Problem #6:

GIVEN: One-story fire station planned near Florence, Oregon with a flat roof. Roof

height = 12 ft. This critical facility is in Risk Category IV (from OSSC Table 1604.5).

The building is rectangular and 50 ft. x 100 ft. in plan. It is situated right next to the

beach, and the 100 ft dimension is parallel to the coast. It is considered to be enclosed

per ASCE 7-16 Section 26.2.

FIND: The controlling wind design pressures (combining external and internal

pressures) to be used for the windward wall.

These should be pressures for design of the main wind-force-resisting system

(MWFRS) and not for the components and cladding. The MWFRS is composed of the

walls and roof as they resist the wind as a complete structural system. Components

and cladding are parts of the walls and roof as they resist the wind locally.


1) Section 1609 of the 2019 OSSC covers wind loadings. It will be used in combination

with appropriate sections in ASCE 7-16 that are briefly discussed in the Hibbeler text.

The necessary information from ASCE 7-16 will be provided here.

Individual MIV Set (Loadings): STRUCTURAL THEO (C6_381_001_F2022)

2) Use the 2019 OSSC to determine the Basic Design Wind Speed, V, for this location.

3) The Directional Procedure for MWFRS in an enclosed building is outlined in ASCE

7-16 Table 27.2-1. The definition of an enclosed building is provided in ASCE 7-16

Sections 26.2 and 26.12.

4) Velocity pressure exposure coefficient Kz = 1.03 for Exposure D (Table 26.10.1 in

ASCE 7-16) for z ≤ 15 ft. Directionality factor, Kg = 0.85 (Table 26.6-1 in ASCE 7-16-

note that this is different from the Hibbeler text). Topographic factor, Kat= 1.0 for flat

terrain (ASCE 7-16 Section 26.8.2). Ground elevation factor, Ke=1.0 for sea level and

to be conservative for all elevations. Gust effect factor, G=0.85 for rigid buildings and

other structures.

5) Internal pressure coefficient for enclosed building is from ASCE 7-16 Table 26.13-1

or from the Hibbeler text.

6) Velocity pressure exposure coefficient, K₂ is from Table 28.10-1 in ASCE 7-16 or

from wall pressure coefficient in Hibbeler.

7) Velocity Pressure qz or qn is from Eq. 28.10-1 in ASCE 7-16 or from the Hibbler text.

8) External pressure coefficient, Cp is from Fig. 27.3-1 in ASCE 7-18 or from the

Hibbeler text.

9) Design wind pressure on the wall is given by Eq. 27.3-1 for a rigid building in ASCE

7-16 or in the Hibbeler text.