Study On Assessment Of Bridge Safety Based On The Monitoring Data

To guarantee the safety of bridge structure, it is essential to control, monitor and assess the safety of biridge structure at different stages. Firstly, during bridge construction, it is necessary to inspect and control the bridge construction throughout the the whole course to ensure the safe condition of structure in different stages, and the line shape and stress condition after the completion. Secondly, for the newly constructed bridges, it is essential to verify the construction quality and build the baseline finite element model for later damage identification and health monitoring through the test for open to traffic. In the end, for existing bridge, it is also necessary to monitor the real-time overall behavior of bridge, aquire the information that reflects the structure condition through measure its Key Performance Indicators and assess its health condition.Though many research works are carried out home and abroad, and there are many process methods and research findings about bridge safety assessment, many key problems or difficulties have not been solved, such as there is few research results for the long-span high-pier continuous rigid frame bridge in cold regions.. Based on the research background and sponsored by supported by a grant from National Science Fund for Distinguished Young Scholars (No.50925828),combined with the engineering practices of Xiaoshawan Huanghe Super Major Bridge, this dissertation aims to study a few key techniques of the assessment of bridge safety from the construction phase to the actual operational phase, control and monitor the bridge safety, gurantee its condition all the time, the construction control for long-span bridge, the setup of baseline finite element model long-span bridge and health monitoring for long-span bridge are mainly investigated. The results of the dissertation can be used in the practice of bridge structures for construction control, damage identification, health monitoring and bearing capacity evaluation and the application is significant theoretically and practically.In this dissertation, following aspects are studied theoretically, numerically and experimentally, and some results are achieved:(1) The construction control is carried through successfully for Xiaoshawan Huanghe Super Major Bridge. The aim, principle and method of construction control are introduced, and the implementation plan is set up. The the construction process are controlled all the time. From the results of line shape and stress, it can be seen that the quality of superstructure meets the requirements of codes, and the errors of internal force and ling shape are all manageable.(2) The baseline finite element model of Xiaoshawan Huanghe Super Major Bridge is set up. Firstly, the basic theory of optimization algorithm is introduced; secondly, the the initial finite element model is set up according to the design drawings and based on the analytical results the in-situ vibration testing is carried out; In the end, the baseline finite element model is set up based on optimization algorithm and model updating. The baseline finite element model can reflect the dynamic behavior very well and can be used in the future health monitoring.(3) The real-time health monitoring is carried out successfully. The monitoring system records the displacement, stress and temperature of bridge structure under different condition, the setup of monitoring system is helpful for the routine maintenance of bridge. From the available results, the displacement and strain at the survey points are little and vary regularly with the variation of air temperature, the dynamic characteristics varies very little and the variation of bridge deck elevation is also very small. From all the results it can be concluded that the bridge is healthy and in a safe operation condition.(4) Based on the data drawn from the Health Mornitoring System of Xiaoshawan Huanghe Super Major Bridge, the normal limit values were determined. And the safety threshold values were alsl determined based on the baseline FE model. All these values can be worked as the decision indicators for the health monitoring and structural safety assessment of Xiaoshawan Huanghe Super Major Bridge.