Research On Tension Control Technology Of Large Span Prestressed Concrete Continuous Beam

So far, the relevant design theory of large area large span pre-stressed concrete frame structure has become increasingly mature, and the problem of construction process has been basically solved, while there is not much intensive research on the construction theory and technology, especially on the analysis and control of structure stress status and deformation during construction period, and strain-pull control of large span pre-stressed frame beam, etc. Based on the station engineering of Baoji south station, this paper makes a deep research on the strain-pull control technology of post-tensioned pre-stressed space frame structure long and large continuous beam. Around the strain-pull difficult control problem of large span pre-stressed frame beam, this paper mainly conclude the following:Firstly, analyses the influence factors of prestress loss of post-tensioned continuous pre-stressed frame beam during strain-pull phase, summarizes the theory analysis method of prestress loss caused by beam side haunch and rigid column lateral restraint that are not covered in current specification. And takes the station B area main structure E-9~E-10 beams as example, calculates the prestress loss in construction process, provide theoretic foundation for later simulation analysis and field monitoring.Then, chooses the continuous 9 spans pre-stressed frame beams at the E axle of the main structure as analysis objects, uses ANSYS finite element software analyzing the influence of different construction sequence to the effective prestress and deformation within the frame beams.Finally, takes the E-9~E-10 beams as control objects, makes theoretical analysis and calculation about the pre-stressed tendons elongation, beam arch value, and the beam body controlling section strain. And ensures the tension effect by field monitering.Through the above theoretical research and field monitoring, the test results show that the pre-stressed construction quality are safe and reliable and can provide a reference for similar projects.