Spliced and widened bridge connecting device, and construction method and application thereof

The invention discloses a spliced and widened bridge connecting device, and a construction method and application thereof. The spliced and widened bridge connecting device comprises an old bridge flange plate, a new bridge flange plate, a transition butt strap and an asphalt concrete bridge floor; the upper end faces of the new bridge flange plate and the old bridge flange plate are each provided with an abutment opening, and the height of the inner side wall of each abutment opening is smaller than that of the outer side wall of each abutment opening; the new bridge flange plate and the old bridge flange plate are in lap joint through a plurality of transition butt straps, the transition butt straps are arranged in an abutment opening of the new bridge flange plate and an abutment opening of the old bridge flange plate, cushion layers are arranged between the bottoms of the transition butt straps and the bottoms of the abutment openings, gaps are formed between the two sides of the transition butt strap and