The Effect of Easy-Going Steel on KBF's Seismic Behavior

The knee bracing steel frame (KBF) is a new type of energy dissipating frame which enjoys exceptional ductility and lateral stiffness. Rather than the beam-column joint, one end of the diagonal brace in KBF is attached to the knee element. Indeed, the knee element as a hysteretic damper is designed and detailed to behave like a structural fuse by sustaining controlled inelastic deformations as well as by dissipating seismic energy, yet other parts and connections remain elastic. Simultaneously, the lower strength steel is utilized in knee element based on the general concept of easy-going steel (EGS). As the current paper takes into account the effect of easy going steel on KBF's response modification factor, several frames with similar dimensions but varying heights are designed based on the Iranian code of practice. For this purpose, initially the knee elements are substituted with the one made of EGS and subsequently the seismic parameters such as response modification factor and seismic performance levels are compared based on non-linear incremental dynamic analysis (IDA). The average values of response modification factor for these frames have been obtained 11.4 and 11.6 for KO and KE frames respectively. The results reveal that the frames' stiffness and ductility factor with EGS augments by 10% and 6% respectively.