Research On Key Technology Of Construction Control Of Long-span Stiffened Steel Truss Continuous Rigid Frame Bridge

As a new type of bridge structure,the stiffened steel truss continuous rigid frame bridge can not only improve the overall rigidity of the bridge,but also effectively solve the problems of midspan deflection and beam cracking existing in the traditional continuous rigid frame bridge.In this thesis,the construction control,parameter analysis and bridge closure optimization are carried out based on the project of No.2 Moguhe Extra-large Bridge in Yinxi railway.The main work is as follows:(1)This paper introduces the development history of different forms of steel truss-concrete composite structures,and summarizes the development and application of bridge construction control technology at home and abroad.(2)This finite element software Midas Civil is used to establish the calculation model of the whole bridge construction process,and the displacement and stress in each construction stage of the bridge were analyzed,which laid a theoretical foundation for the subsequent actual construction control.(3)The influences of concrete material parameters,prestress loss parameters and temperature changes on the bridge alignment and internal force are analyzed,and relevant correction suggestions are put forward.Through the analysis of the temperature effect of the bridge after closure,the suitable splicing temperature of stiffened steel truss is put forward to be 5~15?.(4)A reasonable construction control plan is developed for the bridge,and the measured data in the construction process is analyzed and compared with the theoretical data.The results show that the bridge line shape and stress are well controlled,which meet the design requirements,and the main causes of the errors in the construction control are analyzed.(5)There is a deviation between the actual closure temperature and the design closure temperature of the bridge.Using the finite element software,the jacking displacement and thrust are optimized.The jacking force of the bridge at 5? closure is determined to be 7300 kN,The results of the bridge closure show that the jacking force calculated by the finite element method is more accurate;A local solid model of the stiffened steel truss and concrete main beam is established through Midas FEA,the stress concentration phenomenon of the steel-concrete connection was analyzed,and the corresponding control measures are put forward.