Displacement Estimates for Performance-Based Seismic Design

Abstract

New analysis and design procedures have been developed for the performance-based seismic rehabilitation of buildings. Such procedures require accurate estimates to be made of displacements, velocities, and accelerations. Nonlinear response-history analysis of single-degree-of-freedom oscillators, having varying values of yield strength and post-yield stiffness and using 20 velocity-scaled earthquake ground motions, was undertaken to verify the accuracy of the proposed displacement-estimation procedures that make use of relations between inelastic and elastic displacements. Near-field earthquake records were not considered. The assumption that mean inelastic displacements are approximately equal to mean elastic displacements is reasonable for oscillators with strength ratios greater than 0.20 and elastic periods greater than the characteristic site period. For other values of the strength ratio and elastic period, the assumption is nonconservative. Mean-plus-one-standard-deviation inelastic displacements are approximately equal to 1.5 times mean inelastic displacements for elastic periods greater than 0.3 s.