This study describes a new
technique for
strengthening an existing continuous reinforced concrete Gerber
bridge
by using external prestressing tendons, which benefits from requiring
minimum traffic disruption. The external tendons are used to reduce the excess
live shear load at the Gerber hinge by lifting cantilever girder up, not to
introduce compressive stress into the girder such as ordinary external
prestressing methods. In this paper, the following are presented: (1) the
principle of this
strengthening system, (2) outline of strengthening work for
the
existing bridge carried out by this system, and (3) test results executed
simultaneously with on-site construction for confirmation of the effects of
this system.