Research On The Mechanical Properties Of The Corroded Reinforcement Bar In Reinforced Concrete Structures

Concrete durability is one of the world-wide concerned problems in the field of the structure engineering. Corrosion of reinforcement steel bar is already recognized as one 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 of the corroded steel bar. Combining with the National Natural Science Foundation of China(No.50478032), following researches were done in this thesis:1,Accelerated corrosion test of reinforced concrete beam through extra impressed current was carried out in the laboratory, and the laws of the nominal strength changes with the corrosion for plain round bar and deformed bar were studied respectively. The study indicates that: for homogeneous steel, the bigger the diameter, the sooner the nominal yield strength reduced; for different type steel bars, the nominal yield strength of the deformed steel decreased more quickly; the change laws of the nominal ultimate strength for homogeneous steel express the same rule with the yield strength, the difference of the nominal ultimate strength reduce between different type steel bars is very little;2,The results of the quick corrosion experiment of the construction members with single reinforcement bar indicate that, the practice mass loss rate of the steel bar was influenced by corrosion rate, the steel type and the diameter of the bar; the real yield strength of the steel does not change with the corrosion, the real ultimate strength of the HRB335 steel bar reduced more sooner than the HPB235; the relationship between the mass loss rate and the weakest area loss rate were established through regression analysis, and the result indicates that the corrosion shape was changed with the bar type and the mass loss rate;3,After the existing research achievements about the mechanical properties reduction of the corroded steel bars were gathered, combining with the test data of the corroded reinforcement concrete beams made in this thesis, the uniform expression of the strength were established, the result of comparation indicates that the change laws of the mechanical properties of the corroded steel bars in quick corroded environment and in marine environment in the structures had much correlation, but there are many differences between them.