Study On The Durability Evaluation And Maintenance Investsment Decision Technique Of Reinforced Concrete Bridges

Because of the reasons of design, construction and management, under the effects of environment, every kinds of durability disease arise. These diseases take influence to the safety and activity of the structure. Now, most found is invested to the infrastructure construction. The maintenance fund is limited and isn't enough to repair all the bridges. So the problems of durability evaluation and maintenance investment decision are important and needed to be solved urgently. The durability evaluation and remainder life predication can discover the potential danger; provide basis for the repair, reinforcement or removal; avoid the occurrence of heavy accident. Investment decision can help the manager to make the most profitable schedule and allocate the fund properly. Incorporating the scientific and technical development item of construction of Qingdao, this paper performed following studies:1. This paper researches the use of Analytic Hierarchy Process (AHP) in durability evaluation; divides the bridge structure into super structure, bottom structure and other facility by AHP. A two-grade durability evaluation model is established at the base of division.2. This study introduces the theory of gray system into durability evaluation of the bridge, then the weight of the index in the evaluation model is obtained through the method of gray relation analysis, then the durability evaluation grade standard is established. Some research is done in the factors affecting the durability of bridges. The factors are divided into detection index and observation index. The grade standard and white function of detection index, the grade standard of observation indexes are established. The use of grey integrated appraisal in durability evaluation is researched.3. This study generalizes the sort and evaluation criterion of structure life, introduces the durability life criterion in detail. Mechanics and model of carbonization and chloride ion penetration are introduced. Probabilistic model of life prediction of carbonization and resisting chloride ion penetration are established based on carbonization life criterion and chloride ion penetration criterion respectively.4. The total life cycle cost and the benefit of the maintenance item are analyzed. Using the economic indictor obtained by economic analyzing, based on benefit—cost increment, invest decision of the maintenance item can be done. This study provides a quantifiable method to the invest decision.5. By the Visual Basic and Access, the expert system for durability evaluation and maintenance invest decision is developed. An intelligent method of evaluation and invest decision is tried.