Arc-shaped U-shaped steel plate unit for reinforcing arch bridge and construction method thereof

The invention discloses an arc-shaped U-shaped steel plate unit for reinforcing an arch bridge. The arc-shaped U-shaped steel plate unit comprises a plurality of same arc-shaped U-shaped steel plates,and integrally connected flanges are arranged on the two sides of the opening side of the U-shaped steel plate; the U-shaped steel plates are transversely and longitudinally spliced into an arch-shaped supporting body, the arch-shaped supporting body is used for being connected to concrete at the bottom of an arch bridge body, the two sides of the arch-shaped supporting body are connected with one sides of the L-shaped steel plates, and the other sides of the L-shaped steel plates are used for arch feet of the arch bridge body. The structural form of the arch bridge is structurally changed, so that a traditional arch bridge with a planar arch bottom is changed into a two-way curved arch bridge with a good stress state and high bearing capacity; a traditional two-way curved arch bridge ischanged into an integrated