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The steel ring restrainer (SRR) is a novel device for bridges, the use of which has emerged in recent years to prevent the occurrence of unseating damage. However, since the restrainer is usually installed in regions with harsh atmospheric corrosive environment, it is easily corroded. To investigate the mechanical performance of SRRs with corrosion damage, corrosion patterns of SRRs under atmospheric corrosive environment were analysed, four corroded SRR specimens were fabricated and subjected to monotonic load testing. Based on the experimental results, the validity of an associated finite element (FE) model was verified. Then, 756 FE models of SRRs with general, and local corrosion damage were established to supplement the test results. The experimental and analytical results show that the general corrosion can decrease the ultimate strength, initial stiffness, and secondary stiffness of SRRs, and the local corrosion can also affect the ultimate strength of SRRs. On the other hand, general corrosion has little influence on the variation tendency of force-displacement curve and failure modes of SRRs, while the failure modes of SRRs with local corrosion are significantly affected by the local corrosion rate and regions of local corrosion. Finally, based on the results of experimental and numerical simulation, formulae for estimating the ultimate strength and ultimate displacement of SRRs with corrosion damage were derived. [ABSTRACT FROM AUTHOR]

This article presents an investigation on corrosion damage effects on the shear bearing capacity of reinforced concrete (RC) beams after a fire. Accelerated corrosion tests were conducted using four RC beams designed with corrosion crack widths ranging from 0.1 mm to 0.3 mm to simulate an aggressive corrosion-prone environment. One control beam (B1) did not undergo accelerated corrosion. The fire test was conducted separately on each beam for two hours to explore how the different widths of corrosive cracks affect heat propagation at elevated fire-induced temperatures. A residual capacity test determined the effects of corrosion on the beams' residual shear strength after a fire. The experimental results showed that corrosion cracks accelerate the heat propagation in concrete during a fire; moreover, the post-fire residual shear strength for corroded RC beams slightly decreased with an increasing degree of corrosion on the stirrups. The authors also developed a corresponding simplified calculating method to determine residual shear strength, which showed shear design provisions that could improve some existing codes. [ABSTRACT FROM AUTHOR]

To investigate the flexural behavior of corroded steel beams strengthened by carbon fiber reinforced polymer (CFRP) plate, flexural test of five steel beams were carried out. The effects of corrosion and prestressing force levels on the flexural capacity, failure modes and interfacial stress were investigated. Meanwhile, considering the corrosion surface the calculation method of flexural capacity of corroded beams strengthened by CFRP plate was also established. The results showed that failure modes of corroded beams were the fracture of the CFRP plate after the shear failure of interface on the mid-span and fracture location of CFRP plate was mostly at the loading point. The rough surface of the corroded steel can enhance the efficiency of stress transfer at the interface, thereby improving the effective bond length of the interface. The shear stress was mainly concentrated on the CFRP plate end, and peak value appeared at the loading point. Compared the reference beam, the ultimate flexural capacity of the corroded beam strengthened by CFRP plate with 15% prestress level increased at a ratio of 21%, and utilization ratio of the CFRP plates was up to 71.59%. [ABSTRACT FROM AUTHOR]

The corrosion of prestressed rock bolts (PRBs) has become a serious problem threatening the durability of prestressed anchorage structures during their service. This paper aims to investigate the corrosion damage mechanisms of the free lengths of PRBs subjected to an aggressive environment. During the experiment period, the corrosion behavior of the rock bolts was analyzed considering the influence of prestress under different pH (4, 5, 6, 7, and 8) amounts and several oxygen flow rates (OFR, 0 cm3/min, 40 cm3/min, 80 cm3/min, 120 cm3/min, and 160 cm3/min). Based on the electrochemical analysis, a corrosion rate (CR) development model of the PRBs related to the OFR was developed. The results indicated that the prestress had a great influence on the corrosion of the rock bolts. In the process of corrosion, the PRBs were in an activated state, and no passivation region was formed all the time. The corrosion degree of PRBs increased remarkably with an OFR ranging from 0 cm3/min to 80 cm3/min, and then it reached a threshold value. Additionally, the CR increment was insensitive to the OFR when the pH value was constant. It was observed that the loss rate of the ultimate elongation was larger than the other mechanical properties such as the ultimate tensile load loss rate and the elastic modulus. The effective stress loss of the PRBs under different conditions indicated that more attention is needed to be given to the specimens immersed in solutions with an OFR greater 40 cm3/min and pH lower than 6. [ABSTRACT FROM AUTHOR]