Study On Existing Reinforced Concrete Structure Deterioration Evaluation And Prediction And Maintenance Decision

The performance of existing structures deteriorates under the effect of the surrounding environment as its service life increases, and some of the existing structures can not meet the requirements for use, as a result, they need to be maintained or reinforced. China is at the period when new constructions and maintenance & reconstruction are paid to equal attention, and the stage that maintenance & reconstruction take up most investment in constructions is approaching. According to the experience of the developed countries, the cost on the structures detecting, maintenance, and reinforcement can be very high. So it is important to evaluate the maintenance scheme carefully before it is carried out.To gain the best benefit at minimum cost in prerequisite of meeting the structural reliability, the dissertation introduced the LCC theory to the existing structures maintenance management. Taking a RC structure for example, the dissertation studied the deterioration situation evaluating and prediction of existing structruces, and introduced the methods of maintenance scheme economic evaluation.Through the analysis of the life cycle cost theory, structural reliability theory, the methods of assessment, and deteriorate mechanism, it indicates that the factors influencing assessment and prediction of structure is various and uncertain. As a result, some factors such as determination of reliability index, determination of judgment matrix and determination of existing structure deterioration model will affect directly the quality of the assessment of existing structure, the prediction of residual life and the analysis of the life cycle cost.Based on the analysis mentioned above, the fuzzy-AHP assessment model is established based on extension theory and a fold line model for structure deterioration is put forward, furthermore, the model of life prediction of existing structure is built. A set of systematic assessment method, namely, fuzzy-AHP assessment-- Monte Carlo Simulation—LCC evaluation, is implemented on an actual reinforced concrete frame structure and the results show that the proposed model and method is reliable.