Development On A Project-level Bridge Management System And Study On Some Relative Problems

Highway transportation is a necessary condition for the rapid development of social economy. The bridge is an important part in a highway. Performance of the bridge not only effects transportation operation and driving safety, but also has great impact on socioeconomic benefit in the society. In recent years, with a rapid growing of traffic flow, a continuously increasing of heavy truck proportion and frequent occurrences of vehicle overloading, load bearing of the highway bridges have been faced with great challenge. Additionally bridge management level can not keep up with the changing management requirement, quite a few bridge collapse events caused by inadequate maintenance and overloading have been reported in our country. Guangzhou North-Ring Highway is one of the earliest built and operated highways in China. It also is one of the highways that carry the maximum traffic flow and heavy trucks. The serious damages of bridges along this highway lead to serious threat of driving safety. To meet the request of the Guangzhou North-Ring Highway company, a project-level bridge management system——North-Ring Highway Bridge Management System (NBMS) is developed by Research Center of Urban Habitat and Infrastructure Development of South China University of Technology. This system provides routine maintenance of the highway bridges with effective information and technical support.The work of this paper is based on the research and development of NBMS. Although NBMS has realized the powerful information management function, its functions of performance assessment and prediction as well as the decision-making are still on the initial stage, just as other bridge management systems in China. According to the characteristics of North-Ring bridge management and the practice of NBMS, in this thesis three research topics are chosen. One topic is the inspection and assessment of the bridge vehicle load and load effect, which is a foundation of bridge bearing capacity and safety estimation. The second topic is trying to develop an optimization analysis model for inspection and repair decision-making, which explores an approach for inspection and repair decision-making in Bridge Management System. The last topic is proposing an analysis method of bridge composite life based on bridge performance, which provides a new theory idea for life analysis in bridge maintenance decision-making.The safety analysis of bridges under heavy truck action is very important. In this paper, a total probability method is used for analyzing the vehicle load on North-Ring highway and the load effect of bridge caused by vehicle loads. Firstly, the vehicle axle loads and wheelbases on North-Ring Highway are collected and measured. The vehicle type and weight on this highway section are statistically analyzed in terms of the measured samples. Then, the conditions of vehicle overload and uniaxail overrun on North-Ring Highway are analyzed, and the data of vehicle flow and monthly vehicle type on this load section are also analyzed. Secondly, extreme value methods are introduced. Base on the collected vehicle samples, these extreme value methods and the current method are analyzed and compared to indicate that the current method undervalues the extreme value of vehicle loads to a certain extent. Meanwhile, the suitable extreme value statistic models for vehicle loads are suggested. Finally, the total probability method is used to simulate the actual flow, and the corresponding formula for estimating generalized fleet flow is proposed. Combining with the selected extreme value statistic models, i.e., the threshold model and the point process model, a relatively systematic model for vehicle load effect estimation is developed. And the load effect of the bridge is predicted based on the fleet flow derived from the traffic flow in different analysis periods. A comparison of the generated results from the proposed estimation model and from the Code of'Specification for Inspection and Evaluation of Load-bearing Capacity of Highway Bridge'shows that the estimation result of bridge safety considering actual vehicle load is lower than that from the design load. Therefore, an accurate estimation of actual vehicle load is the foundation of bridge safety assessment.Inspection and repair are two important steps in bridge management. The cost and benefit of different repair strategies has great difference. In order to reduce the repair cost with the permission of bridge performance, adequate and reliable bridge information is needed. And inspection is an important way to obtain bridge information. However, the inspection information is nothing but some samples of bridge total information, the repair decision-making made by such samples may result in an unreasonable result. In this paper, a decision-making model for bridge inspection and repair based on benefit maximization is developed with Bayes analysis method. This inspection and repair decision-making model is not only suitable for bridge members but also for the whole bridge. Furthermore, the model combines prior information with inspection information to provide more sufficient data to support the decision-making.Life analysis has great significance in bridge maintenance manangement. Determination of bridge remaining life is a complex optimization problem. In order to simplify the optimization process, how to consider bridge performances and cost in life analysis is worth discussing. According to the equipment renewing profit rate, the bridge structure maintenance profit rate is defined by analogy, and a formula of economy index is proposed. Then the analysis method for bridge composite life considering various performances is built. In this method, the combination of safety index, condition index and economy index in life analysis simplifies the optimization analysis of life circle in bridge maintenance decision-making.