the basic wind speed map used. Exposure category (B, C, or D) determines Kz profile per Table 26.10-1. Topographic factor Kzt per Section 26.8. Wind directionality factor Kd per Table 26.6-1. Ground elevation factor Ke per Section 26.9. Gust-effect factor G per Section 26.11 (rigid buildings G = 0.85). External pressure coefficients Cp from Figure 27.3-1 for windward, leeward, sidewall, and roof surfaces.

Code References

ASCE 7-22 Chapters 26 and 27, Part 1 (Directional Procedure)

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