Seismic design criteria for Chevron CBFs: European vs North American codes (Part-1)

Chevron concentrically braced frames are one of the most cost-effective solutions for seismic resistant steel buildings. Therefore, this system is widely used in Europe and North America. Both European and North American codes adopt capacity design rules aiming at enforcing the dissipative behaviour into the braces and at preventing the damage in the remaining structural members. However, in order to achieve this purpose, European and North American codes recommend some different requirements and detailing rules, which substantially influence the overall performance and energy dissipation capacity. The research presented in this paper is addressed (i) to verify the effectiveness of the design requirements prescribed by Eurocode 8 (EC8) compared to North American codes (i.e. both AISC 341 and CSA-S16), (ii) to identify the criticisms of EC8 needing revision and upgrading. In order to achieve these objectives, a comprehensive parametric numerical study based on nonlinear dynamic analyses is carried out. 2D frames extracted from low, medium and high-rise buildings are analysed and the main structural parameters affecting the performance against lateral loads are described and discussed. The critical review of the examined standards and the discussion of numerical results highlight that the design rules given by North American codes are more effective than those recommended by the current version of EC8. In particular, EC8-compliant frames show the poorest energy dissipation capacity with tension bracing members almost in elastic range and severe demand on those in compression. On the contrary, both CSA- and AISC-compliant cases exhibit satisfactory energy dissipation capacity.