Initial Cracking In Reinforced Concrete Cover And Simulation

The structural damage of reinforced concrete caused by rebar corrosion has led to huge economiclosses and casualties, which aroused extensive concern of the engineering. Currently, many academicscholars have researched in succession, and obtained certain positive results. However, owing to thediscreteness and complexity of different concrete structures, there exist deviations between theoreticaland experiment results. Further researches are still needed on the damage and destruction behavior ofreinforced concrete structure.The concrete around steel is extruded because of rebar corrosion. Concrete cover will crack inradial and longitudinal direction when the tensile stress is larger than the ultimate tensil strength. Itmakes external ions intrude into the surface of steel bar, just aggravating rebar corrosion. When rebarcorrosion achieves a certain degree, cracking expands further even through the concrete cover, justleading to the destruction of component and structure eventually. It reduced the durability and lifetimeseriously. Consequently, studying concrete cover cracking due to rebar corrosion is very critical. Themain jobs in this thesis are as follows:(1) This thesis regarded the concrete cover model as a thick cylinder model to simplify theanalysis of the structural damage caused by rebar corrosion. Mechanics calculation of the model wascalculated by using elastic-plastic mechanics method.(2) By comparing the existing models of corrosion expansion stress and corrosion ratio, andsetting the model parameters, the differences among the existing calculation models are indicated.(3) The reinforcement average corrosion was simulated by the finite element analysis softwareANSYS. The corrosion expansion stress at the time when the concrete cover cracked initially wascalculated with setting model parameters. In this thesis, the rebar numbers and corner rebar werepremeditated, and the factors:“ftk”,“C”,“d” and “S”, which impact the corrosion expansion stresswere analysized. The calculation model of the corrosion expansion stress at the time when concretecover initial cracked were got by the software Matlab regressive fitting.(4) Based on the nonlinear finite element calculation results, the relationship between thecorrosion expansion stress and the corrosion ratio, and the calculation formulas at the time when theconcrete cover initially cracked were obtained.