• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.152-157
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• 1994

Due to the recent shortage of river sand resulting from a rapid growth of concrete construction, sea sand is increasingly used in stead. It is, however, well noted that non-washed sea sand used in reinforced concrete causes to corrode reinforcing steel and to incur cracks in concrete, and thus eventually result in damage to concrete. In this study, therefore, measeres that increase the quality of concrete were used to protect the reinforcing steel against corrosion in reinforced concrete construction, and then the corrosion resistance of reinforcing steel compared and analyzed from low quality concrete to high quality concrete.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.827-832
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• 2003

This study presented the reinforcing effect of sands by using newly devised 3D Tirecell. Plate loading tests for sand were conducted for different relative density and number of reinforced layers. From the tests, the ultimate bearing capacity of reinforced sand increased with increasing relative densities. The effect of reinforced layers with 0.4B interval is limited to 2 layers and further reinforcing effects can not be obtained beyond 3 layers. Especially the bearing capacity increased remarkably at 1 layer of Tirecell reinforcement and the degree of increase was small for 1 layer to 2 layers increase of reinforcement. Test results show that the reinforcing effect of Tirecell is prominent compared with commercial geocell in the literature.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.17-22
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• 1991

An accurate and efficient analytical model describing the bond effect between reinforcing steel and concrete without taking the double nodes is presented. To increase the efficiency of the solution and reduce the number of degrees of freedom, the reinforcing bar elements are considered to be embedded in the connote elements. Relative douses of freedom accounting for the relative slip between reinforcing steel and concrete are condensed out during the stiffness formation phase. However, these degrees of freedom Can be taken into account explicitly by solving the constructed global equilibrium equation for each reinforcing steel. The usefulness of proposed model is established through the comparison with the experimental data subjected on push and push-pull loadings.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.345-350
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• 2001

Reinforced concrete is, in general, known as a high durability material due to a strong alkalinity of cement. Probable concrete cracks could incur steel corrosion of RC structures and then could easily deteriorate the concrete durability, which can be fully secured by a systematic quality control for the construction of concrete structures. For the corrosion protection of reinforcing steels in concrete, however, current design specifications of concrete cover depth do not in-depth consider the effect of the cracks as well as the chloride content of RC structures. Therefore, appropriate provisions for concrete cover depth should be coded by considering the influence of concrete cracks on the corrosion of reinforcing steels. The objective of this research is to investigate pertinent cover depth, which can prohibit rebar corrosion, on the basis of experimental corrosion measurements of reinforcing steels on crack characteristics such as the width, depth and frequency of concrete cracks.

• KCI Concrete Journal
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• v.13 no.2
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• pp.67-74
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• 2001

In this study, a numerical model for the simulation of reinforced concrete columns subject to cyclic loading is presented. The model consists of three separate models representing concrete, reinforcing steel bars and bond-slip between a reinforcing bar and ambient concrete. The concrete model is represented by the plane stress plastic-damage model and quadrilateral finite elements. The nonlinear steel bar model embedded in truss elements is used for longitudinal and transverse reinforcing bars. Bond-slip mechanism between a reinforcing bar and ambient concrete is discretized using connection elements in which the hysteretic bond-slip link model defines the bond stress and slip displacement relation. The three models are connected in finite element mesh to represent a reinforced concrete structure. From the numerical simulation, it is shown that the proposed model effectively and realistically represents the overall cyclic behavior of a reinforced concrete column. The present plastic-damage concrete model is observed to work appropriately with the steel bar and bond-slip link models in representing the complicated localization behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.185-192
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• 1999

This paper presents the results of a parametric study on the behavior of tunnel face reinforced with horizontal pipes. A three-dimensional finite element model was adopted in this study to capture the three-dimensional nature of tunnel face behavior under various boundary conditions. A parametric study was peformed on a wide range of boundary conditions with emphasis on the effect of reinforcing layouts on the deformation behavior of tunnel face. The results of analysis such as tunnel face deformation behavior under various conditions were thoroughly analyzed, and a database for the behavior of tunnel face under different reinforcing conditions was established for future development of a semi-empirical design/analysis method for the tunnel face reinforcing technique. The results indicated that there exits an optimum reinforcing layout for a given tunnel condition, which must be selected with due consideration of tunnel geometry and ground condition.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.195-196
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• 2012

Because of the high level of the safety and durability, a lot of reinforcing bars is placed in the concrete structure of the Nuclear Power Plant. But the overcrowding re-bars cause some problems during the construction as the diseconomy, construction delay, quality deterioration, and so on. These problems can be solved by applying the high-strength reinforcing bars to NPP structure. To achieve this, after analysing the structural target performance like the control of cracks, adherence, shear, torsion, development of reinforcement and earthquake-resistance, the results of the analysis will be reflected in the structural performance evaluation test.

• Composites Research
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• v.18 no.4
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• pp.59-65
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• 2005

This report is on the Reinforcing System(MFRI) for Concrete Structure using FRP ROD & High-Performance Mortar. The main characteristic of this system is as follow. First, the fiber rods in this system have seven times greater tensile strength than general reinforcing steel bars(re-bar) and the weight is a fifth lighter. Camels coated on the fiber rods' surfaces to improve adhesive strength and pull-out strength. Second, high strength shotcrete mortar is has very good workability and low rebound rate. After installing the Fiber Rods, Shotcrete mortar Is applied or sprayed to finish reinforcement. Finally, MFRI system has excellent fire-resisting performance and sogood tolerance against external environment by inserting fiber rods and reinforcing materials into mortar which has high compressive strength. It is applied to bridge slab, utility box and tunnel of civil engineering works, and beam and slab of building structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.543-548
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• 2001

The corrosion monitoring methods of reinforcing steel in concrete are the various methods such as half cell potential method, galvanic current method, resistivity method, polarization resistance method, AC impedance method and etc. In this study, the corrosion monitoring methods of reinforcing steel in concrete were investigated for the test specimens using corrosion inhibitors, zinc-mortar, zinc-plate, respectively. For this purpose, the accelerated corrosion tests for reinforcing steel were conducted according to the periodic cycles(140 days) of wetting($65^{\circ}C$, 90% R.H.) and drying period(15$^{\circ}C$ , 65% R.H.) for the test specimens. As a result, it can be concluded from the test that half cell potential and galvanic current method as monitoring techniques for corrosion were found to be relatively reliable and easily usable method in the field.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.116-119
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• 2004

The use of higher strength materials frequently requires the change of design provisions. Following to the previous researches, high strength reinforcing bars have a weak point about the development and splice length. Based on the previous research about high relative rib area, bond strength between reinforcing bars and concrete can be improved by the control of rib height and spacing. But, the code provisions do not include these specific shape of reinforcing bars. So, the purpose of this paper is to determine the effect of relative rib area to the bond strength. This paper describes the experiment and analysis of 5 beam-spliced specimens containing D25 with relative rib areas ranging from 0.073 to 0.17. The test results are also analyzed to make a design formula about the calculation of splice length on the consideration of relative rib area.