1. A reinforcement apparatus for reinforcing a structure, the structure comprising at least one pier bearing on foundations, a cross-beam bearing on the pier and at least one structure element located above the cross-beam, the reinforcement apparatus comprising:at least one column to surround the pier at least partly, to be mechanically coupled to the pier and to bear on the foundations; and
at least one transverse beam fixed relative to the column and to be mechanically coupled to the cross-beam,
wherein the at least one column comprises two column faces facing the pier and respectively located on opposite sides of the pier, each column face and the pier defining a gap therebetween, each gap being at least partly filled with a reinforcing material, and
wherein the at least one column further comprises a casing surrounding the pier at least partly, the casing being made of the reinforcing material at least in part.