Assessment of rigid steel frames: ductility versus damageability

Modern seismic code relies on the capacity design approach to assure ductility. When the capacity design dictates, the frames are dimensioned for strength. Inadvertently, stiffness often presents itself as a dominating parameter in MRFs (Moment Resisting Frames), especially with strict drift limits. In this research, rigid steel moment-resisting frames have been designed as per Eurocodes provisions. Initially, the results obtained from modal analysis and nonlinear analyses are concisely elaborated in such a way to highlight the complexities of Eurocode 8 design procedures. Various parameters are assessed to evaluate their influences on high and medium ductility classes. A simplified predictive method is proposed through tables, graphs, and flowcharts. Several combinations are suggested where for an assumed ductility class, a specific drift limit is defined. The elastic overstrength, redundancy factor, and reserve overstrength factors are indicated with the confidence to allow an un-iterated design approach for steel moment-resisting frames designed with a pre-determined strategy for failure mechanisms by improving the design approach of Eurocode 8.