• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.247-259
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• 2017

This paper presents a fatigue assessment model that was developed for corroded reinforced concrete (RC) beams strengthened using prestressed carbon fiber-reinforced polymer (CFRP) sheets. The proposed model considers the fatigue properties of the constituent materials as well as the section equilibrium. The model provides a rational approach that can be used to explicitly assess the failure mode, fatigue life, fatigue strength, stiffness, and post-fatigue ultimate capacity of corroded beams strengthened with prestressed CFRP. A parametric analysis demonstrated that the controlling factor for the fatigue behavior of the beams is the fatigue behavior of the corroded steel bars. Strengthening with one layer of non-prestressed CFRP sheets restored the fatigue behavior of beams with rebar at a low corrosion degree to the level of the uncorroded beams, while strengthening with 20- and 30%-prestressed CFRP sheets restored the fatigue behavior of the beams with medium and high corrosion degrees, respectively, to the values of the uncorroded beams. Under cyclic fatigue loading, the factors for the strengthening design of corroded RC beams fall in the order of stiffness, fatigue life, fatigue strength, and ultimate capacity.

• Computers and Concrete
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• v.22 no.2
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• pp.167-182
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• 2018

The modeling of loss of bond between reinforcing bars (rebars) and concrete due to corrosion is useful in studying the behavior and prediction of residual load bearing capacity of corroded reinforced concrete (RC) members. In the present work, first the possibility of using different methods to simulate the rebars-concrete bonding, which is used in three-dimensional (3D) finite element (FE) modeling of corroded RC beams, was explored. The cohesive surface interaction method was found to be most suitable for simulating the bond between rebars and concrete. Secondly, using the cohesive surface interaction approach, the 3D FE modeling of the behavior of non-corroded and corroded RC beams was carried out in an ABAQUS environment. Experimental data, reported in literature, were used to validate the models. Then using the developed models, a parametric study was conducted to examine the effects of some parameters, such as degree and location of the corrosion, on the behavior and residual capacity of the corroded beams. The results obtained from the parametric analysis using the developed model showed that corrosion in top compression rebars has very small effect on the flexural behaviors of beams with small flexural reinforcement ratio that is less than the maximum ratio specified in ACI-318-14 (singly RC beam). In addition, the reduction of steel yield strength in tension reinforcement due to corrosion is the main source of reducing the load bearing capacity of corroded RC beams. The most critical corrosion-induced damage is the complete loss of bond between rebars and the concrete as it causes sudden failure and the beam acts as un-reinforced beam.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.843-854
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• 2013

This paper presents experimental research work for the evaluation of ultimate flexural behaviors of prestressed concrete beams with a corroded tendon. In order to evaluate the effects of loss of prestress or loss of tendon area on the ultimate flexural strength of prestressed concrete beams, static load tests are conducted using five prestressed concrete beams. After exposing prestressing tendons in two test beams using 25mm drill bit, the exposed tendons were corroded using an accelerating corrosion equipment to simulate loss of tendon area. During the tests, steel strains, concrete strains and displacements at the center of test beams were measured, and acoustic emission measurements were conducted to detect wire fractures. Based on the test results, evaluation method for predicting flexural strength of prestressed concrete beams with corroded tendons is investigated. In addition, evaluation methods for predicting the existence of corroded tendons in post-tensioned prestressed concrete beams at service loads are discussed.

• Computers and Concrete
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• v.31 no.1
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• pp.33-52
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• 2023

This paper proposes and validates the extension of two models, previously formulated for the evaluation of the shear strength of reinforced concrete members with un-corroded reinforcements, to the case of beams with corroded stirrups. These extended models are based on the plasticity theory (this model has been proposed in the past by one of the authors) and on the simplified modified compression field theory. The response of these models is compared with that of the compression chord capacity model, which has recently been embedded with modifications that simulate the effects of steel corrosion. These latter modifications are first discussed and then introduced into the other two models. An existing database of slender and non-slender beams tested in laboratory by other researchers is revised and improved. Finally, all the considered models are applied to the selected specimens and a comparison is drawn between the shear strength resulting from the considered models and the shear strength resulting from the laboratory tests. The effects of corrosion on some important parameters of the ultimate shear response of the reinforced concrete beams are also discussed.

• Structural Engineering and Mechanics
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• v.27 no.3
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• pp.347-363
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• 2007

Assessment of structural behaviour of corrosion affected structures is an important issue, which would help in making certain decisions pertaining to the inspection, repair, strengthening, replacement and demolition of such structures. The paper presents formulations to predict the loss of weight and the loss of cross-sectional area of the reinforcing bar undergoing corrosion based on the earlier study carried out by the present authors (Bhargava et al. 2006). These formulations have further been used to analytically evaluate the ultimate bending moment and ultimate shear force capacity of the corroded concrete beams. Results of the present study indicate that, a considerably good agreement has been observed between the experimental and the analytically predicted values for the weight loss and reduction in radius of the corroded reinforcing bars. A considerably good agreement has also been observed between the experimental and the analytically predicted values of ultimate bending moment and ultimate shear force capacity for the corroded concrete beams.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.129-135
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• 1999

Reinforced concrete structures are constructed under the basic assumption of perfect bonding between steel and concrete. The corrosion of steel in the reinforced concrete beams results in the excessive cracks and gradual deterioration of concrete. This paper are concerned about the slip characteristics of reinforced concrete between steel and concrete. The accelerated test by external power supply was conducted with the three corrosion rates in the laboratory. As a result, it was obtained as follows: (1) the yield strength of steel was reduced according to corrosion states. (2) the equivalent steel area should be considered for detailed analysis. (3) According to the use of corroded steel or not, slip amounts between concrete and steel in test beams increased as the corrosion rate increased. These results can be explained from the bond loss between concrete and steel in test beams.

• Steel and Composite Structures
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• v.10 no.6
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• pp.475-487
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• 2010

Most of steel structures in various industries are subjected to corrosion due to environmental exposure. Corrosion damage is a serious problem for these structures which may reduce their carrying capacity. These aging structures require maintenance and in many cases, replacement. The goal of this research is to consider the effects of corrosion by developing a model that estimates corrosion loss as a function of exposure time. The model is formulated based on average measured thickness data collected from three severely corroded I-beams (nearly 30 years old). Since corrosion is a time-dependent parameter. Analyses were performed to calculate the lateral buckling capacity of steel beam in terms of exposure time. Minimum curves have been developed for assessment of the remaining lateral buckling capacity of ordinary I-beams based on the loss of thicknesses in terms of exposure time. These minimum curves can be used by practicing engineers for better estimates on the service life of corrosion damaged steel beams.

• Structural Engineering and Mechanics
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• v.47 no.6
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• pp.773-790
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• 2013

Bending behaviors of corroded reinforced concrete (RC) beams under repeated loading were investigated experimentally. A total of twenty test specimens, including four non-corrosion and sixteen corrosion reinforced concrete beams, were prepared and tested. A numerical model for flexural and cracking behaviors of the beam under repeated loading was also developed. Effects of steel corrosion on reinforced concrete beams regarding cracking, mid-span deflection, stiffness and bearing capacity of corroded beams were studied. The impact of corrosion on bond strength as the key factor was investigated to develop the computational model of flexural capacity. It was shown from the experimental results that the bond strength between reinforcement and concrete had increased for specimen of low corrosion levels, while this effect was changed when the corrosion level was higher. It was indicated that the bearing capacity of corrosion beam increased even at a corrosion level of about 5%.

• Steel and Composite Structures
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• v.34 no.1
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• pp.155-170
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• 2020

Different parameters potentially affect the properties of corroded reinforced concrete beams. However, the high number of these parameters and their dependence cause that the effectiveness of the parameters could not be simply identified. In this study, an adaptive neuro-fuzzy inference system (ANFIS) was employed to determine the most influencing parameters on the properties of the corrosion-damaged reinforced concrete beams. 207 ANFIS models were developed to analyze the collected data from 107 reinforced concrete (RC) beams. The impact of 23 input parameters on nine output factors was investigated. The results of the paper showed the order of influence of each input parameter on the outputs and revealed that the input parameters regarding the uncorroded properties of concrete beams are the most influencing factors on the corresponding corroded properties of the beams.

• Structural Engineering and Mechanics
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• v.20 no.3
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• pp.265-277
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• 2005

This paper is focused on fractal analysis of the surface cracking, a new tool for safety evaluation of corroded reinforced concrete (RC) beams. Comprehensive experimental investigations, including flexural tests, coupon tests on strength evaluation of corroded concrete and rusty rebar, and pullout tests to determine bond strength between concrete and rebar were carried out on nine Corroded Reinforced Concrete Beams (CRCB) exposed to an aggressive environment for more than 10 years. In combination with test results from a previous study on CRCBs fabricated in the laboratory from accelerated methods, it is found that, for both types of beams, the surface cracking distributions are fractal in character at loading and failure stages. Fractal dimension is calculated for all specimens at different corrosion states based on fractal analysis method. Relationships between the fractal dimension and mechanical properties of corroded concrete, rebar corrosion ratio, and ductility of CRCBs are discussed in detail. It is concluded that the fractal dimension can act as a damage index and can be efficiently used to describe the corrosion state of CRCBs.