Evaluation On Flexural Capacity Of Existing Reinforced Concrete Bridges

Due to natural aging of structural materials, vehicle load increasing, the influence of unfavorable environment and the deficiency of maintenance .some bridges expose various structural deterioration, and it maybe cause the loss of bearing capacity and the decrement in performances of structures resulting in unsafe factors compared with the requirements of the design code. Therefore, the reasonable evaluation on the bearing capacity of existing bridges is not only an urgent issue in order to insuring the safety of the structures, but also an important task needing to be studied further.This paper includes:1. A few common deteriorations in existing reinforced concrete bridges are analyzed, and the characteristics and causes of these deteriorations are generalized. It is a basis for judging harmful defects correctly through appearance check on the beams.2. Main factors in reducing the flexural capacity of reinforced concrete bridge beams and the degrees of influence to the flexural capacity are described in detail. According to the different corrosion rates of reinforcing steels, the change of the mechanical behavior of corroded rebars and bond strength between reinforcement and concrete are analyzed, meanwhile the possible modes of failure of the reinforced concrete beams is given. At the end, based on the factors which influence the flexural capacity, a calculation formula to flexural capacity of the existing reinforced concrete bridges which is based on the corrosion rate combining some practical tested results is established.