In order to study the fatigue behavior decay law of reinforced concrete structures in cold region under the action of chlorine salt and freeze-thaw, 150-time water freeze-thaw and salt freeze-thaw cycles of reinforced concrete beams were carried out by the quick freezing method, and then the fatigue properties of the test beams were obtained by the four-point bending fatigue test. The fatigue life of the test beam without freeze-thaw is 1,074,282 times, and the fatigue life of the test beam after freeze-thaw is reduced; the minimum fatigue life of fatigue failure is 493,972. The test results show that the residual deflection of the test beam is similar to the relative dynamic elastic modulus, which accords with the damage and failure mechanism of concrete, and the growth rate of residual deflection accords with the law of the block model. The fatigue damage model of reinforced concrete specimens is established, the nonlinear fitting of the damage model is carried out according to the test data, the fitting correlation coefficient is more than 0.98, which indicates that the model can better reflect the damage degree of concrete, and the method of predicting the life of in-service concrete beam is put forward in combination with the concrete damage model.
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