Gust Effects (Section 26.11)

A building is considered as rigid if structure fundamental frequency is greater than or equal to 1 Hz. It is considered as flexible if the frequency is less than 1 Hz. Note that the program determines types of building (rigid or flexible) for each orthogonal direction, separately.

The gust-effect factor for rigid buildings is either 0.85 or it is calculated according to Section 26.11.4.

G = 0.925 (\frac{1 + 0.7 g_{Q} I_{\bar{z}} Q}{1 + 0.7 g_{v} I_{\bar{z}} Q})

(26.11-6)

The gust-effect factor for flexible buildings is calculated according to Section 26.11.5.

G_{f} = 0.925 (\frac{1 + 1.7 I_{\bar{z}} \sqrt{g_{Q}^{2} Q^{2} + g_{R}^{2} R^{2}}}{1 + 1.7 g_{v} I_{\bar{z}}})

(26.11-10)