RM Bridge inside OpenBridge Designer can calculate or define the Aerodynamic Admittance functions for the fluctuating wind buffeting forces for different mean wind incident angles of attack, as shown in the image below.

The frequency-dependent aerodynamic admittance functions model the dynamic wind loads as analytical and complex-valued functions. The admittance functions are provided in pairs, with the following type of dependency:

A_mn(ω)=1/[1+a_mn(Bω/u_∞)]^b_mn  {m=D,L,M; n=u,w

The general approach is used with additional assumptions for simplifications and some extrapolations while the frequency must be provided as a reduced frequency with a normalization length.

More information can e found in the document Aerodynamic Admittance Function for Wind Calculation.pdf and by running the example .tcl files.