ABSTRACT This paper follows a novel line of research focused on the integral design of steel frames and stairs, according to architectural, structural, and seismic criteria. This approach takes advantage of the elastic response of moment‐resisting frames located in facades (lateral rigidity, torsional inertia, and self‐centering capacity) combined with the ductility provided by the plastic deformation of stair bracings. As shown in previous research, special braced stairs provide lateral rigidity and ductility to buildings with moment‐resistant frames. However, the concentric bracings of multistory staircases in tall buildings can cause large axial forces on base columns. For column failure prevention, the concentric bracings of stairs can be connected to primary beams. Therefore, the research is based on a 15‐story building with special braced stairs, proposing new design rules for steel bracings, and a seismic (deterministic) numerical analysis. Three methods of analysis proposed in Eurocode 8 are used: (a) the linear‐elastic modal analysis, (b) the static nonlinear (pushover) analysis combined with the capacity spectrum method, and (c) the nonlinear time history (dynamic) analysis (direct integration method). The numerical analysis verified the structural safety of stairs and frames, preventing the torsional effects of the third vibration mode, respecting the damage limitation according to the peak interstory drifts and controlling the seismic performance levels in all steel members. The satisfactory results obtained show the effectiveness of the new SBS as a novel seismic damping system.
Carlos Montalbán Turon (Fri,) studied this question.