A design procedure for dual eccentrically braced systems: Analytical formulation

Dual systems constituted by eccentrically braced frames and moment resisting frames are considered in this paper to improve the seismic behaviour of structures with conventional eccentric bracings. The design procedure proposed for such dual structures follows the force–design approach and complies with the capacity design principles. It is formulated so as to ensure seismic performances which are more satisfactory than those usually produced by current code regulations. In particular, the proposed procedure aims at inelastic responses characterised by fairly uniform ratios of required to available plastic link rotations and by substantial insensitivity to realistic variations of the mechanical properties of steel and dynamic characteristics of the earthquake ground motion.

► A design procedure for dual systems consisting of EBFs and MRFs is described.
► The procedure aims at the exploitation of the deformation capacity of all links.
► The MRFs are allowed to experience moderate inelastic behaviour.
► The procedure offers immediate control over the effect of cross-section changes.
► Only a few iterations are required to reach convergence in the design process.