Multistory Frame Design Using Story Stiffness Concept

Irrespective of the design philosophy employed in proportioning unbraced multistory steel frames, the selection of member sizes can be greatly expedited with the aid of the story stiffness concept. Bending moments, P-Δ effects, sway buckling, and lateral instability are all functions of the story stiffness parameter. The use of this concept eliminates the difficulties generally encountered in the direct inclusion of P-Δ effects in design. The significance of the story stiffness concept in allowable stress design and plastic design is demonstrated.