Cantilever Construction Monitoring And Mechanical Analysis Of Rotating Structure Of Box Girder Bridge

In the mountain valley,the depth of the valley is rapid,using the general bridge construction method in the construction will encounter a lot of trouble.Not only is it expensive and the equipment is not easy to use.If the traditional method is used to build bridges across the existing traffic lines,it will greatly interfere with the operation of the existing traffic,which is unacceptable in the current era of heavy traffic.With the continuous improvement of technology and experience,the above-mentioned harm can be avoided and good technical,economic and even social benefits can be obtained by using rotation construction methods such as vertical rotation method or horizontal rotation method.However,in the construction process of rotating bridge,because of the complexity of some of its structures,the rotating bridge will sometimes be difficult to rotate,unable to close up or partial destruction of the rotational structure.Most of the problems and hazards are caused by the lack of deep understanding of the mechanical properties of the rotating structure by the design or construction departments,so it is necessary to carry out scientific research on this problem.Taking the newly built Shanghe-Hangzhou-Nanjing Railway Bridge(60+100+60)m as the research object,the following contents are studied in this paper:(1)the construction process is monitored and analyzed by mechanics.Firstly,the construction process is simulated with Midas Civil software,and the pre-camber and stress simulation values are obtained.The elevation and stress measurements are made at the elevation observation point and the stress measurement point of the bridge.Based on the data,the linear control and stress control of the bridge are carried out.The bridge linetype and force are within the standard range,and the closing error is controlled within the 15mm,which helps the bridge to close smoothly.(2)in order to counteract the eccentricity in the construction process,the paper also makes the weighing test on the bridge in front of the rotating body by using the spherical hinge rotation method,and obtains the difference between the critical jacking force and the displacement of the rotating body test according to the curve of the change of the Jack force and the displacement.Based on this,a series of useful values such as unbalanced moment,eccentricity,friction coefficient and so on are calculated.These parameters not only weigh the rotating body so that the supporting feet are suspended and prevent the instability of the rotating body,but also provide data support for the subsequent trial traction.(3)the stress distribution curve of the rotating body at the spherical hinge is assumed,and the existing calculating method of the maximum stress of the spherical hinge is compared with the contact stress method,and the method of increasing coefficient of bias pressure after edge optimization is compared with that of the existing method of calculating the maximum stress of the spherical hinge.Then the theoretical value is compared with the finite element simulation value calculated by Midas Fea.It is proved that the stress distribution of spherical hinge not only accords with the law of large middle edge,but also is basically coupled with the assumed stress distribution curve.At the same time,it is proved that the maximum stress calculated by the other two methods is more accurate than that calculated by the existing method,and is closer to the simulated value.It provides a basis for a better understanding of the ball hinge force theory.(4)the numerical simulation of force under the center of finite element software shows that there is a linear relationship between deflection and maximum stress of spherical hinge and eccentricity of rotating body,which makes it easier to study the eccentric problem of spherical hinge.