Review of the evolution of the ductile diaphragm concept for seismically resilient bridges

This paper presents a review of how the ductile diaphragm concept was formulated, evaluated, improved, and implemented over time to achieve seismically resilient bridges. A particular emphasis is placed on the most recent work that has provided a more fully, and more widely applicable, version of the concept. The paper also addresses how to design buckling restrained braces used as energy dissipating elements in the longitudinal direction of multi-span bridges (simple spans or continuous bridges) as part of the ductile diaphragm concept. In all cases, the objective of the ductile diaphragm concept is to concentrate ductility demands in steel energy dissipating elements located at the ends of the superstructure spans to protect the substructure (and rest of the superstructure) from damage, to ensure that the bridge can remain open to full traffic immediately following an earthquake.