To investigate the combined effect of load and steel corrosion on the flexural performance of recycled aggregate concrete beams, considering three types of aggregate replacement ratios (i.e., 0%, 50%, and 100%) and four levels of load (i.e., 0, 0.2, 0.4, and 0.6), 12 beams were designed for accelerated corrosion test and four-points bending test. The load was applied to beams by using a designed loading device before the accelerated corrosion test. After the accelerated corrosion test, four-point bending test was conducted to measure the flexural performance of beams. The results showed that, with the increase of load level applied to beams before accelerated corrosion test, the number of bending cracks on the bottom of corroded beams after four-points bending test decreased, while the average spacing of bending cracks increased. The effect of aggregate replacement ratio on the average spacing of bending cracks was more significant than that of steel corrosion. Yield moment capacity and ultimate moment capacity of corroded beams had a strong linear relationship with the maximum mass loss of

Reinforced concrete (RC) structures suffer from different types of loads during service life, and the corrosion characteristics of steel bars embedded in concrete under load are different from those under non-load. In this paper, when the interface between steel bars and concrete (IBSC) cracked and the concrete cover surface (CCS) cracked, the effects of load on the critical corrosion depth of steel bars were analysed based on the thick-walled cylinder model, and a prediction model for the corrosion-induced longitudinal cracking (CLC) time (i.e., initiation cracking time) of the CCS of RC structures under load was proposed. Finally, the influence of load on the CLC time of CCS was discussed on the basis of the proposed prediction model. The results showed that the load had a significant effect on the critical corrosion depth of steel bars when the IBSC cracked induced by corrosion, while the influence of load on the critical corrosion depth of steel bars when the CCS cracked induced by corrosion was not obvious. When the CCS cracks induced by corrosion under load, the influence of the rust-filling layer on the critical corrosion depth of steel bars was larger than that of the load. With the increase in load, the CLC time of CCS decreased. The calculated values of the proposed prediction model were in reasonable agreement with the experimental values, which can provide a reference for durability evaluation and service life prediction of RC structures and lay the foundation for the investigation of the corrosion depth of steel bars in concrete under load.

In order to realize the probability prediction of concrete carbonation depth, this paper proposed a probabilistic prediction model of carbonation depth based on 433 sets of existing experimental data. First, considering the influence of water‐binder ratio, fly ash content, stress level, and carbonation time, a deterministic prediction model of carbonation depth was established based on stepwise regression method. Then, based on the established deterministic prediction model, considering the influence of aleatory and epistemic uncertainties, a probabilistic prediction model of carbonation depth was established, and the posterior distributions of the parameters in the probabilistic prediction model were updated iteratively by using Bayesian theory and Markov chain Monte Carlo method, and the influence of standard deviation of prior distribution of the parameters in probabilistic prediction model on their posterior distributions was discussed. Finally, the prediction accuracy of the probabilistic prediction model was verified by comparing with another 127 sets of existing experimental data and the predicted values of the deterministic prediction model, and the effect of the standard deviations of prior distribution of the parameters on the prediction accuracy of the probabilistic prediction model was analyzed. The results showed that the prediction accuracy of the proposed probabilistic prediction model of carbonation depth after three updates was higher than that of the deterministic prediction model. When the standard deviation of prior distributions of the parameters in probabilistic prediction model was 100, the proposed probabilistic prediction model after three updates had the highest prediction accuracy. Under the tensile stress state of concrete, the prediction accuracy of the probabilistic prediction model was improved by 26.76% compared with the deterministic prediction model, and when the concrete under compressive stress state, the prediction accuracy of the probabilistic prediction model was 44.07% higher than that of the deterministic prediction model.

Since reinforced concrete members suffer from different types of loads during their service life, the steel bars embedded in reinforced concrete members can be easily corroded in chloride‐laden environment. To investigate the influence of combined effect of load and steel corrosion on the flexural stiffness of recycled aggregate concrete (RAC) beams, 12 RAC beams were prepared and tested. The effects of load level (i.e., the ratio of the load applied to beams to the ultimate load) and recycled coarse aggregate (RCA) replacement ratio (i.e., the ratio of RCAs to replace natural coarse aggregates) on the internal force arm coefficient of cracking cross‐section, the elastoplastic resistance moment coefficient of cross‐section, and the strain incongruity coefficient of corroded tensile steel bars were analyzed, and a calculation model for flexural stiffness of RAC beams under combined effect of load and steel corrosion was established. The results showed that when the ratio of bending moment to ultimate bending moment of the pure bending part of beams was within 0.55–0.80 and the average mass loss of tensile steel bars was less than 3.23%, 0.85 could be adopted as the internal force arm coefficient of cracking cross‐section. The elastoplastic resistance moment coefficient of cross‐section was approximately a constant when the corroded RAC beams were in the service stage, while it increased obviously with the load level. There was a strong linear relationship between strain incongruity coefficient and average mass loss of tensile steel bars during the service stage of corroded RAC beams, and the strain incongruity coefficient increased linearly with the load level. The calculated values of the model of flexural stiffness proposed in this paper were in reasonable agreement with the experimental values.