The Optimizing Research Of Tensioning Procedure Of Three-Dimensional Prestressed System For Long-Span PC Continuous Rigid-Framed Bridges

Long-span Prestressed Concrete Continuous Rigid-frame Bridges generally use three-dimensional prestressed system, but in the construction process, the application of three-dimensional prestress is a more complex construction technologies. However, the current Chinese Highway Bridge Design and Construction Regulations haven’t stated clearly on the tension procedure of the three-dimensional prestressed system. Even the instructions of the design documents are not the same. Thus the phenomenon of that construction enterprises is random in the process of prestress tension, which will necessarily result in serious security risks.In order to research the influence of internal force of box girder by different tension procedures and put forward a reasonable tension procedure. This paper choose the large-scale finite element analysis software(MIDAS/FEA) to establish the entity finite element model and The Ju River Bridge(continuous rigid-frame bridge) as the research background to do the following researches:(1) Through the accurate model analysis for the timeliness tension of three-dimensional prestressed system, the results indicates that no matter how to adjust the tension procedure, the stress of top flanges and girder webs of box beams is non-uniform distribution along the longitudinal distribution. The calculation results show that at the same time different tension procedure among longitudinal, vertical and horizontal directions has no great effect on the final internal force value of box girder.(2) This paper had compared and analyzed the simulation of the three kinds of transverse and vertical prestressed tension procedures(timeliness tension, integral tension and hysteresis tension) and put forward that from the perspective of the uniform stress distribution along the longitudinal direction of bridges, the lateral and vertical prestressed tension as a whole and hysteresis tension is relatively reasonable tension proc-edure.(3) This paper had simulated and analyzed the reality construction course of The Ju River Bridge(continuous rigid-frame bridge) which had taken into account the effect of temperature gradient, three-dimensional prestressed, Cradle and other load. With the stress capacity, uniform stresses and convenient construction distribution during the construction process taken as restraints, the prestressed single-wire tension procedure-s were taken further research. This paper had put forward a better tension procedure of the three-dimensional stress. The results can provide a reference for the tension procedure of the three-dimensional press of the long-span PC continuous rigid-framed bridges.