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

Panel zones can be proportioned to be weak, balanced, or strong. Damage of steel SMFs during past earthquakes highlighted the limitations of weak panel zone design leading to its discontinuation from design practice. Thereafter, balanced and strong panel zone approaches became acceptable. However, the shear demand and capacity for which the panel zones need to be proportioned to achieve a balanced or strong panel zone still remains ambiguous. In this paper, three different panel zone design approaches are investigated (called PZ-I, PZ-II, and PZ-III), by incorporating them in seismic design of select study buildings. The shearing behaviour of the panel zones are evaluated using results of nonlinear analyses, which indicate PZ-I, PZ-II, and PZ-III lead to weak, balanced, and strong panel zone behaviour, respectively. In particular, PZ-I design leads to excessive shearing distortions in panel zones. Hence, it will be appropriate to adopt PZ-II or PZ-III design to either limit or entirely eliminate inelasticity in panel zones of steel SMF buildings. Finally, it is recommended that adopting PZ-II design approach would suffice for moment frame buildings in regions of moderate seismicity.