The endurance time method (ET) is a dynamic analysis procedure in which intensifying dynamic excitations are used as the loading function. Seismic performance is evaluated over the entire range of equivalent seismic intensities of interest in each response history analysis, considerably reducing computational demand. In this paper, a general methodology for performance-based retrofitting of typical steel frames by the ET method is discussed. A baseline steel moment-resisting frame is considered, and its seismic performance is evaluated by the ET method, considering viscous dampers and shear wall panels as strengthening alternatives. Each retrofitting option includes several design alternatives as well. The versatility of the ET method for this category of seismic design problems is demonstrated. Seismic performance, in conjunction with life-cycle costs, is employed to select the most appropriate alternative.
