Displacement-based seismic performance evaluation and vulnerability assessment of buildings: The N2 method revisited

Abstract

The so-called N2 method is a widely used nonlinear static method for the seismic design and/or assessment of different building typologies. In this paper, the idea of reversing the so-called N2 method currently adopted in the Annex B of Eurocode 8 (the code on which the present paper is based) in a direct displacement-based procedure is presented in a simple alternative format. In this way, it is possible to obtain the percentage of the seismic action associated to any performance displacement. By doing so, it is also possible to determine the target displacement without the need for an iterative procedure. The proposed method presents several advantages for professional engineering practice in respect to the seismic vulnerability assessment of new and existing buildings. The comparison of the original N2 method with the proposed one is illustrated by means of a test structure example.