Construction Monitoring Of Large-span Prestressed Concrete Continuous Girder Bridge

With the development of bridge engineering construction and the improvement of prestressed technology, more and more large-span prestressed concrete continuous girder bridges were built. To keep the accordance of alignment of built bridges with the design alignment and to insure the safety of bridges in construction, the construction control was paid more and more attention. Based on the construction of the Northern Relief Road Bridge of Longhai Road, this dissertation studied the construction monitoring of prestressed concrete continuous girder bridges.The main research works and results of this dissertation were included below:(1) Based on finite element theory and construction characteristics of the Northern Relief Road Bridge of Longhai Road, construction process simulation was made to get the stress state of the control section.(2) The design parameters sensitivity analysis of the Northern Relief Road Bridge was carried out by means of finite element analysis model, and results indicate that the concrete density, prestressed error and shrinkage and creep have much effect on the deflection and stress of the main girder; pier foundation uneven settlement has great influence on the girder deflection; the elastic modulus of concrete has little influence on the deflection and stress of the main girder.(3) Considering the mechanical characteristics and construction schedule, the scheme of the alignmen and stress monitoring was made to control the entire construction process. Through effective construction monitoring, the development of actual stress state of all stress monitoring sections and the ideal condition meet well during the construction stage. And the alignment state meets the requirement of design.(4) This paper studied the calculation method of measured stress during the stress monitoring. The calculation method considers of concrete shrinkage and creep and Matlab have been applied for calculation. Considering concrete shrinkage and creep, the difference between measured stresses and calculated ones is small. Getting the real stress state of the bridge from measured strain by this method is feasible.(5) Taking Northern Relief Road Bridge of Longhai Road as project background, temperature field of the beam body was measured. Based on temperature field testing, the changing rule of box girder temperature field over time on sunny and cloudy days was analyzed, and then the temperature field distribution form of the girder cross section and the maximum temperature difference distribution function obtained by curve fitting were determined. With the help of finite element software Midas/Civil, the effect of temperature gradient on bridge structure under the maximum cantilever state was analyzed, and the results show that temperature gradient has great influence on the structure deformation.