Seismic Behavior of Moment‐Resisting Steel Frames: Analytical Study

An analytical investigation into the seismic performance of steel moment‐resisting frames is presented. The International Conference of Building Officials (ICBO) provisions regarding seismic design of steel moment frames are summarized, and potential problems and discrepancies are noted. The results of prior research are reviewed, and prototype three‐, eight‐, and 20‐story frames are designed by an experienced designer. The inelastic responses of these frames are then determined for a range of different earthquake acceleration conditions. The analysis shows that strong‐column weak‐beam (SCWB) frames result in much smaller story drifts and better distribution of inelastic deformation and energy dissipation among elements in the structure than comparable weak‐column strong‐beam (WCSB) frames. The difference was most significant with earthquake acceleration records that cause significant yielding. Steel frames performed adequately if a spine of SCWB joints is used over the height of the structure. The computed results were compared to the results of past experiments. The comparison suggests the SCWB frames should be capable of sustaining the required deformations. The comparison did not provide a clear answer for WCSB frames, and so a series of experiments were performed. These experiments are described in the companion paper.