Search

• The detection and evaluation of reinforcement elastic stress in RC beams were studied. • The magnetic signal gradient was quantitatively modeled and verified by experiments. • A method based on Bayesian theory was developed to estimate the elastic stress. • This method can be reliably applied for rapid and economic stress detection in RC beams. This study developed a method for detection and quantitative evaluation of the elastic stress of the reinforcement in reinforced concrete (RC) beams. By combining the minimum energy and magnetic dipole theories, a quantitative model of the magnetic signal gradient and magnetization angle was established. The spatial distribution of the magnetic signals and variation of the average gradient with stress in the pure bending section of the RC beams were obtained through four-point bending experiments. The results show that the law of the average gradient with the stress is consistent with that predicted by the theoretical model. Based on the Bayesian theory, a method to evaluate the elastic stress was established, which can be applied for grading the elastic stress of the reinforcement within a certain range of accuracy. [ABSTRACT FROM AUTHOR]

Accurate measurement and assessment of rebar corrosion are critical for the safety and durability of reinforced concrete (RC) structures. The non-destructive self-magnetic flux leakage (SMFL) technology is often employed but still has some difficulties in achieving this goal, especially when the RC structure is under load. Therefore, an SMFL measurement experiment and corresponding finite element simulation of six loaded corroded RC beams were carried out in this study. Then, a dimensionless SMFL quantitative index G i for assessing the corrosion degree of the loaded RC beam was proposed. The experimental and simulated index G i has a similar linear correlation with the corrosion degree of the longitudinal tensile rebars of the RC beams. The corrosion-induced increasing ratio of index G i was up to 500% while that of the load-induced does not exceed 10.6%, which indicates that load has little effect on the SMFL-based corrosion degree assessment of RC beams. Furthermore, a universal grading assessment standard of the corrosion degree of loaded RC beams was established based on the Bayesian model and a G i data set extracted from 500 random simulation combinations of corrosion distribution and load. According to this standard, the corrosion level of the loaded RC beam can be directly determined via the value of G i with an accuracy between 70% and 100%. This work is beneficial for the engineering assessment of the rebar corrosion of loaded RC beams and provides an innovative research idea for this research field. • The SMFL characteristics of RC beams with stress-corrosion coupling were explored. • The proposed SMFL index G i is linearly related to the corrosion degree η of RC beams. • The effect of stress on the linear relationship between G i and η is minimal. • A G i -based corrosion grading standard of loaded RC beam was proposed. [ABSTRACT FROM AUTHOR]

Various structural failure modes exhibit great differences in occurrence probabilities, failure consequences and intrinsic characteristics, etc. Utilising these differences can enhance the effectiveness and efficiency of damage identification research, which has currently received little coverage. Therefore, a new idea, developing mode-specific damage detection methods, is suggested in the paper, with validation on beam structures. Firstly, structural behaviour was investigated from the perspective of stochastic traits and the structure design theory. It was concluded that developing damage detection methods for probabilistically dominant modes had potential to enhance the effectiveness of the identification significantly. Secondly, the strategy was applied to simply supported beams for the purpose of verification. When following the flexural mode, a major failure pattern of the beams, the structures demonstrated a very interesting feature – linearized deflection curves. Hence, damage severity and location indices were defined and an analytical model was built by quantifying the feature and then linking the indices to the curvature of the beams. Thirdly, experiments on reinforced concrete (RC) beams were conducted. The results showed that both the flexural mode and the characteristic of the linearized deflection curves were observed on all specimens; that there was a strong correlation between the damage severity index and the state of the defects on the beams; that the location indices corresponding to damaged and intact sections varied completely differently in quality and quantity. Thus, implementing the mode-specific strategy improves the specificity and efficiency of the damage identification dramatically. [ABSTRACT FROM AUTHOR]