This paper describes a fabrication and construction of extremely long buckling-restrained braces (BRBs) which have been developed for seismic retrofit of a steel bridge. In order to both improve constructional process and reduce deformation by its own weight, it is devised to lighten the BRB. And the parallel structural system of BRBs is applied for the purpose of safety under construction. The structural details are determined based on the knowledge obtained by tests and analysis. Furthermore, waterproofing for rust prevention, monitoring conditions inside of the BRB, and recording deformation of the BRB under large earthquake are proposed and applied to the system.
