Static And Dynamic Analysis And Construction Monitoring Study On The Steel Box Tied Arch Bridge With Beams First And Back Arch

The influence of the symmetrical layout of the bridge superstructure on the dynamic and static behavior of the structure,and the completion of construction monitoring and cable force adjustment of the bridge are all issues that bridge workers are very concerned about.This paper takes the steel box tied arch bridge under construction in HengYang as the engineering background,and establishes a full bridge model according to the layout characteristics of its superstructure,carries out dynamic and static analysis and elastic analysis,and makes a key analysis of the construction monitoring and the completion of the bridge The selection and comparison of cable force adjustment and the adjustment of cable force program make a reasonable analysis,which provides an important theoretical basis and engineering experience for rebuilding similar projects in the future.The main research contents of this article are as follows:(1)Using Midas/civil to build a full bridge model and do static analysis on it,the internal force and displacement distribution of the bridge model under five working conditions are obtained.The results show that the arch ribs are under full-section compression,and the stress on each part of the tie beam is relatively small and uniform,all within the specified allowable range;the constant load has the greatest influence on the internal force of the structure,which can account for 70%of the total effect of the combined load%～80%;the symmetrical layout of the bridge superstructure has no effect on the force distribution of the structure,the displacement on the left and right sides is basically the same,and the linear shape is basically not affected.(2)Using Midas/civil to do a dynamic analysis of the full bridge model and study its dynamic characteristics,the results show that:in the natural vibration response of the bridge,the vibration deformation of the arch rib is the largest,and its lateral stiffness and stability are the worst,compared with the steel pipe The concrete arch ribs have poor lateral stiffness and stability because of lack of cross braces.The vertical cumulative vibration mode participation mass is the smallest at 97.08%;the vertical overall rigidity is the largest,the lateral overall rigidity is the smallest,and the longitudinal overall rigidity is centered;at the same time,the bridge structure is symmetrically arranged,which has no effect on the dynamic response of the bridge.(3)The theoretical analysis data is used to guide the dynamic load test after the bridge is completed.The measured data of the dynamic load test is compared with the theoretical data of the model analysis.The results are in good agreement,indicating that the dynamic characteristics analysis has reached an ideal state.(4)The Midas/civil software was used to establish the finite element model of the full bridge during the construction phase,and the formal analysis method was used to simulate the entire construction process to obtain the displacement and internal force changes of the key sections of the bridge and arch ribs during the construction process.Based on the calculation results and the bridge construction plan,on-site data collection and monitoring were carried out on the entire process of the construction of the steel box tied arch bridge.The stress and deformation monitoring values of each control section collected on site were compared with the theoretical calculation results.The results showed that:two The data are in good agreement with each other,and the construction process is carried out safely within a controllable range,which can ensure the safety and reliability of bridge construction.(5)A series of theoretical analysis and calculations were carried out on the full bridge suspender cable force adjustment cable,and combined with the actual project,the influence matrix method was used to calculate the suspender cable force value to be adjusted,and three different numbers of cable adjustment programs were carried out.For comparative analysis,with the cable force of the bridge as the control goal,the optimal solution is determined with the smallest number of cables.The optimal cable adjustment scheme was selected through the comparison of cable adjustment schemes.The number of cable adjustments was reduced from the original 28 to 16,reducing the amount of adjustment work required,and finally realizing the adjustment of the suspender cable force value and design cable of the real bridge.The deviation rate of the force value is controlled within 5%to achieve the ideal cable force state of the bridge.The research results of this paper have been applied to the design and construction of the Zhengtan Bridge.The bridge has been opened to traffic and is in good operation.The research results of this paper have certain reference significance for the design and construction of similar bridge types in the future.