Research On Anti-bending Capacity And Ductility Of Corroded Reinforced Concrete Beam

Concrete durability is one of the world-wide concerned problems in the field ofthe structure engineering. Corrosion of reinforcement steel bar is already recognized asone of the most important factors effect the durability of reinforced concrete structures,it is particularly important to research the change laws of the mechanical properties ofthe corroded steel bar. Combining with the National Natural Science Foundation ofChina(No.50478032), following researches were done in this thesis:1) The variation regularity of the ultimate anti-bending capacity of therectangular-sectioned beam with different corrosion has been obtained through thequalitative analysis of 48 beams (32 corroded beams and 12 comparing beams) withaccelerated corrosion;2) The conclusion has been obtained that the strain of corroded steel bar andconcrete no longer fit in with the assumption of plane section through the analysis ofthe strain data, the strain relation of steel bar and concrete in the mid-span section ofvariously corroded beams at ultimate has been obtained. Through the building of newgeometric relation, the expression of the height of compressive area in the corrodedbeam with rectangular section has been deduced, and the formula with corrosion rateas the main variable for the anti-bending capacity of the corroded concrete beam hasbeen suggested and verified by experiment.;3) The influence of steel bar corrosion and the concrete regression to the flexureductility coefficient of the corroded structure component has been analyzed. Based onthe relation of steel bar and concrete at yield and ultimate, the expression for theflexure at yield and ultimate of corroded reinforced concrete beam, and the model forthe calculation of the flexure ductility has been built. The variation character of flexureductility of different corrosion beam has been analyzed through the M-φcurve.