ABSTRACT
In the past, several papers have investigated the opportunity to insert moment resisting frames (MRFs) into steel braced systems with the aim of improving the seismic behavior of the latter structures. In some cases the interaction between the two sub-structures has been considered to reduce the interstory displacements demanded by low intensity earthquakes (Martinelli et al., 1998) or the residual displacements caused by strong ground motions (Kiggins and Uang, 2006). In most cases, however, MRFs have been considered with the aim of smoothing the differences in the interstory inelastic displacements and reducing the sensitivity of the seismic response to variations in the mechanical characteristics of the structure and dynamic properties of the seismic input (Whittaker et al., 1988; Jain et al., 1993).
