A Seismic Design Procedure for Moment-Frame Structures

A procedure for the performance-based seismic design of moment-resistant frames is presented. The design procedure utilizes an estimate of the yield displacement of the roof in conjunction with yield point spectra to determine the required lateral strength. Beam strengths are established using a plastic mechanism approach, while a modified Portal Frame method is used to establish the strengths of critical sections of columns, considering the locations of inflection points and the desire to avoid weak-story mechanisms. An example illustrates the application to reinforced concrete frames. Due to the stability of the yield displacement, few (if any) iterations are needed.