Experimental Research On Flexural Performance Of The Vertically Tensioned Prestressed Concrete Beams

The vertically tensioned prestressed concrete(VTPC) is a new type of prestress technique that was initiated by Chongqing Jiaotong University. By now, it has been successfully applied to seven bridges such as Hongcaofang Bridge and Xujiagou Bridge on Yuqian expressway. In order to further improve the design theory of VTPC bridge and compile the relative clauses in the Code for Design of Vertically Tensioned Prestressed Concrete Bridges. Based on the tested results from ten pieces of VTPC bending beams, the thesis emphatically studies and analyses some aspects of the flexural Performance at the beam's tensioning and serving stages.The main contents discussed in this thesis are generalized as follows:1. Analysing the mechanical performance and the control method at the tensioning stage through testing and studying the relationship between the tention force and the camber during the course of vertically tensioning;2. Bettering the design of the vertically tentioning equipment and fittings, and analysing the rational orientation and configuration of the prestressing steel bars;3. Discussing the computation of prestress losses of VTPC beams and the loss combination at each working stages;4. Describing and analysing the mechanical performance of VTPC beams during statical and repeated loading tests, the mechanical behavior before and after cracking point, and the cracks'development and the cross-section failure forms;5. Analysing the main factors influencing the beam rigidity and structure deformation, and proposing corresponding formula of calculation, the suggested formula agree -ing well with the tested results;6. Validating the computation of the cracking bending moments, analysing the main factors which influence the secondary cracking bending moments and cracks' width, and proposing corresponding formula, the suggested formula agreeing well also with the tested results.