Jacobsen's equivalent damping concept revisited

The equivalent damping concept originally proposed by Lydik Jacobsen in 1930 is revisited in order to be of use in the seismic analysis of building structures. After briefly recalling that the equivalent damping is obtained by a linearization of a frequency response transfer function and can be deformation-dependent, the paper is then focused on its potential application. In particular, the equivalent damping is employed a) to estimate the maximum seismic displacements of first-mode dominant structures, b) in linear modal analysis, c) in response spectrum analysis and d) in energy-based considerations. Examples are provided highlighting the aforementioned applications of the equivalent damping concept, aiming to retrieve the interest of the engineering community.