Rigid-plastic analysis and moment–shear interaction for hierarchy criteria of inverted Y EB-Frames

• Theory of plastic mechanism control developed for inverted Y EB-Frames
• Rigid-plastic analysis of EB-Frames with inverted Y-scheme is carried out.
• Moment–shear interaction for to the development of simple hierarchy criteria
• Determine how to assure the yielding of predefined dissipative zones only
• The attention is focused on one-storey EB-Frames with inverted Y-scheme.

One of the primary purposes in structural design of seismic-resistant structures is the prevention of undesired collapse mechanisms, involving only a few storeys, which are not satisfactory in terms of energy dissipation capacity.The optimization of the seismic structural response can be achieved with a collapse mechanism of global type, because, in this case, all the dissipative zones are involved in the corresponding pattern of yielding, while all the other non-dissipative structural parts remain in elastic range. In order to promote the development of a collapse mechanism of global type, modern seismic codes provide simple design rules based on so-called hierarchy criteria. However, even though these simple criteria are able to ensure that “soft storey” mechanisms are prevented, they are not able to lead to the development of a collapse mechanism of global type. Therefore, more sophisticated design procedures based on rigid-plastic analysis have been proposed to assure such design goal.In this paper, within the framework of the theory of plastic mechanism control, rigid-plastic analysis of EB-Frames with inverted Y-scheme is carried out including moment–shear interaction aiming to the development of simple hierarchy criteria to be applied with reference to the single storeys to prevent undesired collapse mechanisms. Therefore, reference is made to the simple one-storey scheme. Conversely, the whole theory of plastic mechanism control for EB-Frames with inverted Y-scheme will be presented in a forthcoming paper dealing with multi-storey EB-Frames.Finally, the effectiveness of the proposed hierarchy criteria has been verified by several push over analyses.