Research On The Construction Control Technology Of Large Span Continuous Beam Arch Composite Bridge

With the continuous development of bridge construction,it is difficult for continuous girder bridges to meet the high demand of long-span structures,thus developing a continuous beam arch composite bridge.As a combination system,continuous beam arch,which combines the stress characteristics of continuous beam bridge and arch bridge,has the advantages of large stiffness,strong spanning ability,beautiful bridge type and so on.So it is widely used in the construction of railway and highway bridges.As the construction technology of continuous beam and arch composite bridge is complicated and the span has the trend of increasing,it is of practical significance to explore the reasonable construction monitoring technology and method of this kind of composite bridge,which is of great importance to ensure the quality and safety of the construction.This paper is based on a(76+160+76)m continuous beam-arch composite bridge,and the following aspects are mainly studied.(1)The method and control system of bridge alignment control are briefly reviewed.Using the large analysis software Midas Civil to build a full bridge finite element model to simulate the structure,and sensitivity analysis is carried out for different design parameters that may affect the alignment of the main girder at ±20%.The equivalent bulk density of concrete,the equivalent elastic modulus of concrete and the tensile force of steel beam are the three main parameters that affect the line shape of the bridge,which lays a theoretical foundation for the parameter identification based on BP neural network and the prediction of linear deviation in the following line control.(2)Parameter identification and deviation prediction are very important for main beam alignment control.Based on the difference value of pouring and tension difference between three main parameters,the learning samples are set up and trained,and then the measured values are input to get three major parameters which are more practical.The same method is used to predict the camber deviation of the main girder in this paper,and to determine the elevation of the vertical formwork,and finally realize the precise control of the alignment of the main girder.(3)The results of Midas Civil calculation are used to guide the stress monitoring of the main beam and arch rib during the construction of the bridge.Through the comparison and analysis of the measured stress value and the theoretical value,the real time stress state of the structure in the construction process is clearly defined,thus ensuring the construction safety and construction quality,and realizing the stress control of the bridge structure.(4)The identification method of suspender force is introduced.Using the frequency method to identify the force of the suspender in this project.The effective control of the designvalue adjustment of the hanger force is realized.The test calculation shows that the measured value and the design value are less than ±5%,which proves the feasibility and accuracy of the method,and accumulates experience for the adjustment of similar engineering hanger force.This study provides some theoretical support for the construction control technology of continuous beam arch composite bridge.It plays a certain role in promoting the accuracy of construction control,and has good engineering application value.