Mounting and dismounting method for gantry crane

The invention discloses a method for mounting and dismounting a gantry crane. Before mounting, a main girder and supporting legs are spliced to be an integration on the ground, wherein a supporting leg is connected to anther supporting leg via hinge, a lifting apparatus is arranged on the main girder, the main girder is suspended under two rotating hinges of the two supporting legs, as the supporting legs are gathered, the rotating hinges drives the main girder to lift upwards until reaching a design position, finally connecting rod elements of the supporting legs can be mounted, thereby achieving self-mounting of the portal crane, as the connecting rod elements of the supporting legs are removed, the supporting legs can be released, thereby achieving self-dismounting of the portal crane. The method has the advantages that 1, mounting and dismounting can be achieved on the ground without lifting work in high position, which is safe, convenient and time-saving, 2, less mechanical equipments ...