The performance level of low and medium-rise steel frames designed according to the common force/strength approach of the UBC or NEHRP is determined. Several combinations of soil profile type, lateral-force-resisting system, and frame-member proportioning are included in the designs.

To evaluate the expected damage, nonlinear models of the designed frames are subjected to a number of actual and simulated ground motion accelerograms and appropriate structural response parameters such as, interstory drift, ductility demand, and dissipated hysteretic energy are obtained. In addition, a modified form of Park-Ang damage index is calculated for moment-resisting frames. The seismic performance of the steel frames is assessed in accordance with the acceptance criteria of the NEHRP Guidelines for the Seismic Rehabilitation of Buildings (FEMA-273) which sets forth plastic rotation and deformation limits to define the performance levels for various structural and nonstructural components.

The effect of vertical component of ground motion, geometric nonlinearity, participation of nonstructural elements, and damping representation on the seismic response of steel frames is investigated. Based on the results of the dynamic nonlinear analyses, a simple procedure is proposed which uses the pushover analysis method to estimate the average maximum interstory drift. The method defines a damage index which, after being calibrated, can directly be used for performance evaluation.