Effect of Span Length on the Seismic Design Modification Factors of Steel Frames with High Ductility

Seismic design modification factors (SDMFs) control the estimated force and displacement to structures during seismic events. codes recommend similar SDMFs for short andlong-span structures. Therefore, this study investigated effect of span length on steel frames with high ductility. For purpose, nine three different lengths 5, 10, 15 m were selected designed according specifications ASCE/SEI 7-16. The single, double, three-story frames. obtained results showed that values response factor (R), overstrength (Ω), deflection amplification (Cd) increased as was increased. Besides, an increase in number stories decreased value R Ω-factors. It concluded inelastic long-span might be underestimated if given Cdvalues code used.