Experimental Study On The Compression Fatigue Residual Strength Of Concrete Under Condition Of Sodium Chloride Corrosion

Some components of concrete bridge structures long suffered from high stress cyclic loading, can easily lead to fatigue damage even destruction. In addition to the fatigue problem,the durability problem will be caused when concrete bridge structures long server in corrosive environment. By the compound effect of corrosive environment and cyclic loading, the service life of concrete bridge structure will be greatly reduced. Therefore, it is meaningful to research on the fatigue properties of concrete under the compound effect of corrosive environment and cyclic loading. As the fatigue performance of concrete can be characterized as the attenuation of residual fatigue strength of concrete. To sum up, this paper carried out the experimental study on the compression fatigue residual strength of concrete under condition of Sodium chloride corrosion, and the main research contents are as follows:(1) Selecting NaCl solution whose concentration is 10% to corrode 63 concrete prism specimens, then observing the changes in surface morphology of concrete specimens. static loading test of the concrete specimens was done, the research shown that: the failure mode of specimens corroded by NaCl was different from the failure mode of specimens without erosion, the fatigue life test of specimens corroded by NaCl or specimens without erosion was done to compare their fatigue life change law under the same stress level.(2) Static compression test, the fatigue life test and compressive fatigue residual strength test were done to 126 concrete specimens without erosion or corroded by NaCl. The analysis of the test results shown that: concrete residual strength and fatigue life had large characteristics of dispersion and randomness, it is necessary to introduce the probability statistics method and reliability theory to analyze them.(3) The lognormal distribution and the three parameter Weibull distribution were introduced systematically, the method of parameters regression to the two kinds of probability distribution model using small sample test data was derived, the concrete fatigue life models under different stress level were determined by fitting the distribution parameters, fatigue reliability of an example was calculated by those concrete fatigue lifemodels.(4) Based on the theory of normal distribution, The probability distribution models of the initial and the residual compressive strength of concrete were established using test data of concrete specimens without erosion or corroded by NaCl, by using the probability distribution models of the initial compressive strength and residual strength under different stress level, combination with attenuation model of concrete residual strength, the P-R-N curves of concrete were got, using the P-R-N curves, the concrete residual compressive strength after some fatigue loading times under different stress level can be calculated,and the corresponding reliability can also be given.