Critical discussion of DC2 design rules for MR-Frames in the framework of the prEN1998 draft

Abstract

This work aims at analysing the design rules proposed for DC2 ductility class, introduced in the new prEN1998 draft, that is a new class intermediate between the low and hight ones. Simplified design rules aimed only at avoiding the so called soft-storey mechanism are proposed, because it is considered unnecessary to follow design rules that aim at the development of a global mechanism as occurs in the high ductility class. In particular, the design condition which is the statement of the DC2 design is based on an inequality that must be satisfied at all the storeys, which both does not consider the beam-column hierarchy criterion and does not possess any scientific background. This work aims to highlight the design rules proposed for MRFs in this new ductility class by carrying out a critical analysis. The attention is mainly focused on the soft-storey mitigation criterion and its application in a study case that represent the novelty of the paper.