Research On Birdge Durability Evaluation Under Environment Of De-icing Salt And Freeze-Thaw Cycle

For the durability evaluation of bridge, when weight is determined in the courseof establishing durability evaluation model, it has been fluented by too muchsubjection or confusion of subjective weight and objective weight. Most of theprevious evaluation models are only applicable to the general atmosphere, but theenvironment of de-icing salt and freeze-thaw cycle in cold regions in north China isnot targeted. Therefore, a bridge durability evaluation model is built specially for theenvironment of de-icing salt and freeze-thaw cycle in this paper.Factors of bridge durability disease are summarized, and influence mechanism isanalyzed. Non-linear relationship within and among bridge durability factors,durability disease and durability evaluation indexes. Refer to evaluation indexesrequired in Standards for Technical Condition Evaluation of Highway Bridges（JTGTH21-2011）. Relative dynamic modulus of elasticity, mass loss rate, chloride iondiffusion, chloride ion concentration and erosion of chloride ion critical concentrationthese indexes are introduced in evaluation system for environment of de-icing salt andfreeze-thaw cycle, and then the whole evaluation system for environment of de-icingsalt and freeze-thaw cycle will be established.Classification criterion of each durability index is determined, and single indexmeasurement functions are built using uncertainty math theory. Based on Standardsfor Technical Condition Evaluation of Highway Bridges and uncertainty math theory,a hierarchy structure model is established. The concept and calculation method ofweight of classification and weight of importance in this model are elaborated.Some bridge in Liaoning Province is selected as the project example to verify thefeasibility and applicability of the model. The three uperstructure components of somebridge located in Changchun City is selected as the project example to evaluate theirdurability using the model built in this paper and Standards for Technical ConditionEvaluation of Highway Bridges, and the two results are compared to verify theaccuracy and sensitivity of this paper.The three uperstructure components of some bridge located in Changchun City isselected as the project example to sort their durability using the model built in thispaper, as to preferentially maintain the bridges of which durability are much worsewhen time, manpower and material resources is limited, which can provide basis forscientific management and maintenance of bridges.Based on Matlab R2010a, a software which named Bridge Durability EvaluationSystem under Environment of De-icing Salt and Freeze-Thaw Cycle is programmed.It is used to evaluate durability of exsiting bridges to verify its accuracy. With theapplication of this software, the math foundation is not so required for engineers,which is convenient for application and promotion of the model built in this paper.