Seismic design approaches for panel zones in steel moment frames

The seismic behavior and design approaches of panel zones in moment-resisting steel frames are examined in this article. An in-depth review of previous and current European and North American panel zone design rules is firstly carried out and the main differences between the various procedures are discussed. A detailed numerical investigation into the inelastic behavior of moment frames incorporating panel zone response is then undertaken in order to assess the influence of a number of key parameters. The results obtained indicate the suitability of adopting 'balanced' design approaches, such as those proposed in recent North American provisions for the panel zone. In contrast, 'weak' panel zone designs often result in excessive distortional demands which can lead to unreliable performance of connection components. The findings of this study point out to some limitations in current European guidelines particularly in terms of the overestimation of panel zone capacity in Eurocode 3 which unintentionally results in relatively weak panel zones. The numerical studies also illustrate the important role that can be played by the level of gravity loading applied on the beams. This effect, which is not addressed in any of the current provisions, is shown to have a significant influence on the lateral response, and is therefore necessary to account for in codified design guidance.