Research On Time-dependent Performance And Analytical Method For Long-span Prestressed Concrete Girder Bridge

The project "research on the time-dependent damage accumulation mechanism of large-span prestressed concrete continuous rigid bridge" (No.20060613002) is subsidized by Doctoral Special Fund for Institutions of Higher Learning of the Ministry of Education. Based on this project as well as other research projects, this paper focuses on the universal damages and the associated causes in the case of large-span prestressed concrete continuous rigid bridge. Specifically, several aspects are explored from multiple angles, including the material time-dependent performance, the structure time-dependent performance, construction control etc. Besides, this paper proposes the approaches to structural damage analysis and reinforcement design. It also provides new basis for the treatment of damaged rigid bridge. The main contents of the research are as follows:(1) On the basis of the comprehensive analysis of high performance concrete, time-dependent performance test of early age concrete in the natural environment is conducted, and the HPC time-dependent performance prediction model is proposed;(2) The sources of result error on the time-dependent parameters of prestressed concrete structure are investigated form two aspects:calculation methods and time-dependent parameters. On the basis of the effective modulus of different age, the associated time-step calculation equation is deduced. Also, the simulation model based on different prediction models on shrinkage and creep is established. Finally, the impacts of various factors on the time-dependent performance of bridge structures and the sensitivity of the damage are analyzed;(3) The method of analyzing structural damage based on the time-dependent performance is put forward. The factors that caused the decrease of level of structure performance are analyzed. Also, a more realistic level of bridge performance is identified based on the actual level of performance parameters of the bridge structure. This is a new approach for the damage analysis of PC rigid bridge as well as other types of bridge.(4) On the basis of a large amount of construction control work of large-span concrete bridges completed by the author, the time-dependent performance, overall method of construction control is proposed. This method combines current mature control theories with the theory systems based on structural performance. It discusses various aspects, including determining and tracking control targets, forecast and full control of the level of performance etc.(5) Explored the prevalent problems regarding reinforcement of prestressed continuous rigid bridge, the methods of analyzing damage and time-dependent performance were integrated with the performance-based design method, and the performance-based reinforcement design method is proposed.