Theoretical And Experimental Research On Inclined Section Bearing Capacity Of Reinforced Concrete Box Beams Strengthened With CFS

The box-beam bridge which has greater torsional rigidity and better integrity behavior is quite a common one in Chinese highway bridges. However, a large number of box-beam bridges, only in the use stage, have already generated many oblique cracks on the web, which has quite a negative impact on the structure. Therefore, it is necessary to take effective measures to guarantee the use function of the structure. Carbon fiber sheet (CFS), which has been applied in the reinforcement of the bridge structural engineering, presents several advantages, such as high tensile strength, light weight, excellent corrosion resistance and durability. However, there is a lack of the research on using CFS strengthening the inclined section bearing capacity of box beams at present. Combined with the Natural Science Fund Project of Hunan Province,"Ultimate Load Analysis of PC Continuous Thin-Walled Box Beam Bridge Strengthened with CFS", this thesis takes the method of finite element analysis and experimental study to research the inclined section bearing capacity of the reinforced concrete box beams strengthened with CFS.Based on the nonlinear finite element theory and the parametric design language (APDL) provided by ANSYS, the three-dimensional nonlinear finite element analysis model of the reinforced concrete box beams strengthened with CFS is established, and the analysis of ultimate load is done to study the behavior of the box beams.Considering the split characteristic and force condition of box-beam bridge, four RC box beams are made and the model test of the RC box beams strengthened with CFS is done. The whole damage process of the RC box beams strengthened with CFS is observed, and the mechanical behavior of the oblique section of the box beams is analyzed. The influence of CFS on the ultimate load of the box beams is studied in order to realize the failure mechanism and strengthening effect.Comparing the calculated results with the experimental results, the model is verified to be rationality. Based on the above work, the finite element analysis model of PC continuous thin-walled box-beam bridge strengthened with CFS is established and the calculation of the ultimate load is done to analyze the ultimate load of bridge structures before and after strengthening. Then some helpful conclusions come.According to the theoretical and experimental research and the analysis of engineering background, calculation method of the box-beam bridge strengthened with CFS is put forward. Based on this experimental results and related literature findings, the shearing force formula related CFS in the existing regulations is revised, which provides the reference for engineering design.