Study On Ultra Thin Beam Of Double Pre-stressed Composite Structure And Its Experiment

To deal with the great reversed deflection in the procedures of tension or creep of ultra thin beam bridge, a new structure, that is the double pre-stressed composite structure, is put forward in this thesis. A lot of studies are made on its performance and characteristic in construction, creep and use phase, from both theoretical analysis and experimental study.The idea about the double pre-stressed composite structure is coming from the development of ultra thin beam, combining with the problems in engineering practices and other existing pre-stressed structures' characteristics. In this thesis, the primary principles and construction technology of double pre-stressed composite structure are based on the introduction of operation of experiment.Then, focusing on the construction technology of double pre-stressed composite structure, the structure analysis methods in this phase is introduced. Compared with normal pre-stressed structures in experiments, this new structure characteristics and virtues are listed to support its application values and popularize prospect. Further more, some factors, which may affect those characteristics, are full investigated.Based on the linear creep theory and deformation coordination principle, the calculation method and computing formulas about the redistribution of stress are brought forward, and its effect factors are investigated in this thesis. Compared with the normal pre-stressed structures, it is proved that its effect factors can effectively decrease the reverse deflection and its application values.The numerical method, which uses the program and experimental validation are employed to research the differences, which is summing up later, between the double pre-stressed composite structure and the normal ones. After that, the calculation method about double pre-stressed composite structure's bearing capability and deflection are investigated, which provide the consults to future research and design works.Finally, on the basis of summarizing full thesis, several questions still required more studies are put forwards.