Method for installing ultrahigh annular steel tower of cable-stayed bridge

The invention belongs to the field of bridge tower construction, and particularly relates to a cable-stayed bridge ultrahigh annular steel tower mounting method which comprises the following steps: 1, dividing and horizontally placing annular steel tower sections: dividing an annular steel tower into steel tower sections 1-N symmetrically arranged on two sides of a middle pier and a closure section 2N + 1, fixing the first steel tower section with the middle pier, and fixing the second steel tower section with the middle pier; the rest sections are horizontally placed on the jig frames of the main beams on the two sides of the middle pier; 2, mounting steel tower sections 2-N on the right side of the middle pier: mounting inner supporting rods on the inner sides of the steel tower sections, and sequentially pulling the steel tower sections to vertically rotate from top to bottom to be mounted with the next section until 2-N as a whole rotates to be in butt joint with the steel tower section I; thirdly, the se