Influence of P-delta effect on dynamic response of high-rise moment-resisting steel buildings subject to extreme earthquake ground motions

We study the influence of the P-Δ effect on the dynamic response of 20 story moment-resisting steel frames under extreme earthquake ground motions. In this paper, we perform nonlinear time-history analyses of 3 frame models having different design base shear. The major findings include: (a) If the design base shear was close to the lower bound of existing buildings, deformation in lower stories accumulated in one direction under a synthetic long-period earthquake ground motion. This led to significant residual story drift, (b) The deformation accumulation was suppressed by increasing the post-yield stiffness, (c) The deformation accumulation occurred even if the columns are all elastic except the base of the 1st story.