Wind Guest Factor - Analytical Procedure

Wind Guest Factor - Analytical Procedure

Gust Effect Factor

Gust effect factor, G, for buildings and other structures depends on whether a building is flexible or not. In Section 26.2 a flexible building is defined as one with fundamental natural frequency less than 1 Hz (period greater than 1 s). A building can be considered rigid if the fundamental natural frequency is greater than 1 Hz (period less than 1 s). Fundamental natural frequency depends on the structural system of the building as well as on construction materials. Approximate determination of frequency is given in Section 26.9.3. More discussion for approximate natural frequency is given in commentary Section C26.9 (Eqs. C26.9-6 through C26.9-15). These approximations vary by a factor of 2 or more. Design practices have software that can calculate fundamental frequency more accurately. For illustration purposes, this example assumes that the natural fundamental frequency is greater than 1 Hz; hence the building is considered a rigid building. Section 26.9.1 of the Standard permits use of 0.85 for gust effect factor, G, or calculate in accordance with equations in Section 26.9.4. In this example, G is calculated using equations.