Reliability-based Assessment Of Reinforced Concrete Bridges In Commission And Strengthened Condition

Bridges are designed to function over long periods of time. The incidence of structural deterioration increases with bridge age due to corrosion, fatigue and other forms of material property deterioration. During this same period vehicle, loads and legal load limits have been steadily increasing. So exisiting bridges experience changes in both resistance and applied loads which are time variant. Structural elements composed of concrete and reinforcing steel are frequently determined inadequate to sustain current or new load levels imposed on bridges. There is an increasing need, and a great challenge to repair and update the transportation infrastructure of the world. Recently, a new method of retrofit has been studied that uses the addition of externally bonded fiber reinforced polymers (FRPs) to increase load capacity. Therefore, based on the Liaoning Provice Communication Department Key Science Foundation Project (No.0101), this thesis will focus on the following aspects:1. Based on the experimental investigation of 12 reinforced concrete beams, the influence of truck overloads on highway bridge members flexural performance is evaluated. With the value and the times of overload and the percentage of reinforcement as the main parameters, the damnification caused by overloads are studied.2. The performance of 12 beams with external flexure reinforcement was compared to the result of 12 beams with no external reinforcement. The influence of truck overloads on highway bridge members flexural performance is evaluated. With the value and the times of overload and the percentage of reinforcement as the main parameter, the damnification caused by overloads are studied.3. The damnification of diagonal section caused by cycle loading is analysed based on the experiment of 19 reinforced concrete beams. The main varied parameters are reinforcement ratio, shear span and times of cycle loading. With the number of cycle loading increased, the shear capability of reinforced concrete beams are decreased, while the crack width is increased dramatically. The analytical and experimental results can be used for qualitative evaluation of reinforced concrete beam shear capability after damnification.4. Based on the dynamic loading experiment of simply supported beam, the influence of overload on reinforced concrete beams is investigated. The changed parameters are over load value and number. Modal parameters such as frequency, damping ratio are identified from initial state to damaged state. The change law of above modal parameters is obtained. The regress expressions of frequency is given based on the test result. The analytical and experimental results can be used for quantitative dynamic evaluation of reinforced concrete beam after damnification.5. Characteristics of reliability analysis on serviceability limited state for existing reinforced concrete bridges are discussed. The effect of improvement of live load and difference of fuzzy failure bounds on reliability is studied. With crack width as the analysis parameter of normal limited state, The calculation on a reinforced concrete bridge is illustrated herein based on updated inspection information.6. The bridges are structurally deficient particularly for projected increase of trafficloads, which can be called overload. The effect of improvement of live load and difference of fuzzy failure bounds on reliability is studied. With crack width as the analysis parameter of normal limited state, the reliability analysis on serviceability limited state for existing reinforced concrete bridges is analyzed and the result is used to compare with which not considering the influence of overload.7. The statistical parameter of flexural calculate mode on RC beam strengthened with FRP is given after analyzing the lots of experiment results.The influence mechanism of bridge resistance after reinforcement is discussed. According to durability research and corresponding experimentation, the aging of FRP material and interface of FRP and concrete can be ignored. Therefore, the...