Displacement-based energy dissipation systems for steel bridges diaphragms

A seismic design strategy that relies on ductile end-diaphragms inserted in the steel superstructure can be, in some instances, an effective alternative to energy dissipation in the substructure. This could be the case, for example, when stiff wall-piers that can difficultly be detailed to have a stable ductile reponse are used as substructures. Such a ductile diaphragms concept was originally developed for the seismic retrofit of steel slab-on-girder and deck-truss bridges. For application in new bridges, the proposed retrofit methodologies were revised and convert into design procedures. This paper provides an overview of these design procedures developed as part of an NCHRP project.