Method and structural system for improving three-direction stress performance of large-span three-tower cable-stayed bridge

The invention discloses a method and a structural system for improving the three-direction stress performance of a large-span three-tower cable-stayed bridge. The method comprises the steps that the vertical rigidity of the three-tower cable-stayed bridge is improved through auxiliary cables and longitudinal elastic inhaul cables on the two sides of a middle tower; the three-tower cable-stayed bridge is subjected to three-stage control of longitudinal static and dynamic response under the temperature load effect, the working condition of the most unfavorable static load and the working condition of the earthquake effect through the longitudinal elastic inhaul cable between the middle tower and the main beam and the longitudinal viscous dampers on the first side tower and the second side tower. The transverse static and dynamic response of the large-span three-tower cable-stayed bridge tower is subjected to three-stage control through the novel damping, energy-consuming and wind-resistant supports among the mi