Existing Bridges Evaluation And Service Life Prediction

Because the steel bar rusts away, concrete carbonization, load factor the and so on change influence , the bridge structure performance degenerates gradually along with the time, causing bridge service life reducing. Therefore existing bridges evaluation and service life prediction has aroused the engineers and technicians' widespread interest.Existing bridges evaluation and service life prediction is a question which our bridge engineering urgently awaits to be solved. In this paper, a method of existing bridges evaluation and service life prediction based on time-dependent reliability analysis is presented. According to the structure weaken rule, we can forecast the service life of existing bridges structure .And proposed in this foundation , three kinds of bridge structure reinforcement plans based on time-dependent reliability analysis is presented , and the efficient appraisal to these three kind of plans have carried on. The main achievements are briefly mentioned as follows:1.Induce and summarize the domestic and foreign method of bridges structure appraising, and specifically introduce bridge appraisal method based on reliability theory.2. In detail introduce the concept of structure safety reliability and practical computation method of reliability index — β(t)3. The changes rule of the factors which influences structure resisting force have established, including concrete intensity changing rule, steel bar intensity changing the rule, the influence rule of computation pattern not determinism to the resisting force. the changes rule of structure resisting force and structure load statistical rule and its changing rules have established. The limiting condition equation has established and elaborated the computation method of existing bridges' time-dependent reliability index — β(t)4. According to weaken rule of the bridge structure performance, forecast of the bridge structure residual life has carried on.5.Three kinds of methods of bridge structure reinforcement based on time-dependent reliability theory are presented. There are: "abolishing the old bridge,reconstructs the new bridge " >" repairs only when badly damaged " ," repairs when it has damage ", and the economical analysis to these three methods has carried on to provide the powerful basis for the engineers and technicians decision-making to the bridge reinforcement.