Assessment of the design criteria for concentric V-braced steel structures according to Italian and European codes

The critical review of design methodologies provided by the NTC2008, in agreement with the European seismic code (Eurocode 8) for steel Concentrically Braced Frames with chevron (or inverted V) diagonals (CBF-V), carried out by deepening the seismic behaviour of such typical steel seismic resistant structures, aims to provide more efficient design criteria able to ensure adequate safety levels under seism. As reference case studies, common structural configurations of CBF-V are designed according to the NTC2008 provisions. Each case study is designed through both the Linear Static (LS) and Dynamic (LD) analysis. For braces either Circular Hollow Sections (CHS) or HE profiles are used. General critical issues have been evidenced in the design process. The seismic performance of investigated structures is evaluated by non-linear static analyses, in order to appraise the most relevant behavioural issues, like the behaviour factor, the failure modes and the effectiveness of the capacity design criteria. A discussion on the obtained results has allowed to point out the pros and cons of the current design approach.