| A new method for the displacement-based design (DBD) of a variety of structures to resist the earthquake forces experienced by them is developed. The proposed method requires the determination of yield and ultimate displacements of the structure. For preliminary design these parameters are determined from approximate empirical relationships. The required strength of the structure is then determined from the inelastic demand spectrum corresponding to the ductility capacity and the estimated yield strength. The method can be used for a multi degree of freedom system by transforming it into an equivalent single degree of freedom system.; For final design, a modal analysis is carried out on a model of the structure that is based on its preliminary design. A pushover analysis of the structure for forces that are distributed according to the first mode now provides better estimates of the yield and ultimate displacements. These refined estimates are then used to obtain a more precise value of the required strength. Iterations may have to be carried out to obtain convergence between the assumed and calculated values of the design displacements. Finally, to account for the effect of higher modes in shear wall structures and high-rise moment resisting frames, the standard modal pushover analysis (MPA) method available in the published literature is used.; Nonlinear time history analyses of the structures designed according to the proposed DBD method are carried out for sets of ground motions that are compatible with the design response spectra. Procedures for the selection and scaling of the spectrum compatible ground motions are studied. A set of such ground motions that is compatible with the UHS of Montreal corresponding to a probability of exceedance of 2% in 50 years is developed as a part of the present research. This set and a similar set for Vancouver, developed in another research study, are used in time history analyses, first to develop relationships between inter-story drift and roof drift, and second to validate the proposed DBD method. |
