Structural systems are prone to global as well as member imperfectionsrnin geometry. These imperfections are accounted for when consideringrnstructural stability and strength requirements of both sway and non-swayrnframes.rnIn the first part of this thesis, stability of imperfect systems is examined.rnWith the intention of understanding the ideas necessary to tackle morernpractical aspects of instability, stability of equilibrium are first introduced byrnanalysis of the behavior of some simple mechanical systems. Existence ofrnimperfection cause the maximum load to be attained to fall below the criticalrnvalue and the larger the imperfection, the larger is this reduction. Thernbifurcation point defines the form of instability of a structural system.rnFor simple mechanical systems, the behavior of the imperfect system isrngoverned by the magnitude and the sign of the imperfection and also therncritical load of the system without imperfection. In systems with more than onerndegree of freedom, it is the fundamental mode and load which governs thernelastic portion of the behavior frames possessing imperfection. The pattern ofrnimperfection of form and loading, considered as a whole determines the modernof buckling.rnTo evaluate strength requirements of imperfect structural systems, thernimperfection effects are quantified in terms of an initial sway imperfection atrnthe base of the column and then converted to equivalent horizontal forces.rnAnalysis is carried out which includes these equivalent horizontal forces andrnthe maximum bending moment in columns and beams for frames with varyingrnnumber of bays and number of stories are examined. For a fixed number ofrnstories, the effect on maximum bending moment in beams decreases withrnrnincreasing number of bays. The effect on columns is not as large as that onrnbeams but is still significant for high rise buildings. For fixed number of baysrnthe percentage increase rises with the story height.