Part 3 - While buildings are usually designed for seismic resistance using elastic analysis, most will experience significant inelastic deformations under large earthquakes. Modern performance-based design methods require ways to determine the realistic behavior of structures under such conditions. Enabled by advancements in computing technologies and available test data, nonlinear analyses provide the means for calculating structural response beyond the elastic range, including strength and stiffness deterioration associated with inelastic material behavior and large displacements. This seminar is intended to provide a summary of the important considerations to be addressed, considering the current capabilities of nonlinear analysis technologies and how they are being applied in practice. The scope includes both nonlinear static (pushover) and dynamic (response history) analyses, but with the emphasis towards the latter. The guidance provided is generally consistent with building codes and standards, however, as the use of nonlinear analysis for design is still evolving, there are many areas where details of the implementation are open to judgment and alternative interpretations. The seminar builds off of material presented in NEHRP Seismic Design Technical Brief No. 4 - “Nonlinear structural analysis for seismic design” and related documents.