Direct Displacement Procedure for Performance-Based Seismic Design of Multistory Woodframe Structures

Keywords: Performance-based seismic design (PBSD).  Direct displacement design (DDD).  Multistory structures.  Woodframe structures.  Interstory drifts.  Nonlinear dynamic time-history analyses.

Abstract: This report presents a displacement-based design procedure that can be used for performance-based seismic design (PBSD) of multistory woodframe structures.  In the design process, the acceleration response spectrum is converted into a set of interstory drift spectra which is used to determine the minimum stiffness required for each floor in order to maintain the drift level below certain design limits.  The structure is assumed to have symmetric plan and rigid diaphragms, assumptions that greatly simplify the analysis (i.e., no torsional effects), and yet are reasonable for most wood structures of regular plan.  As an illustrative example, the design of a three-story woodframe structure is presented.  The validity of the proposed direct displacement design (DDD) procedure is confirmed using results from nonlinear dynamic time-history analyses of the complete structure.  The target DDD interstory drift profiles closely matched the average peak interstory drifts from the time-history analyses.