Time-dependent Reliability Analysis Of Reinforced Concrete Beam Under Different Failure Modes

There are a number of bridge structures performance has serious degradation in our country with the development of social economy. The safety of bridge beams is largely below the design specifications and environment requirements. Also, old structures function comparing with new requirements has lagged behind. A large number of existing structures for safety and pure has in the durability of face of the retirement of low threat, urgently need to look at the old bridge structures for repairing and reinforcement. The failure models may be change for the resistance of existing bridge deteriorating with time. So it is important to develop the research of time-dependent reliability analysis of reinforced concrete beam under different failure modes on assuring its service life and determining the best reform strategy.Combining with the national natural science fund project "the research of deterioration model of RC bridge beams and its reliability"(50878031), the mainly research works as follows:(1) This thesis comprehensively described the research status of flexural and shear failure models for existing bridge and the calculation methods of time-dependent reliability.(2) The equivalent resistance method by Gong Jinxin is used to evaluate the time-dependent reliability index due to chloride-induced corrosion of steel area under different failure modes. The results show that the flexural failure is the main failure under the slight corrosion, while the shear failure is dominated under severe corrosion.(3) Autocorrelation coefficient of resistance is calculated on based on assuming resistance belonging to independent increment random process. Considering the influence of autocorrelation coefficient for reliable index, reliable index of the single failure model increases by5%.and the minimum value of each period account for large proportion.(4) The correlation coefficient of flexural and shear failure models is calculated by Ditevsen theory. So the time-dependent reliability of RC beams can be analyzed. Th e time-dependent reliability index changed verylittle whether considering the correlation coefficient of models or not.