Simplified design approaches for panel zones in steel special moment frame buildings

Panel zones (PZs) can be proportioned to be weak, balanced or strong. Damage to steel special moment frames (SMFs) in past earthquakes has highlighted the limitations of weak PZ design, leading to its discontinuation from design practice. Balanced and strong PZ approaches remained acceptable, but the shear demand and capacity for which PZs need to be proportioned to achieve a balanced or strong PZ still remain ambiguous. In this work, three different PZ design approaches were investigated (named PZ-I, PZ-II and PZ-III) by incorporating them in seismic design of selected study buildings. The shearing behaviour of the PZs was evaluated using the results of non-linear analyses, which indicated that PZ-I, PZ-II and PZ-III led to weak, balanced and strong PZ behaviour, respectively. In particular, PZ-I design was found to lead to excessive shearing distortions in the PZ. Thus, in order to either limit or entirely eliminate inelasticity in the PZs of steel SMF buildings, it is appropriate to adopt PZ-II or PZ-III design. It is recommended that adopting the PZ-II design approach would suffice for moment frame buildings in regions of moderate seismicity.