The effect of the gravity column in the seismic design of steel CBFs

In this work, the effect of the gravity column in the seismic design of X-braced CBFs is analysed through a simplified design procedure. The analysis is performed by dividing the structural typology as a sum of two substructures: the Gravity Column (GC) substructure, with the primary aim of bearing vertical actions; and the Bracing substructure, mainly reacting to the horizontal actions. The analysis of the influence of the GC in the seismic design has been deepened by exploiting the Controlled Collapse Design Theory for CBFs. By imposing the collapse configuration, the storey displacement vector is obtained and, through the deformability matrix for the GC substructure, the horizontal actions acting on this substructure are defined. An analysis of the effects of seismic design is carried out considering the percentage of total shear force due to the GC substructure, for two case studies. In addition, a cost-(seismic) benefit analysis between the Controlled Collapse Design Theory and EC8 Design, is carried out.