• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.38-44
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• 2012

This paper presents experimental studies aiming at evaluation of structural behaviors of RC (Reinforced Concrete) beams externally strengthened with taper ended CFRPs(Carbon Fiber Reinforced Polymers). Experiments are performed with RC beams having different numbers of CFRP layers and length of each layer. The beams are subjected to four point-bending with simply supported condition. Test results of taper ended CFRPs and non-tapered CFRPs are compared and the better strengthening effect is observed from tapered ended CFRPs.

• Computers and Concrete
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• v.5 no.6
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• pp.545-558
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• 2008

The corrosion of RC structures demonstrates very complicated forms of deterioration intermingled together but all pointing to a decrease in the durability of RC structures due to the corrosion of reinforcing bars. Until now, nondestructive techniques, such as half-cell potential and polarization resistance, have been widely available in the world. The former provides information on the probability of corrosion while the latter is associated with information concerning corrosion rates. Inversion by the boundary element method (IBEM) was developed for considering concrete resistivity. The applicability of the procedure was examined through a numerical analysis and electrolytic tests for RC slabs. A distribution in such concrete resistivity is relatively inhomogeneous including cracks on the surface of slabs. Regarding cracks in concrete, the relative coefficient of concrete resistance was introduced to perform its analysis. Further, the procedure will be developed to identify the corroded region visually using 3-D VRML.

• Computers and Concrete
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• v.4 no.4
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• pp.285-298
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• 2007

Corrosion of Reinforcement (rebar) is nondestructively estimated by the half-cell potential measurement. As is the case with other nondestructive testings (NDT), understanding of the underlying principles should be clarified in order to obtain meaningful results. Therefore, the measurement of potentials in concrete is analytically investigated. The effect of internal defects on the potentials measured is clarified numerically by the boundary element method (BEM). Thus, a simplified inversion by BEM is applied to convert the potentials on concrete surface to those on rebars, taking into account the concrete resistivity. Because the potentials measured on concrete surface are so sensitive to moisture content, concrete resistivity and surface condition, an inverse procedure to convert the potentials on concrete surface into those on rebars is developed on the basis of BEM. It is found that ASTM criterion is practically applicable to estimate corrosion from the potential values converted. In experiments, an applicability of the procedure is examined by accelerated corrosion tests of reinforced concrete (RC) slabs. For practical use, the procedure is developed where results of IBEM are visualized by VRML (Virtual Reality modeling Language) in three-dimensional space.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.3
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• pp.157-162
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• 2005

In order to evaluate the corrosion of reinforcing steel-bars (rebar) in concrete, a nondestructive evaluation by the half-cell potential method is currently applied. In this study, potentials measured on a concrete surface are compensated into those on the concrete-rebar interface by the inverse boundary element method (IBEM). Because these potentials are obtained three-dimensionally (3-D), 3-D visualization is desirable. To this end, a visualization system has been developed by using VRML (Virtual Reality Modeling Language). As an application, results of a reinforced concrete (RC) slab with corroded rebars are visualized and discussed.