Analysis Of Mechanical Properties Of Rotation System Of Asymmetric Rotating Bridge

In order to reduce the impact of new bridges on existing lines,the flat turning construction is widely used in the construction of bridges across lines.The upper and lower ball hinge contact surface of the turning system is free contact,so that the upper and lower bearing platform cannot form a whole,and the turning system bears the weight of the superstructure during the bridge flat turning process and transfers it to the bearing platform pile foundation.The current research on the analysis of the mechanical properties of each component of the rotating system is not consistent and definitive,and it is impossible to form an accurate description of the mechanical properties of the ball hinge.This paper focuses on the construction of large-tonnage turning bridge turning,taking the construction of the new Fuxia high-speed railway Tai Chengxi Special Bridge(94.8+125)m turning with a turning structure weighing 38,000 tons as the engineering background,and conducting local simulation of the turning system.Verify the accuracy by comparing the finite element model with the contact theory;study the upper structure,ballhinged contact and lower structure mechanical characteristics of the rotating system,reveal the upper and lower structure force transfer mechanism,ball-hinged contact surface force distribution law,the influence of pile length and bearing thick Ness on the pile foundation,and the force of bearing pile foundation;Analyze the influence of unbalanced force and eccentric state on the rotating system,and propose optimization suggestions for the local construction of the rotating body and the limitation range for the force balance during the rotating body.This paper conducts the following studies:(1)Based on the main design indexes of the bridge rotation system,the modeling process of contact selection,meshing and load application of the rotation system is introduced,and the finite element model of the whole bridge is established;Based on the ball-hinged contact stress four kinds of ball-hinged contact surface stress calculation theories were selected for comparative analysis,and the above theories were compared and analyzed with the measured values,and it was found that the results of the engineering simplex method,halfplane body and half-space body subjected to uniform load algorithm are vertical average contact stress,all smaller than the measured values,mainly due to the measured values of radial stress are larger than the vertical stress.(2)The study of solid pier,hollow pier,double-supported thin-walled pier three pier body form on the rotating system in the process of rotation of the upper turntable contact parts of the force impact and force transfer mode,found that in the rotating conditions of solid pier bottom generated the smallest main tensile stress,increase the solid section of the pier bottom can significantly reduce the maximum main tensile stress of the hollow pier and doublesupported thin-walled pier bottom;To study the effect of the radius of the spherical surface of the spherical hinge on the forces in the rotating system.An increase in the radius of the spherical surface increases the maximum equivalent force at the contact surface of the spherical hinge and increases the average stress,while the equivalent forces at the contact surface of the spherical hinge tend to average out;The effect of bearing thick Ness and pile length on the force characteristics of the rotating system is studied.The force on the rotating pile foundation is large in the middle and small at the edge,and increasing the thick Ness and length of the pile foundation can significantly improve the reasonableness of the force.(3)By establishing two models of rotating systems with and without locating pins,it is found that locating pins can effectively resist the traction unbalance force,and the critical value of the unbalance force is derived from the connection between the locating pin resistance and the unbalance force to study the influence of asymmetric traction force on the rotating system;To introduce the balance weighing test before the construction of large-tonnage asymmetric bridges turning in conjunction with this project,and to calculate the counterweight results based on the weighing test;The unbalance moment is derived from the weighing test,and the effect of the unbalance moment on the rotating system is studied.The anti-slip stability coefficient λis established,and when λ is greater than 1,the beam is in a stable state,and when λ is less than1,the beam is in a destabilized state,and the critical value of the unbalance moment that the rotating bridge can withstand is predicted by the anti-slip stability coefficient.