Abstract: The load bearing capacity of girders, particularly those already installed in bridges, may be increased by providing, on each face of the girder, an external reinforcement which comprises a tension member divided into three stretches, namely a first stretch extending downwardly from the upper corner of the web adjacent the upper flange at one end of the girder and a first point of the lower edge of the lower flange of the girder at a predetermined distance from said one end a second stretch extending horizontally from said first point to a second point of the lower edge of the lower flange of the girder at a predetermined distance from the opposite end of the girder, and a third stretch extending upwardly from said second point to the upper corner of the web adjacent the upper flange at the opposite end of the girder, connecting the ends of said tension member stretches exclusively by means of friction forces to the girder, and either simultaneously or independently tensing said tension member stretches in or