Variable cross-section steel bridge incremental launching construction auxiliary device and construction method

A variable cross-section steel bridge incremental launching construction auxiliary device comprises a plurality of auxiliary units (1) arranged in sequence, the upper ends of the auxiliary units (1) are fixed to the bottom of a variable cross-section steel bridge (7), and the lower ends of the auxiliary units (1) are located on the same horizontal plane. The auxiliary unit (1) comprises a supporting structure and a bottom plate (4); a plurality of sliding grooves are formed in the lower portion of the bottom plate (4), and the arrangement direction of the sliding grooves is in the longitudinaldirection of the variable cross-section steel bridge (7). According to the variable cross-section steel bridge incremental launching construction auxiliary device, the auxiliary units with the variable heights are welded below the variable cross-section steel bridge in advance, so that the bottom of the steel bridge above the sliding rail is in the horizontal plane, and the incremental launchingconstruction difficulty is