Seismic Design Based on the Yield Displacement

Although seismic design traditionally has focused on period as a primary design parameter, relatively simple arguments, examples, and observations discussed herein suggest that the yield displacement is a more stable and more useful parameter for seismic design. The stability of the yield displacement is illustrated with four detailed examples, consisting of moment-resistant frame buildings. Each frame is designed to limit roof drift for a specific ground motion using an “equivalent” SDOF model in conjunction with Yield Point Spectra. The effectiveness of the simple design method is established by nonlinear dynamic analysis. Yield displacements were stable and consistent while the fundamental periods of vibration (and lateral stiffness) required to meet the performance objective differed substantially.