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Damping for Static Seismic analysis

Damping for Static Seismic analysis

Damping for Static Seismic analysis

What would be the ideal damping % to be considered for a Steel structure.
Its a factory abot 60ft high frame , with the composite deck first floor at 36ft

I had designed the structure with 5% damping.

This is a typical bolted connection with heavy loads on the first floor, (25kN/m^2), and office space partition walls.

If I consider 2% damping, I see an increase of almost 40% in lateral forces and makes my structure uneconomical.

can experts plz share any relevant references that can justify 5% damping in such a structure?

RE: Damping for Static Seismic analysis

IF you are analyzing the structure for seismic, then the code specified damping is 5%. However, damping value should be less for dynamic analysis for wind, machinery or wave induced fatigue. Under those types of loading the structure essentially remains elastic and so the damping is relatively low. For a simple welded structure, this damping can be as low as 1/2%. However, as the size and complexity (such as number of connections, partitions, finishes, etc) of the structure increases, the damping also should go up but should still be less than that for seismic. For the type of structure that you are looking at, a 2% damping for loading other than seismic should be okay.

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