Reliability Analysis Of Reconstructed Bridge

There are many old highway bridges in China.Due to various diseases in long-term service,the normal use of bridges is threatened.For the damage detection of old bridges,a corresponding bridge reconstruction plan is made based on the detection results.The fatigue design check and reliability assessment of the bridge according to the reconstruction plan can improve the service life of the bridge and provide a reference for later operation and use.Relying on the reconstruction project of Shaoxing Hushang Bridge,this paper examines and designs it,and checks and studies the reliability of the reconstructed bridge based on the reliability theory's partial coefficient of resistance,and the main contents are as follows:(1)The various parts that make up the bridge structure were tested and the disease conditions were statistically classified.Select the evaluation method applicable to the bridge from the commonly used technical evaluation methods of bridge structures,and calculate the parts of the bridge based on the test results according to the bridge specification scores;analyze the overall technical status of the bridge by determining the technical status scores of each part to determine Technical status of the overall condition of the bridge.(2)According to the results of disease detection,a reasonable transformation scheme was designed.According to the provisions of the general specification for highway bridge and culvert design(JTG D60-2015)and the design specification for highway reinforced concrete and prestressed concrete culverts(JTG D62-2004),MIDAS software was used to analyze the structural load combination safety of bridge panels.According to the general specification for highway bridge and culvert design,the load combination stress of steel girder is analyzed.The results show that the steel composite beam is the optimal scheme for superstructure replacement,and each index has at least 70%redundancy relative to the specification limit.(3)The ABAQUS finite element software is used to simulate the reconstructed full bridge.The analysis is based on the different conditions of the lane load and vehicle load in the code,and the key monitoring points and issues to be paid attention to when the bridge is put into operation.The results show that according to the direction of the lane,the seventh and third spans and the steel beam in the middle of the cross section are the key monitoring sites,and the restrictions on traffic flow should be paid attention to avoid traffic jams and excessive transportation of heavy vehicles.(4)Based on the reliability theory,the partial resistance coefficient should be taken when the design is based on the fatigue design method 2 in the Code for Design of Highway Steel Structure Bridges.By assuming that the stress amplitude obeys the Rayleigh distribution,the relationship between the fatigue resistance partial coefficient and the bridge design parameters is obtained.Based on the actual vehicle load statistics in Shaoxing area,calculate the statistical value of the stress amplitude generated by the vehicle through the bridge,combined with the bridge design parameters,and substituted into the relationship formula for the resistance partial coefficient in the code.The value of the resistance partial coefficient was obtained and analyzed.It varies with vehicle weight,bridge design life,reliability index,and bridge span.(5)Introduce the basic structure system,simplify the complex bridge structure,conduct reliability research on the modified bridge from the aspect of safety,determine the evaluation model and method by using the analytic hierarchy process,combine the assessment of the technical condition of the bridge,and reconstruct the actual bridge based on the reliability The project performs reliability assessment and research,and analyzes the influence of the combination of new and old bridges on the entire bridge and the reliability of the bridge system after the transformation.