Study On Swivel Construction Control And Stability For Large Tonnage Continuous Rigid Frame Bridge

The bridge swivel construction has many advantages, and can well meet the needs of the development of modern transport technology. However, the different swivel bridge has the different rotating construction control method and the mechanical properties. This paper based on a certain(68+116+68) m continuous rigid frame bridge with swivel as the engineering background, parameters which effect the alignment of main girder and internal force of this bridge and the stability of this swivel bridges were studied. The main research work is as follows:(1)To establish the finite element model of the bridge with Midas Civil finite element software, pre-camber value of main girder is calculated and extracted under two kinds of construction sequence with Installation shelter before or after the closure. Analyse the influence of installation sequence of shelter on the shape of main beam, and determine the optimal construction sequence with the actual situation. The sensitivity of the parameters including concrete density, prestressed tension, elastic modulus, unilateral overweight and closure time which effect the alignment of main girder and internal force was analyzed in detail. The results show that the weight of concrete and the tensile force of the prestressed tension have a significant influence on the construction precision of the bridge. The change of parameter value should be strictly controlled during construction to ensure that the alignment and internal force of the bridge are in conformity with the design values.(2)Take a certain(40+64+40) m swivel bridge as an example, the weighting test of the bridge was carried out by using the ball-hinge rotation method, through the field test and test data analysis provides a reasonable weighing test scheme for the continuous rigid structure bridge with(68+116+68) m. Through the analysis of field data, each test pier reaching the critical load values with few times of top force loading series in the first weighing. This finding provides a valuable experience for top loading series control of swivel bridge test pier in the first weighing.(3)Considering wind load and unbalanced weight, calculate the safety stability coefficient of bridge under different ball hinge friction coefficient by analytic method when the bridge is static or swiveling. The safety stability coefficient of the bridge is very high under the action of wind load, while the unbalanced weight has a great influence on the safety and stability of the bridge. Through the comparative analysis of safety factor of swivel bridge under different ball hinge friction coefficient, a method is proposed to determine the weight of the rotation scheme based on the static friction coefficient values measured in the field weighing test to ensure the safety and stability of vertical swivel bridge.(4)To establish the finite element model of the rotation system of the bridge by ANSYS software, calculate the local stress of the upper spherical hinge, the lower spherical hinge and the lower bearing platform concrete and foot support displacement only under the action of gravity,and stress at the connection of main girder, bridge pier and main girder when the rotation speed of swivel bridge is constant. Under the self weight, the stress values of each member can meet the requirements of the specification.While the different rotation speed has less influence on the stress of the main beam, the bridge pier and the main girder.