K-value for column in Dual System Structure

[whymrg]

What is K-value for the columns in Dual Sistem Structure with Special Moment Frames and Eccentrically (or Concentrically) Braced Frames (System 4 Table 1617.6 p. 367 IBC-2000) ?
Is Sidesway Inhibited or Uninhibited for columns in such structures?
Thanks.

 

[JAE]

I would think it depends on which column in the structure is being considered....they do vary within any given structure.

I have always understood that sway is considered IF the lateral stability of the frame DEPENDS on the bending resistance of the column fixed to the beam.

So a column in a moment frame provides the key lateral resistance to the frame and thus, sway occurs in the column and you must consider that as the condition.

For a column in a frame that does not provide frame lateral restraint through bending, then the column is "going along for the ride" and is considered braced by external systems and thus is in a non-sway condition.

In a dual system you still have to look at the contribution of the column to the lateral stability of the structure.