RELIABILITY ASSESSMENT OF A DETERIORATING RC SLAB BRIDGE STRUCTURE

摘要

Maintenance, repair and strengthening of existing concrete structures either reinforced or prestressed are important activities for the structural engineers. Reinforced concrete (RC) bridges, like other structures in nature, deteriorate with time due to exposure to environmental effects. The main causes of deterioration in bridge structures are the increased and repeated live load and the environmental stressors. This results in reduction of their reliability below an acceptable level. In assessment of existing structure, additional information may be available as a result of collecting and analyzing data for the actual structure. The bridge structures under repeated and increased live loading and environmental stressors experience the reduction in their reliability levels. At any time during the service life of structure, the probabilities of failure of structural members for a given limit state can be evaluated using structural reliability analysis. This paper presents the reliability assessment of structural components of the existing bridge structure under distress due to exposure to aggressive environment using probabilistic methods. The actual strength of concrete in the structure has been found using ultrasonic pulse velocity methods (UPV) before and after repairs of the bridge deck slab. Half-cell potentiometer is used to find the probability of corrosion of steel reinforcement in the slab. Based on the strength of concrete and available reinforcement in the structure before and after repairs, the reliability of the components of the existing bridge structure is estimated in terms of reliability index (P) by First Order and Second Order Reliability Methods (FORM&SORM). Using these values of Reliability Index (P) the extended life of the repaired structure and time interval of repairs can be predicted.