Research On Mechanical Properties Of Prestressed Concrete Continuous Girder Bridge Based On Load Test Before And After Reinforcement

With the rapid development of China's highway and bridge construction,the form of bridge structure has become more diverse.However,for municipal bridges,medium and small span highway bridges,etc.,reinforced concrete or prestressed concrete girder bridges are still the main ones.The main reason is that this type of bridge is characterized by strong adaptability,convenient material selection and standardized construction.Among them,the small box girder has the advantages of large torsion resistance,bending rigidity,good integrity and reasonable force,which can meet the requirements of smooth and comfortable driving,and has low price and short construction period.It has been rapidly developed and widely used.This paper relies on the research work and achievements of the Qixing II Bridge in Sinan-Zunyi Expressway in Guizhou Province,which is aimed at the defects,reinforcement methods and effects of prestressed continuous small box girder bridges.The following achievements are included:(1)Through checking the status of Qixing II Bridge on Sinan-Zunyi Expressway in Guizhou Province and collecting the basic data(geometric parameters and material parameters)of the bridge,the defects of the small box girder bridge construction are identified,and the overall quality of the bridge is evaluated.(2)According to the results of bridge appearance inspection,the causes of defects of the small box girder bridge construction are analyzed.The influence of existing diseases and defects on bridge bearing capacity is studied by theoretical analysis and qualitative analysis,and the attributes of defects are evaluated.(3)Based on the the characteristics of defects of bridges,a finite element model is established to study the transverse distribution characteristics of box girders under multi-load test conditions.Simplified calculation model,spatial calculation model(girder lattice model)and real bridge load test model are used to conduct theoretical research,and the actual mechanical performance,structural bearing capacity and normal service performance of bridges are evaluated synthetically with the actual bridge test results.The overall mechanical performance of the bridge is analyzed,and whether the bridge can meet the requirements of design and service is evaluated.Based on the detection and reinforcement project of Qixing II Bridge in Guizhou,the bearing capacity verification and working condition evaluation are carried out,which provides technical support for the reinforcement decision-making and later operation management of Qixing II Bridge.Through the analysis and study of the reinforcement effect of external prestressing and bonding CFRP plates,the optimum reinforcement scheme for small concrete box girder bridge is obtained.Based on the assessment results of bridge technical conditions and load test results,the treatment schemes and measures for bridge diseases are put forward,which can provide technical support for engineering application and provide reference for the reinforcement of other similar bridges.