ABSTRACT
Energy dissipation devices are used in bridge design against ultimate limit states, i.e. against the strongest design response spectrum the code introduces. They are conceived to serve as high stiffness components below a force threshold and to undergo large hysteretic cycles when the threshold is crossed. This paper discusses the selection of this threshold as the result of a cost-benefit analysis: lower the threshold is, higher the bridge reliability becomes. On the other side, lower the threshold is, higher the probability that the bridge devices undergo permanent deformation, under the serviceability excitation, becomes. The recent earthquake in Turkey produced a significant case study, which will be illustrated and discussed.
