Calculating Frequency for Light Gauge Building 1

[dmersim]

Hello,

I'm working on a building where I need to calculate the wind load of a building. The walls are comprised of cold formed steel with gyp for shear walls.

I need to calculate the frequency of the building.

My two questions are, how can I determine whether the building is rigid or not, and how can i calculate the frequency of the building?

The applicable code needs to be for NYC if possible.

Any code references would be helpful.

Thank you

 

[Agent666]

Look into the Rayleigh method for determining the natural period. This method estimates the first mode period based on a force & corresponding deflection at each level. Similarly, there may be some basic assumptions in your area for the use of gypsum shear walls, like assume period is 0.4 seconds. Generally these types of systems if there are plenty of walls tend to being fairly short period structures.

Then frequency = 1/period

 

[phamENG]

Take a look at ASCE 7 wind load provisions. There are approximations there that can be used for that type of building. Just don't mix them up with seismic. I don't recall which is which, but over estimating the frequency for one will yield unconservative results, and under estimating for the other will do the same. That's why the frequency used for each is a little different for the same building.