The Models Of Deterioration And Durability Evaluation Of Reinforced Concrete Structure

Based on theoretical analysis, finite element simulation and experimental study, the concrete carbonation and concrete cover cracking for steel bar corrosion, deteriorating models of reinforced concrete member and the method of durability evaluation are studied in the paper.This paper presents a stochastic model for predicting the carbonated depth of concrete considering the uncertainties in concrete strength, the location of reinforcement, the environment and the condition of construction. The stochastic model is verified by a number of field data. Based on filed data, a stochastic model for predicting the induced corrosion depth of reinforcement also is presented. The condition of reinforcement initial corrosion has been established. Based on reliability theory, a method for calculating the carbonation durability period and carbonation reliability probability of reinforced concrete also is presented. The target reliability level which determines carbonation-life of concrete structure is also proposed in this paper. A predicting method for carbonation-life is given in this paper. An example of filed test is also given.Based on accelerated electrochemical corrosion experiment and field test, a simplified stochastic model for predicting the corrosion depth of steel bar before concrete cover cracking and a cracking criterion stochastic model for concrete cover are produced in this paper. These models consider the uncertainties in concrete strength, concrete cover depth, diameter of steel bar. Based on the comparison the corrosion depth before concrete cover cracking with that after cover cracking, a simplified stochastic model for predicting the corrosion depth of steel bar after cover cracking is given in this paper. This paper presents an approach for calculating the corrosion cracking durability period and reliability probability of concrete cover cracking. The target reliability level for cover cracking also is given in this paper.The local bond stress-slip relationship between corroded steel bars and concrete is advanced. It is studied that the nonlinear finite element model was simulated to analyze corroded reinforced concrete member. The influence of the corroded degree of steel bar on the stiffness, the slip between the steel bar and the concrete, the coordinate equation of steel strain with concrete strain, theappearance of crack and the failure mechanism are studied with nonlinear finite method. A coordinate equation of steel strain and concrete strain is derived for flexural member. Based on the fact that plane sections before bending don't remain plane after bending, a calculation model for flexural strength of corroded reinforced concrete beam is proposed.The nonlinear finite element is simulated to analyze the eccentrically loaded column. The influence of the corrosive degree of steel bar and eccentricity on the loading performance of eccentrically loaded column is studied. A coordinate equation of steel strain with concrete strain is derived for eccentrically loaded corrosive reinforced concrete column. Based on Ihe fact that plane sections before bending don't remain plane after bending, a calculation model for eccentrically loaded corrosive reinforced concrete column is proposed.Based on accelerated electrochemical corrosion, an experimental investigation on the shear behavior and ultimate shear strength, which included 18 corroded reinforced concrete beams and 3 un-corroded reinforced concrete beams, is presented in this paper. The effect of the corrosive degree of stirrups and the shear span to depth ratio on the shear performance of corroded flexure member is studied. A calculation model for shear strength of corroded flexural reinforced concrete beam is proposed.Since both the resistance and load are time-dependent quantities. They must be considered in the safety evaluation and service-life prediction of deteriorating reinforced concrete structures. The time-dependent reliability analyze are discussed as well.