Structure for overturning large-section steel pipe arch rib by gantry crane

The utility model provides a structure for turning over a large-section steel pipe arch rib by gantry cranes, which comprises two gantry cranes, a first lifting point, a second lifting point, a first lifting appliance and a second lifting appliance, the first lifting point is fixedly arranged at one end of each gantry crane, the second lifting point is movably arranged on each gantry crane, the first lifting appliance is arranged on the first lifting point, and the second lifting appliance is arranged on the second lifting point. A second lifting appliance is arranged on the second lifting point; the first lifting appliance comprises a tackle and an annular sling, a shackle is arranged on the sling, the two ends of a steel wire rope are connected through the shackle to form the annular sling, the tackle is rotatably arranged on a lifting hook of a first lifting point, an annular sliding groove is formed in the outer circumferential surface of the tackle, and the sling is arranged on the tackle and an arch rib