Experimental Study on Flexural Fatigue Properties of Reinforced Concrete Beams after Salt Freezing

Abstract

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.

A review of concrete properties under the combined effect of fatigue and corrosion from a material perspective

“…FTCs can accelerate the development of member deflection and speed up the point of crack failure of prestressed concrete beams under fatigue loads [149]. For reinforced concrete beams subjected to FTCs, the residual crack width, relative dynamic modulus, residual stiffness, and residual deflection all exhibit obvious three-stage development with a rapid, then slow and finally accelerated failure [148]. As shown in Fig.…”

“…20, regardless of water FTCs and salt FTCs, the residual deflection development is similar; whereas with the number of FTCs increases, the salt FTCs condition will advance the failure point of specimen fatigue. The presence of chloride salt can reduce the freezing point of the pore solution to reduce the negative effect of FTCs on fatigue damage in the initial stage [148]. However, because the permeability of salt solution to concrete is much greater than that of water, therefore, with the number of FTCs increases, the saturation degree of concrete increases.…”

Durability prediction analysis on mechanical properties of GFRP upon immersion in water at ambient temperature

“…1) is derived based on the nonlinear exponential regression with the help of experimental data (Rao & Husain, 2016). The durability equation for the composite is being established by the ExpDec1 model** (Onephase exponential decay function with time constant parameter) and equation as follows (Yang et al, 2020);…”

Fatigue Performance Prediction of RC Beams Based on Optimized Machine Learning Technology

“…Wang and Li [8] investigated the effect of material randomness on structural fatigue performance by conducting fatigue loading tests on RC beams. Yang et al [9] studied the fatigue performance of RC beams after water freeze-thaw and salt freeze-thaw cycles by conducting four-point bending fatigue loading tests. There are problems such as high intensity, long cycle time, and difficulty in obtaining fast and accurate test results in a short period of conducting a large number of tests.…”