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Nonlinear static analyses based on either inelastic or elastic spectra with equivalent viscous damping: A parametric comparison Enzo Martinelli, , Ciro Faella Highlights • The paper proposes a systematic comparison between CS Method and the N2 Method. • A dimensionless formulation is firstly derived for making both methods comparable. • A systematic parametric comparison in terms of predicted ductility demand is proposed. • The general trends of predictions deriving from the two methods are pointed out. • NLTH analyses are proposed to assess the accuracy of the two aforementioned methods. Abstract In the last decade, nonlinear static procedures emerged as the reference practice-oriented analysis method for structures under seismic actions. These procedures are generally based upon two key steps: (i) performing a nonlinear static (pushover) analysis under lateral forces and (ii) evaluating the seismic demand through the so-called capacity spectrum obtained at the end of the previous step. This paper specifically deals with the latter and proposes a parametric comparison between two wide classes of methods formally based on conceptually alternative approaches for defining the demand spectra in nonlinear static analyses of dissipative structures. First of all, the paper outlines the main conceptual aspects of such alternative methods and reports their key operational details. Particularly, it proposes a dimensionless formulation of their relationships and demonstrates that both methods are based upon a small and almost common set of dimensionless parameters. Therefore, a wide parametric analysis is proposed to compare the ductility demand obtained by means of these two alternative methods with the aim of describing and quantifying the different predictions obtained by applying such methods. Finally, the results of nonlinear time-history analyses are proposed for assessing the two aforementioned methods. Keywords Capacity spectrum; Hysteretic dissipation; Viscous damping; Parametric comparison ES2015_PrePrint.pdf