Italian and European guidelines for seismic design of isolated bridges

ABSTRACT

In the past few years official guidelines have been issued in Europe and in Italy to regulate the design of (passively) isolated bridges. Explicity covered is the use of elastomeric and elato-plastic elements. The design philosophy aims at ensuring adequate protection with respect to two Limit-States or Perfomance Levels the first one being the limit of fully elastic response, the second one being a state where the structure is still undamaged while the isolating elements are close to their ultimate deformation. Capcity design measures are adopted to ensure the protection of the structural parts even for larger-than-anticipated seismic events. Detailed requirements on the behaviour of the isolating elements so that they can reliably fulfil their protective role are given. Modelling, methods of analysis and verification criteria complete the content of the Guidelines. Aspects requiring improved definition are discusses in the conclusions of the paper.(AU)