Construction Control Of Large Tonnage Bidirectional Unbalanced Rotary Body And Parameter Analysis Of RPC Combined Ball Hinge

As a unique bridge construction method across complex terrain conditions,swivel construction is widely used in China.For the bridge construction across the railway overpass,the swivel construction is undoubtedly the most effective and the least influential construction method.For the large tonnage,large cantilever,wide span unbalanced swivel T-shaped bridge,the technical difficulty is greater,the technical accuracy is higher,and the complex process of unbalanced counterweight during the swivel construction is an important problem to be solved in the swivel construction.Based on the project of Yumenkou highway bridge west approach of national highway 108,this paper studies the technology of turning construction.On the basis of weighing test,combined with finite element model analysis and calculation,the unbalanced construction and counterweight of T-structure are studied,the mechanical performance and construction control of main beam and local zero block in the construction process are studied,and RPC(reactive powder)is studied The mechanical properties and static friction coefficient calculation theory of concrete composite spherical hinge are systematically studied.The method of contact stress fitting curve is proposed to calculate the static friction coefficient of spherical hinge.The main contents are as follows:(1)Through the collection of data and similar engineering construction weighing methods,the existing experience is summarized,and through the establishment of a finite element model to verify and discuss its rationality.Then,the unbalanced moment model of the bridge is established to simulate different kinds of weighing and counterweight methods,and the appropriate weighing and counterweight scheme for the project is proposed.Through field measurement,the unbalanced moment,friction coefficient and eccentricity are determined,compared with the theoretical model,and the model parameters are modified to keep the same state.According to the updated model parameters,the counterweight scheme is revised again,the counterweight scheme of swivel beam is completed,the weight and position of counterweight are determined,and after the completion of swivel construction,all weighing and counterweight data of each stage are collected,and then a set of weighing and counterweight method suitable for the swivel type is obtained.(2)Research on the monitoring of rotary construction of supporting projects.Establish the finite element model of the whole bridge,calculate the stress and deformation of the control section,and predict the elevation of the control points in each construction stage.By comparing the predicted results with the field measured data,the predicted data can be fine tuned to reduce the error,which can better guide the construction.(3)This paper studies the mechanical performance of the main beam and the local structure block 0 in the process of the cantilever casting construction,establishes the T-frame beam element model and the Block 0 entity finite element model respectively,considers the actual load state,carries on the real-time revision to the model,and monitors the mechanical performance of the main beam in combination with the on-site monitoring system,guarantees the construction safety,and finally obtains a set of suitable for the swivel construction process The calculation method and monitoring system in can provide reference for similar bridge construction calculation and control.(4)The nonlinear finite element method is used to analyze the stress state of RPC spherical joints,and various theoretical calculation methods for static friction coefficient of spherical joints are collected and summarized.A new mathematical model for calculating the friction moment of spherical hinge is established,and the formulas for calculating the friction moment and static friction coefficient of spherical hinge are derived.Compare the static friction coefficient of conventional formula and new formula in weighing test,compare the deviation between the static friction coefficient calculated by conventional formula and that calculated by actual traction backstepping,check whether the static friction coefficient calculated by the new formula is consistent with that calculated by actual traction backstepping,so as to verify the accuracy of the new formula.