Maintenance Strategy Of Concrete Girder Bridges Based On Life Cycle

Safe operation after the concrete girder bridge been complete has become a major issue related to the benefit for the people's livelihood,while the establishment of the concrete girder bridge maintenance strategy system can assist the bridge authorities to assess the technical condition of the bridge and make the appropriate maintenance strategy after bridge detection,thus greatly improve the maintenance efficiency and save maintenance costs.Therefore,the establishment of life cycle concrete girder bridge maintenance strategy system possess a significant economic and social importance.This thesis takes the highway concrete girder bridge in-service from Fujian Province as a project background.A software system which is suitable for the evaluation of the technical condition and formulation of the maintenance strategy in the life cycle of concrete girder bridge is developed with referencing bridge inspection and maintenance standards at home and abroad.This thesis also optimizes the maintenance time and method in life cycle for concrete girder bridge.The main research work and conclusions are as follows:(1)The typical disease phenomenon of the coastal concrete girder bridges in Fujian province are analyzed base on the spot investigation.The results of the investigation with 81 coastal concrete bridges show that the most common diseases phenomenon include reinforced concrete bridge deck pavement disease,upper bearing component disease and bridge pier disease,probability of pier reinforcement corrosion in seawater immersion is higher than girder in atmosphere to 1?2 grades,rate of pier reinforcement corrosion in seawater immersion is the same or higher as the girder in atmosphere,the carbonation depth of girder in atmosphere is 1.5 times or more as much as the pier in seawater immersion.The database of disease and maintenance measures of concrete beam bridge was built based on the investigation results.(2)The reference table of the five level classification of components and the score reference table of distress condition(bearing capacity,traffic capacity,technical condition of the bridge were defined by using the method of combining qualitative and quantitative analysis for the purpose of quantify the damage and maintenance effect of concrete girder bridge.Basing on the Fuzzy Mathematics,Analytic Hierarchy Process(AHP),Membership Function to establish the bridge evaluation system.The distress condition(bearing capacity,traffic capacity,technical condition of the bridge)is predicted by the methods of Grey System and Markov Chain Theory.And also the bridge project and network level decision was made by Decision Tree and Multiple Attribute Decision Making method(MADM).(3)Developing Fujian maintenance information system software(FJ-MIS)of concrete girder bridge based on life cycle by Graphical User Interface(GUI)and C++ compiler.This software consists of basic data module,evaluation module,life cycle cost analysis module,expert knowledge module,future state prediction module,priority selection module and result output module.Using the software to carry out the case analysis shows that the cost of bridge maintenance is the same as construction period cost and sometimes far higher than construction period cost.(4)The concrete bridge maintenance strategy is divided into preventive maintenance(PM)and corrective maintenance(CM).Life cycle maintenance cost is the objective of optimization and using Matlab genetic algorithm toolbox to study optimization maintenance strategy of concrete girder bridge.The Dong Dai Bridge is the project background of optimization analysis.Optimization results shows the best maintenance time and maintenance method of girder and pier of Dong Dai Bridge in the whole life cycle.The optimization results show that under the constraints of bridge service time and the minimum performance Dong Dai bridge life cycle maintenance cost is the sort of PM+ CM<CM.