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- ArticleYalnız künye2018Confinement Effect of Geo-grid and Conventional Shear Reinforcement Bars Subjected to Corrosion
Yalciner, Hakan; Kumbasaroglu, Atila; Ertuc, İbrahim; Turan, Ahmet İhsan
An experimental study was performed to examine the effects of polyester geo-grid as a shear reinforcement bar for corroded and uncorroded reinforced concrete beams. The main aim of this study was to investigate the effect of geo-grids on flexural strength, moment-curvature, bond–slip and crack patterns for uncorroded and corroded reinforced concrete beams. For each parameter, a geo-grid confinement technique was compared with conventional reinforced concrete beams as a function of corrosion level. The experimental program consisted of testing ten reinforced concrete beams for two different configurations of shear reinforcement bars at six different corrosion levels (0% and approximately 2, 3, 5, 6, and 9%). Test specimens were subjected to an accelerated corrosion method to corrode the reinforcement bars using a full-scale corrosion pool. Actual corrosion levels were obtained from fully extracted reinforcement bars by breaking the concrete. At the same overall corrosion levels which were differed at longitudinal and transverse reinforcement bars at the same applied corrosion current time for different RC beams. Obtained actual corrosion levels with the aid of fully extracted reinforcement bars from concrete provided to examine the effect of corrosion levels by considering the type of reinforcement bars. The results indicated that the performance of the polyester geo-grid was very poor compared to conventional steel stirrups, even at this stage of corrosion. It was found that the utility of a geo-grid as shear reinforcement bars in reinforced concrete beams is not proper.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2018Effect of corrosion on flexural strength of reinforced concrete beams with polypropylene fibers
Bicer, Kamil; Yalciner, Hakan; Pekrioglu Balkıs, Ayse; Kumbasaroglu, Atila
An experimental study was performed to investigate the effects of polypropylene fibers on uncorroded and corroded reinforced concrete beams. Three different volume fractions of polypropylene fibers having 0, 0.5, and 1.5%, were tested at four corrosion levels of 0% and approximately 5, 7, and 9%. A full scale of an accelerated corrosion pool was used for the accelerated corrosion process. Reinforced concrete beams were used for an under monotonic bending test. The contribution of the actual corrosion levels of transverse and longitudinal reinforcement bars to the total corrosion levels were obtained from reinforcement bars fully extracted from concrete. Flexural strength, bond-slip, and moment-curvature relationships were examined for uncorroded and corroded reinforced concrete beams. A new model was developed to predict the flexural strength of corroded reinforced concrete beams. The proposed model for predicting the residual flexural strength of corroded beams was compared with test data published in previous studies. Furthermore, a novel model is presented for improved predictions between the actual and theoretically estimated corrosion mass losses, based on Faraday's law, with the aid of fully extracted reinforcement bars. The model used to predict the flexural strength of corroded reinforced concrete beams with large sizes demonstrated good agreement with current and previously published literature data. In the case of corroded beams comprising differing amounts of polypropylene fibers, the performance of the corroded beams was limited by a fiber volume fraction of 1.5% at low corrosion levels.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2017Experimental Study on the Bond Strength of Different Geometries of Corroded and Uncorroded Reinforcement Bars
Yalciner, Hakan; Marar, Khaled
This study develops empirical models for the prediction of the bond strength of uncorroded and corroded reinforcement bars. The effects of hooked reinforcement on the bar's development length when covered fully and partially are examined. An accelerated corrosion method is used to corrode the reinforcement bars embedded in concrete specimens. Pull-out tests are performed to investigate the ultimate bond strength of the concrete specimens. The effects of two different geometries of reinforcement bars are discussed by considering two different concrete strength levels and concrete cover depths. It is found that partly covered hooked reinforcement bars increase the radial stress on the concrete surface and reduce the bond strength. Increases in the bond strength due to the increased roughness of the steel bar caused by the confined corrosion products are less for hooked bars. The results reveal that the developed models show good relationships with the experimentally computed test results.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2015Seismic Performance Assessment of a Corroded 50-Year-Old Reinforced Concrete Building
Yalciner, Hakan; Sensoy, Serhan; Eren, Ozgur
Deterioration due to corrosion becomes a more serious problem when future earthquakes with unpredicted intensity and time are considered. Therefore, the prediction of performance levels of corroded reinforced concrete structures is important to prevent serious premature damage. In this study, a corroded, 50-year-old high school building was analyzed by considering corrosion effects and is presented here as a case study. The relevant data obtained from the structure were used to predict its performance level for different time periods by combining two major effects of corrosion. Deformation due to bond-slip relationships and loss in cross-sectional areas of reinforcement bars were examined as a function of corrosion rate for five corrosion levels. Plastic hinges were defined as a consequence of corrosion effects, and they were used to perform nonlinear push-over analyses. Incremental dynamic analysis was then performed for 20 individual earthquake ground motion records to predict the structure's time-dependent performance levels as a function of corrosion rate. Results showed that corrosion had a serious effect on the performance levels of the school building considered in this study by decreasing bond strength. (C) 2015 American Society of Civil Engineers.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2014Structural response to blast loading: The effects of corrosion on reinforced concrete structures
Yalciner, Hakan
Structural blast design has become a necessary part of the design with increasing terrorist attacks. Terrorist attacks are not the one to make the structures important against blast loading where other explosions such as high gas explosions also take an important place in structural safety. The main objective of this study was to verify the structural performance levels under the impact of different blast loading scenarios. The blast loads were represented by using triangular pulse for single degree of freedom system. The effect of blast load on both corroded and uncorroded reinforced concrete buildings was examined for different explosion distances. Modified plastic hinge properties were used to ensure the effects of corrosion. The results indicated that explosion distance and concrete strength were key parameters to define the performance of the structures against blast loading.
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