Large-span steel truss bridge strengthening structure

The utility model discloses a large-span steel truss bridge strengthening structure, which is characterized in that each lower chord is integrally of a trapezoidal structure and comprises a horizontally arranged top chord and inclined waist chords positioned at two ends of the top chord, longitudinal beams are arranged between the two lower chords in parallel, and the longitudinal beams are connected with the lower chords on two sides through cross beams; the free ends of the waist chord members extend out of bearing parts in the horizontal direction, the top chord members in the middle of the bridge body serve as main supports, pressure borne by the top chord members is transmitted to the bridge piers supporting the bridge body through the waist chord members at the two ends, part of the pressure borne by the waist chord members is transmitted to the bridge piers supporting the bridge body, and the other part of the pressure borne by the waist chord members forms extrusion force on the top chord members. Aft