As defined for rigid(>1Hz) or flexible(<1Hz) buidlings in ASCE 7-02, how we can calculate the natural or fundamental frequency of building? thx in advance
In the seismic section of the code, there is an approximate period, T = 0.1N where N = the number of stories in the building.
There is also a more direct approach. Many times, if your structure is a well defined frame system of some kind, some analysis/design software out there have the ability to calculate your major mode frequencies/periods and we have used these. (such as RISA-3D)
I like to add that STAAD Pro will calculate the natural frequency as well. However, I would use an approximate method if all I am interested in is the fn for wind load calculations.
