| In recent years,with the take-off of economy,China has also made great progress in transportation.It is inevitable that bridges need to be built in some existing traffic or complex terrain.If the traditional construction method is adopted,It will not only bring great inconvenience to urban traffic,but also very low construction efficiency.Therefore,the bridge rotation construction method arises at the historic moment,this paper based on the Zoucheng cross-railway overpass project to carry out research.Zoucheng overpass is a single-tower,double-column,double-span and double-cable-plane prestressed concrete cable-stayed bridge with a weight of 22400 t,a length of 2 *99m,a span combination of 2 *110m and a "π" beam with box section on both sides.This bridge is a large-tonnage horizontal cable-stayed bridge with symmetrical structure,which is rarely seen in the world.This paper makes a systematic study of this bridge.The main work and achievements are as follows:First redesign the supporting structure of the rotating system,and optimize the 8 pairs of supporting feet on the original turntable to 6 pairs of supporting feet,so that the force of the rotating structure is reasonable and the rotating process is smooth.After the transformation of the rotating structure system is completed,the whole weight of the rotating body is jointly loaded by spherical hinges and two supporting feet,forming a "three-point force" structure system.Then the traction system is optimized and the original design boost system is replaced by pull system,such as adjusting the number of pre-embedded traction bundles and the tonnage of pull-up jack for reference of large-tonnage turning in the future;then the key parts of the turning structure,such as spherical hinges,slideways,tetrafluoro slides,butter tetrafluoro powder and supporting feet,are defined to ensure the smooth and solid rotation.In order to control the pre-bias within a safe range,the unbalanced weight rotation is adopted.The unbalanced moment,frictional resistance moment and eccentricity of the rotating body are calculated and weighted in the weighing test.The center of the rotating body should be located in the longitudinal axis direction of the beam body and deviated to the North within the range of 5 cm to 10 cm.The weight shows that the eccentricity is the best when the eccentricity is 8.5 cm.Then the unbalance of dead weight,stiffness of bridge structure,wind load and other factors which may affect the swing structure during the swing process are studied to ensure that the bridge before the swing is in the best construction condition.Finally,the finite element software Abaqus is used to calculate and analyze the spherical hinges with different eccentricities,and the stress and displacement curves under different eccentricities are drawn to study the influence of eccentricities on the structure of spherical hinges. |
