Lifespan Estimation Of The Existing Reinforce Concrete Bridges

The existing bridges are precious property of the society. And they are the keys to transportation safety. However, there are a large number of bridges which have been deteriorated, damaged and have insufficient load-bearing cap city. It has become a worldwide problem. How to assess these bridges scientifically and reasonably also become a subject that is followed with great interest at home and abroad. Service-lifetime and reliability is estimated considering two models of uniform corrosion with efect of cracks and local corrosion on the theoretic of system simulation and reliability.The conception of nominal virtual height is used to analyze the influence of cracks. The relations between rigidity and service-time are built. And to predict the service life-span of the RC bridges with the FORM. In corrosions of steel, comparison of two models, realistic traffic situation, is studied in the article.The results can be used to predict the service lifetime of RC bridges, and to develop rational and economical maintenance schemes for these bridges.The general thought: some factors which are having worked on the structures are analyzed to show their changes with service time on the theory of simulation of system and reliability. And time-dependent equations are built. With these ,the resisting force can be calculated .With the coefficient of transverse distribution of load,calculated the effect of the dead and active loads on the structure,obtained the reliability of RC members in the different service time. And to predict the bridges' service life-span by the index of object- reliability.