FIG. 1. Inelastic Behavior of Ductile End-Diaphragms Com- pared with Existing Strong Diaphragms

A seismic retrofit strategy that relies instead on ductile end-diaphragms inserted in the steel superstructure, if effective, could provide an interesting alternative. In some cases, by re-placing the steel diaphragms over abutments and piers with specially designed ductile diaphragms calibrated to yield be-fore the strength of the substructure is reached, damage can be prevented from developing in the nonductile substructura