The Deterioration Model And Prediction Of RC Beam Bridges

Bridges will deteriorate and damage because of the natural environment and the long-term usage. These degenerations will affect the safety and suitability of the structures. For this reason, knowing the conditions well and predicting the trend of deterioration of bridges become important increasingly for bridge maintenance. Based on above point, the thesis analyzes methods of deterioration prediction and carrying capacity assessment for reinforced concrete beam bridges on the basis of current research and mechanism of deterioration of reinforced concrete structure.Above all, two primary factors, material and external conditions, which result in bridge deterioration are analyzed. Then methods of deterioration prediction used in bridge management are summarized. Markov model and CBR model are illustrated with examples. As a result of carbonization of Concrete, Corrosion of reinforcement is the major factor of structure deterioration in common atmosphere environment. As viewed from engineering application, through analyzing the current models of carbonization of concrete and corrosion of reinforcement, models which use W/C ratio and cement content as main factors should be adopted and corrosion speed affected by crack of concrete cover should be taken into account, applied method is achieved by comparison. As an example, the primary factors which affect carrying capacity of corroded concrete bridges are considered to include reduction of reinforcement section and yield strength and bonding stress between corroded steel bars and concrete. According to these factors, a method to calculate the bending strength of corroded reinforced concrete beam is founded. Then the service life of corroded beam is predicted with the standard of bending strength. The result of sensitivity analysis for yield strength reduction factor and coordination coefficient indicates that the influence on useful life of reinforced concrete beam bridges by selecting different parameters is greater than carrying capacity. At last, a method to improve durability of reinforced concrete beam bridges is presented.