Study On The Durability Of Concrete Bridge Under Freeze-Thaw And Deicing Salt Environment In Cold Regions

Due to the particularity of use function and service environment in bridge engineering structure,Often with varying degrees of durability disease before reaching the design life,Resulting the function of structure or structure member and part become invalid earlily with the durability damage accumulation,Causing unnecessary social and economic losses,How do the best treatment after a structural damaged,It needs to optimize the design and scientific and rational assessment of its durability.Current engineering structure design specification mainly use limit state design method based on probability theory,Designing the safety and suitability of the structure on the basis of ensureing that the structure has a certain reliability,Considering the reliability of structural design is different with design reference period,In case of highway bridge,Based on the main variables that affect the reliability of bridge structure,According to the reliability calibration method,Analyzing the reliability variation of the bridge structure,On this basis,Researching the durability evaluation of concrete bridges in cold areas according to the durability rating has a guaranteed rate level.Through analyzing probability distribution and statistical parameters of the main basic variables effecting bridge structural reliability,Calculated the reliability parameter of different stress component of bridge structure under different design reference period by JC method,The results indicate that the target reliability index decreases and the mean of the resistance to achieve the same target reliability index increases linearly with the design reference period approximatively.Considering the difference of design reference period and structure importance factor between bridge Structure and architectural engineering structures,By the conversion relation of reliability parameter,Under the current "durability of concrete structure assessment criteria",Certaining the approximate recommended value of durability grade evaluation for bridge structure,By analyzing durability degradation form and mechanism of material properties of concrete bridge under deicing salt thaw environment in cold areas,Based on the possible main durability damage of concrete bridge in cold area,Assessing the durability grade of existing bridge structure in actual project,Evaluation results show that the research results having stringency to some extent.