The Key Of Jacking Construction Of Complex Curved Steel Trough Beam

In recent years,the mileage of China ’s expressways has been rising.With the continuous development of the national transportation network,the number of highway or railway bridge cross-line projects is increasing,and many special bridge lines are also increasing.The difficulty of construction is gradually increasing.However,in the current stage of bridge cross-line construction,the incremental launching construction method is often used in such projects because of its technological advantages of continuous intersection of existing lines.The perfect bridge jacking construction technology has a profound impact on the development of infrastructure in the future.Based on the walking incremental launching construction of Xiangtangpu No.2 Bridge in Hebei Province,combined with the monitoring and finite element simulation of the incremental launching construction site,on the basis of the existing research results,this thesis analyzes and studies the optimization of the guide beam structure,the key problems of construction,the control of construction stress and the scheme of beam falling in the incremental launching construction of complex curve steel channel beam.The main work is as follows :1.Study on the optimal parameters of the variable cross-section guide beam of steel channel beam walking incremental launching construction.Taking the equal-span continuous beam bridge as an example,a simplified calculation model of variable crosssection steel guide beam-main beam is constructed.The equilibrium equation is established by mechanical displacement method,and the expression of bearing bending moment is derived.By setting up a variety of dimensionless parameters and controlling a single variable,the influence of each parameter on the bending moment of the main beam is explored.Scientifically select important parameters such as the length of the variable cross-section guide beam in the actual production,the unit load concentration of the head and tail,the elastic modulus of the material,the moment of inertia of the head and tail sections,and the slope K value.2.Research on key technology of jacking construction of complex curved steel trough beam.The path of jacking construction of steel channel beam and the position of jack are analyzed.Through the construction of various finite element models,the shear optimization of steel pipe support structure is carried out based on the simulation calculation of beam stress and deformation in jacking process.A steel guide beam structure that can be dropped on a 138 ° cushion beam and bracket is designed.By using the optimized main girder synchronous jacking system,the S-shaped main girder is continuously pushed.The safety and reliability of the construction are guaranteed by the measures of the guide beam pier,the temporary locking of the main beam,the lateral rotation and the linear guarantee.3.Research on field monitoring and stress control in incremental launching construction of steel channel beam.By studying the stress characteristics of complex curved steel trough girder,the maximum stress point and structural weakness of the main girder are analyzed,and the on-site monitoring scheme of jacking construction is formulated.According to the actual situation of the site,the geometric monitoring and physical monitoring are combined to monitor the jacking construction of the main girder in real time.Through the comparative analysis of the theoretical value and the measured value,the reliability of the model is verified,the construction safety is guaranteed,and the key construction technologies in the previous paper are verified.4.Comparative analysis of guide beam falling scheme in incremental launching construction of steel trough beam.Through the analysis of the dangerous working conditions in the incremental launching construction,two kinds of guide beam falling schemes are designed.The incremental launching construction model of steel bridge is established by MIDAS / Civil finite element software.The peak stress and maximum deflection of the key section in the incremental launching process are taken as the main reference indexes,and the theoretical values of the two construction falling schemes are compared,so as to determine the optimal guide beam falling scheme and further ensure the safety of cross-line construction.The error between the measured value and the theoretical value is controlled within 15%.