Research On Frost Resistance Durability Of Concrete Under Axial Force

Freezing thawing damage has been an important research direction in the research of concrete structure durability damage. At present, the research working on the mechanism of freeze-thaw damage of concrete and the influence factors of frost resistance of concrete has made a lot of results, but there is still much work to do about the analysis of the frost resistance of multi field coupling concrete. Considering the combined action of freezing thawing cycles and stress working condition of concrete, the concrete under axial tension and pressure effect in the freeze-thaw cycle test was designed. Through the pre embedded thread, the tension was applied, and the pressure was exerted by the non bonded prestressed structure. Compared with no stress state of concrete under the same environment, the general rule of the stress state of concrete freeze-thaw damage was gotten. Specific contents are as follows:Two kinds of strength, many kinds of stress level concrete specimens were designed and made. Among them, the C35 stress state is 0.1 times design value of ultimate tensile strength; the C35 stress state is 0.3、0.4、0.5 times design value of ultimate tensile strength and 0.4、0.5、0.6 times design value of ultimate compressive strength。The fast freeze-thaw test of the specimen keeping the stress level had been done. By analyzing its dynamic elastic modulus, mass loss, compressive strength flexural strength and so on, the results show that the stress of the concrete has a great influence on the frost resistance of concrete.According to the test results, the Li Jin-yu frost and thaw life prediction model of the non stress state concrete was modified. By added stress influence coefficient, the modified prediction model can reflect the frost thaw life of concrete under different axial loads, and the accuracy can meet the requirement of actual engineering concrete.The finite element model of concrete freezing and thawing was analyzed based on ABAQUS platform. Calculating the distribution of temperature field of concrete freeze-thaw cycle first, the calculation results imported thermal stress analysis to simulate the process of freezing and thawing cycle. By comparing the calculation results of displacement change and trend of relative loss modulus loss during the test, the model and method are proved to be effective.