Safety Analysis Of Weight And Support Foot For Two Kinds Of Rotary Joints In T-structure Construction

With the rapid development of China’s infrastructure strength,the level of bridge construction in China is also increasing.Using the horizontal rotation construction method to build bridges across existing lines can minimize the impact on the normal operation of existing line traffic during construction.The construction of cross line bridges will be the development trend of future bridge engineering.Studying the weight balance of different hinge structures of bridges and implementing it in the field is a key step to ensure the safety and stability of the horizontal rotation method for bridge construction.Based on the research background of Taohe Bridge(spherical hinge structure)and Baita Village Pedestrian Overpass(flat hinge structure),this paper elaborates on the weighing test theory of different rotary hinge structures of rotary bridges,and discusses in detail the engineering implementation process of weighing and counterweight for rotary bridges.Taking the supporting feet of Taohe Bridge as an example,the safety analysis of the supporting foot structure is carried out.The following work and research have been done in this article:(1)Using the finite element software Midas · Civil,the modeling and analysis of Taohe Bridge and Baita Village Pedestrian Overpass were conducted,and a comprehensive calculation and analysis of the construction stage was made based on the construction drawings.The vertical displacement,bending moment,and stress values of the main beam in several key construction stages were extracted and summarized,which played a leading role in on-site construction.(2)The principle of ball joint rotation method test is discussed in detail,and a method for selecting and predicting the weighing jack type is proposed.The method is applied to the unbalanced moment test of Taohe Bridge,obtaining the longitudinal unbalanced moment and eccentricity of the bridge,and verifying the accuracy of the weighing method.Subsequently,the advantages and disadvantages of several commonly used testing methods for unbalanced torque of rotating systems in engineering are analyzed,and the accuracy of different testing methods is verified.It is shown that the spherical hinge rotation method is the most accurate method for using spherical hinge structure rotating bridges.Based on the simulation and analysis of different counterweight schemes of Taohe Bridge after the removal of temporary restraints,the vertical deformation and maximum stress changes of the main beam end under different counterweight schemes are determined,and the optimal counterweight scheme is155.6t at a distance of 7.5m from the flat hinge center was the optimal counterweight scheme.(3)The test principle of flat hinge compression method is discussed in detail,and applied in the unbalance moment test of Baita village pedestrian bridge.The longitudinal unbalance moment and eccentricity of bridge are obtained,and the accuracy of weighing method is verified.By comparing the advantages and disadvantages of other testing methods,it is found that the flat-hinged structure rotary bridge uses flat-hinged compression method to achieve the most accurate results.By analyzing different weight schemes of the pedestrian bridge in Baita village,the optimal weight scheme is determined to be 6.4t at the distance of 22.5m and 7.5m of the abnormal hinge center.(4)Taking Taohe Bridge as an example,different specifications are used to calculate the bearing capacity of the unique concrete filled steel tubular leg structure of the swivel bridge,and the stability analysis of the bridge is performed based on its bearing capacity.Establish a finite element model of the support foot to calculate the stress and deformation under the removal of temporary constraints,and the values are within the safe range.Install strain gauges on site to test the stresses after removing temporary restraints and counterweights,rotating at 20 °,rotating at 40 °,and completing the rotation.The values have been within the safe range and have been effectively controlled.This indicates that the safety reserve of such support structures is sufficient,and the support structure itself will not be damaged.