Research On Key Technology Of Construction Monitoring Of Middle-through Steel Truss Arch Bridge

Steel truss arch bridge is widely used in practical engineering because of its advantages of high bearing capacity,strong span capacity and unique and beautiful shape.This kind of bridge belongs to multiple statically indeterminate structure,the determination of reasonable bridge state and system transformation in the construction process have always been the key problems in its research.Combined with the actual project,this paper carries out relevant research on the reasonable forming state,system transformation and parameter sensitivity of steel truss arch bridge.The main contents include:(1)Study on reasonable bridge formation state of steel truss arch bridge.In this paper,the principle of reasonable bridge state of steel truss arch bridge is determined,and the corresponding bridge state of rigid support continuous beam method,rigid suspender method and minimum bending energy method are co MPared and analyzed.On this basis,the comprehensive algorithm of reasonable bridge state determination of steel truss arch bridge is put forward,and has been applied in real bridge.(2)Study on transformation of steel truss arch bridge system.First determine the principle of system transformation,and puts forward different tensioning schemes,and the co MParative analysis of different tensioning schemes in the process of tensioning structure internal force and deformation of the situation,on this basis to determine a kind of both accuracy and efficiency of the "two stage" tensioning schemes,namely the tension in the early stage and the second stage dead load target before tensioning stage.In the initial stage of tension,on the one hand,the structure can be changed into the system force,on the other hand,the change of cable force and internal force in the process of tension can be avoided.In the second stage,the cable force of the completed bridge can be avoided by realizing the two-constant pre-target cable force.The concrete realization process is as follows: in the initial tension stage,from arch foot to mid-span tension to 60% of the two-constant front target cable force of the boom,realizing the force of the system;In the second stage,the system is transformed from arch foot to mid-span tensioning to100% of the two-constant front target cable force of the boom.(3)Midas Civil,a finite element software,is used to analyze the stress of the bridge in the construction stage in combination with the tensioning scheme,and the stress and deformation of the main structure of the bridge in the construction process are clarified.Midas FEA finite element software is used to analyze the stress of complex arch foot and determine the stress condition under the most unfavorable construction condition.(4)Sensitivity analysis of construction control parameters.The sensitivity analysis of hanger rod tension,temperature and UHPC thick Ness is carried out.After the parameters change a certain range,the displacement of the structure control part and the size of internal force change range caused by this are analyzed.According to the sensitivity of each parameter to the structure state,the design parameters are divided into main design parameters and secondary design parameters,and the main design parameters are considered in the construction control process to ensure that the bridge state meets the design requirements.(5)The stress and deformation of the derrick cable force and the main section of the bridge in the construction process are monitored,and the measured value on site is co MPared with the theoretical calculation value.On this basis,the main sources of error are analyzed,and the results can provide reference for the design and construction of similar Bridges in the future.