Midspan closure method of steel structure cable-stayed bridge

The invention discloses a mid-span closure method of a steel structure cable-stayed bridge in the field of bridge construction. The mid-span closure method comprises the steps that a pre-adjustment value delta adjustment of a 0 # steel beam is calculated based on the design length L < set >, the operation space L < operation >, the unstressed length l of each steel beam, the variable quantity l < temperature > and the compression quantity l < compression >; the installation position of the 0 # section steel beam is adjusted according to the pre-adjustment value delta with the center line of the main tower as the reference; other steel beams are built along the two sides of the 0 # steel beam, the unbalanced force of the horizontal component force of the inhaul cables borne by the steel beams is controlled to move towards the midspan direction and is smaller than the sum of the friction resistance borne by the steel beams, and a closure opening is formed between the two main towers; a closure section steel bea