Sway and non-sway in frames

A frame is considered to be non-sway (braced) if it is sufficiently braced by lateral bracing elements like structural walls. On the other hand, frames that provide lateral resistance only through columns are considered to be sway frames (unbraced). ACI 318-19 can be used as a reference to distinguish between sway and non-sway frames. It should be noted that purely sway and non-sway frames rarely exist in practice, hence, the design should be prepared based on the requirements. For instance, the designer should decide in advance if the bracing provided by shear walls, elevators, utility shafts, stairwells, or other elements would be sufficient to limit the structure against significant sway effects. It is possible that a particular storey in a structure could be sway while another is non-sway.