Investigation on the equivalent viscous damping in direct displacement-based design

It is generally stated that an accurate evaluation of the equivalent viscous damping is a crucial step in the Direct Displacement-Based Design (DDBD) methodology. In such a context, the main objective of the present contribution is to assess and compare different existing equations aiming at evaluating the equivalent damping and to provide information of the practical consequences of choosing one or another of these equations in the design process.