Effective damping and frequencies of viscous damper braced structures considering the supports flexibility

•A new approach for optimal sizing of flexible brace-damper assemblies is proposed.•Can be seen as an add-on to current methods that do not increase their complexity.•The brace stiffness is included as a design parameter in the optimisation.•Variations on damping and frequencies due to damping braces can be easily assessed.•This tool enables engineers to make rapid informed decisions on brace/damper sizes.•Advantages are demonstrated using a real case study taken from the literature.