Mitigation of Soft Storey Failure: A New Criteria

The definition of ductility classes DC of Eurocode 8 has been modified in the on-going revision process. DC1, without objective of plastic deformation capacity or energy dissipation capacity, is equivalent to the former DCL, on the contrary of DC3 which, like former DCM and DCH, requires those characteristics and imposes for moment resisting frames the “weak beams-strong columns” criteria. In DC2, the latter is not imposed, but soft storey failures have to be mitigated anyway; local overstrength capacity, deformation capacity and energy dissipation capacity are required; the control of the global plastic capacity is made through limitation of drift and of second order effects and, for moment resisting frames, by the respect, at each storey level, of a criteria showing that the storey possess the energy dissipation potential required for stability. The basis of this criteria is explained in the paper.