Seismic Hysteretic Energy Distribution in the Members of Multi-Story Steel Moment-Resisting Frames Resting on Stiff Soils

This paper numerically investigates the seismic input and hysteretic energy demands of moment-resisting frames resting on stiff soils under seismic actions. After modeling four benchmark steel frames with three, six, nine, and 20 stories, a set of 22 historical ground motion records was employed for the nonlinear time history analyses of each frame. The results revealed that the hysteretic-to-input energy ratio varied significantly across ground motions and structural configurations, ranging from 6.3% to 79.3%, emphasizing the record-dependent nature of energy demands. In addition, to better evaluate the localized energy dissipation mechanism, the story-wise and member-wise hysteretic energy distributions were discussed. Story-wise evaluations showed that the first story generally dissipates the most hysteretic energy, while member-wise analyses highlighted interior beams and first-story columns as key energy dissipation elements. Comparisons with widely used literature formulation for the story-wise distribution revealed that they might not accurately forecast energy distribution, especially in frames with varying member sizes along their height. The study, while limited to a specific site and soil class, highlights the limitations of using fixed energy distribution patterns and underscores the necessity for developing record-dependent and structure-specific formulations to improve energy-based seismic design approaches.