Hello,
As per the SNIP code, “ The total wind pressure consists of static and fluctuating components. If the structure is sufficiently flexible, according to the code provisions, the dynamic structural response to the fluctuating wind component must be taken into account. “
“Additionally, as part of the load force is determined from the dynamic behavior of the model, the first load case that includes a Russian Wind Load specification also needs to include all the masses that can cause the structure to vibrate from which a dynamic analysis will be used to extract the mode shapes. “
Please go through article AD.V8i.2 of the Technical Reference Manual . Screenshot attached .