Extended-span and alternatively-shaped arch bridge and construction method therefor

A construction method of the large-span and special-shaped arch bridge, wherein the large-span and special-shaped arch bridge comprises a main girder, a center abutment configured to serve as a central bearing point and two auxiliary abutments configured to serve as bearing points at two ends, wherein further comprising an arch-axis combination and two arch-axis bending beams presented as arcs projected upwards, the arch-axis combination being built on the center abutment with two ends connected to the inner ends of the two arch-axis bending beams, the outer ends of the two arch-axis bending beams being built on the two auxiliary abutments, the two arch-axis bending beams being connected to the main girder via a plurality of inhaul cables,

• wherein the arch-axis combination includes a lower arch axis and an upper arch axis, the lower arch axis is presented as a “V” shape and fixed to the center abutment at the bottom of the “V” shape, the upper arch axis is presented as a sunken arc and located in the opening of the “V”-shaped lower arch axis, and the two ends of the upper arch axis are connected to the two ends of the lower arch axis respectively, the method comprising the following steps:
• A, constructs abutments including the center abutment located in the middle and two auxiliary abutments located at both ends of the bridge;
• B, builds the arch-axis combination on the center abutment with segments one by one, and temporarily connects each segment of the arch-axis combination by means of inter-tube positioning;
• C, builds the arch-axis bending beams presented as arcs projected upwards, which includes two sub-steps that can be performed in any particular order:
• C1, butts the segments of each arch-axis bending beams in sequence from the built ends of the arch-axis combination to an end away from the center abutment;
• C2, butts the segments of the arch-axis bending beams in sequence from each auxiliary abutment to an end near the center abutment;
• D, docks the two ends of a closure segments of each arch-axis bending beam respectively with built nodes of each arch-axis bending beam implemented in the sub-steps C1,C2 to perform the closure of each arch-axis bending beam, and welds every adjacent segments of each arch-axis bending beam;
• E, builds girder segments in sequence from the two auxiliary abutments to the center abutment, meanwhile builds the girder segments in sequence from the center abutment to both ends of the bridge, when building the girder segments in sequence from the two auxiliary abutments to the center abutment, connects every built girder segment with the corresponding arch-axis bending beam via cables;
• F, performs the closure of the main girder, and welds the adjacent girder segments.