Analysis Of Entire Corrosion-crack Process In Reinforced Concrete Column Under Chlorine-loading Environment

The entire process of corrosion-crack in reinforced concrete column protective layeron the condition that the coupling of load and chlorine salt erosion environment has beenreasearched.Focusing on explore the transmission characteristics of chloride in loadedreinforced concrete column and degradation mechanism of protective layer cracking andspalling due to steel corrosion.Based on the loaded creep instrument experiment,the transmission characteristics ofchloride in reinforced concrete on the condition of the coupling of load and chlorine salterosion environment has been reasearched. The load level of specimens are divided intofour groups according to the limit load design value of0%、20%、40%、60%. Thetransmission characteristics of chloride in reinforced concrete in the marine environmentare simulated by dry wet cycling method. A one-year study shows that the existence ofcompression stress expedites the transmission of chloride in the initial loading period andthe transmission speed is faster with the stress level is high. With the loading timeincreasing, the existence of stress hinders the transmission of chloride. The transmission ofchloride efficiency in unstressed reinforced concrete are highest over the same time period.The surface chloride concentration gradually reduce with the compressive stress level raiseover the same time period, the downward trend more obvious with time increases. Chlorineion peak with the increase of stress level changed little. Chloride ion diffusion coefficientof wet and dry cycles increase basically remain unchanged under the same stress level.Thechloride ion diffusion coefficient increased with the increase of stress level increases, butno linear relationship over the same time period.By DIANA, large finite element numerical analysis of the whole process of the rustlayer expansion cracking concrete column load. Used in the process of the simulationanalysis on vertical displacement method to simulate the axial load, adopt the method ofapplying non-uniform rust expansion displacement to simulate the reinforcement corrosionin concrete non-uniform corrosive effect, mainly studied the load level, relative protectivelayer thickness, concrete strength and rebar corrosion morphology and spallingcharacteristics of the process of protection layer burst. Analysis results show that: Theexistence of the vertical load changed the corrosive crack crack development trend, theinfluence of corrosive reinforced concrete cracking at various stages of rebar corrosion rate,stress level is lower, the existence of the vertical load to extend the time of crack of reinforced protection layer outside, but the vertical load applying makes flake reinforcedconcrete protective layer are more likely to happen as a whole; The stages in the samecondition, the protective layer cracking of rebar corrosion rate increased with the increaseof protective layer thickness increases, increases with the increase of concrete strength, butcompared with no load, reduced susceptibility to relative to the thickness of protectivelayer, with the increase of the thickness of protective layer is no longer linearincrease;Under the same load level, non-uniform corrosion protective layer crackingcaused by steel corrosion rate at each stage are less than the uniform corrosion, thusnon-uniform corrosion caused the durability of reinforced concrete members damage moreserious than uniform corrosion; Under the same load level, non-uniform corrosionprotective layer cracking caused by steel corrosion rate at each stage are less than theuniform corrosion, thus non-uniform corrosion caused the durability of reinforced concretemembers damage more serious than uniform corrosion.