ASCE 7-22 Wind: Chapter 27 Directional MWFRS for Partially Enclosed Warehouse

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ASCE 7-22 Wind: Chapter 27 Directional MWFRS for Partially Enclosed Warehouse

Summary: Chapter 27 Directional Procedure with partially enclosed enclosure classification, higher internal pressure, and height z for the highest opening per…

Overview

Building / scenario

  • Occupancy / use: Warehouse, Risk Category II
  • Geometry / size: 100 ft × 80 ft, h = 28 ft, flat roof
  • Site / exposure: Exposure C, partially enclosed, V = 115 mph

Problem statement

A Risk Category II warehouse is 100 ft long by 80 ft wide with a flat roof and mean roof height h = 28 ft. A large roll-up door on one long wall can create a partially enclosed condition. Ultimate design wind speed V = 115 mph, Exposure C, K_d = 0.85, K_e = 1.0, K_zt = 1.0. The building is classified as partially enclosed per Section 26.12; use GC_pi = ±0.55 per Table 26.13-1. For Chapter 27 Section 27.3.1, take the height of the highest opening for positive internal pressure as z = 22 ft above ground (typical large door head height). Use z = 28 ft for windward wall q_z for the windward surface at full height unless a smaller controlling strip is specified. Determine MWFRS design pressures using the Directional Procedure.

Workflow in StructSuite

Select Chapter 27. Enter Risk Category II, V = 115 mph, Exposure C, K_d = 0.85, K_zt = 1.0, K_e = 1.0. Set enclosure to partially enclosed and GC_pi = 0.55. Step 4: h = 28 ft; Step 5: q_z. Step 6: 100×80 ft, flat roof, θ = 0°; Step 4 shows Roof angle = 0.00°; enter highest opening height z = 22 ft and windward z = 28 ft. Step 7: Equation 27.3-1 pressures and Section 27.1.5 minimum loads (16/8 psf for enclosed/partially enclosed). Step 8: Figure 27.3-8.

Design considerations (excerpt)

Warehouses with large doors are often partially enclosed or require a rational analysis when the door is open; the selected classification must match the load case in the permit set. Chapter 27 Section 27.3.1 uses q_z at the height of the highest opening for positive internal pressure when partially enclosed—this can significantly increase net pressure on the roof and leeward wall compared to enclosed.

115 mph with partially enclosed GC_pi amplifies net pressure changes versus ±0.18. Door and opening schedules should be consistent with the classification stated in the wind load calculation.

Flat roof and long span diaphragms: large plan dimensions increase total shear to the lateral…

Related terms

  • StructSuite
  • structural engineering
  • design example
  • wind
  • ASCE 7-22
  • MWFRS
  • chapter27 partial warehouse

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