Ductile end diaphragms have been suggested as an appropriate device in the past to improve the seismic response of steel girder bridges. This paper investigates the efficiency of the seismic design strategy that utilized a slab-connected steel plate as a ductile diaphragm in the superstructure. Protecting the main girder from typically reported damage and mitigating the transferred lateral load to the non-ductile substructures are the main objectives of this study. The results show that a slab-connected thin steel plate with low yielding stress (LYS) can miti-gate the force demand on the non-ductile substructures and act as a structural fuse. It can also reduce the transverse displacement of the superstructure and, consequently, prevent the end of the main girder from buckling and/or yielding.