• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.883-891
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• 2002

The chloride penetration in concrete structures is influenced by many factors such as types of cement and admixture proportion. Therefore, the effects of these factors on chloride diffusion must be correctly considered. The conventional diffusion analysis also neglected the existence of reinforcing bar in concrete structures. The purpose of the present paper is therefore to investigate the effect of reinforcing bar on the chloride diffusion in concrete structures. For this purpose, a comprehensive finite element analyses have been conducted to obtain chloride penetration profile. The results indicate that the chlorides are accumulated in front of a reinforcing bar and that the accumulation is much larger for the case of large diameter bars. The higher accumulation of chloride at bar location causes much faster corrosion of reinforcing steel. It can be concluded from the present study that the effects of reinforcing bars must be considered in chloride diffusion analysis for more realistic prediction of durable life of concrete structures.

• Magazine of the Korea Concrete Institute
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• v.4 no.3
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• pp.113-121
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• 1992

본 논문에서는 철근콘크리트 부재의 뽐힘부착거동을 규명하기 위하여 일련의 포괄적인 실험 및 이론 연구를 수행하였다. 실험의 주요변수는 콘크리트의 압축강도, 철근간격 및 덮개, 그리고 철근의 부착길이 등을 선정하였다. 본 연구결과 철근 콘크리트의 부착강도는 뿐만아니라 부착길이, 철근의 덮개 등에 따라 큰 영향을 받는 것으로 나타났으며, 본 연구에서는 이들의 영향을 정량적으로 도출하였다. 또한, 본 연구에서는 철근콘크리트의 부착강도식을 새롭게 제안하였으며, 부착응력-슬립관계식도 유도하여 제시하였다.

• Explosives and Blasting
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• v.23 no.2
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• pp.45-56
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• 2005

In this study, fracture formation and fracture volume by blasting demolition of model reinforced concrete pillars were compared with various vertical load and influence of reinforced steel bar. The more vertical load increased, the more tensile cracks and vertical direction cracks produced. In vertical load of 2.0ton, tensile cracks on vertical direction were predominantly produced. Generally, the more vertical load increased, the more bending deformation of concrete steel bar decreased. As a result, vertical load was influenced fracture formation of concrete and bending deformation of reinforced steel bar. Reinforced steel bar was influenced fracture volume of concrete. According to vertical load and influence of reinforce steel bar by blasting demolition of reinforced concrete pillars, drilling and blasting pattern may be modified.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.97-100
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• 2008

Subjected to seismic action causing large deformation of bridge columns, the plastic hinge region is commonly formed in the column end zone. The deformation capacity of a concrete column can be expressed by using plastic hinge length. The mechanical properties of high-strength reinforcing steel is different from that of normal-strength steel and the mechanical properties of steel will influence the plastic hinge formation. Therefore, in other to accurately predict the deformation of concrete column using high-strength steel, the plastic hinge length can be expressed as a function of the mechanical properties of steel such as the tensile to yield strength ratio and the strain at ultimate state. However, little research has been conducted into the effect of mechanical properties of steel on the plastic hinge length. It was difficult to measure the plastic hinge length from the test results. Therefore, the plastic hinge length of concrete columns was investigated from the curvature profile. A numerical approach was used to study the effect of various parameters on plastic hinge length. Based on the results of the numerical parametric study, a new expression for plastic hinge length was proposed.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.299-306
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• 2014

Coating is one of the methods used to solve the problem of corrosion of reinforcement in concrete structures. There are few research reported in the literature regarding the effect of zinc-coating on flexural behavior compared to epoxy coating. The objective of this study was to determine whether zinc-coated rebar adversely affects flexural behavior. Concrete beams reinforced with black or zinc-coated steel were tested in flexure. The test variables included the presence of rebar surface coating with zinc, steel ratio used and cover depth. The study concentrated on comparing crack pattern, crack width, deflection and strain. The ultimate flexural capacity of beams reinforced with zinc-coated bars was not different from that of black steel reinforced beams. The results from deflection and crack width measurements were indicative of no significant variation for the different rebar surface conditions. In addition, it was found that load-strain curve of beam reinforced with zinc-coated steel was similar to that of beam reinforced with zinc-coated steel. Therefore, the test results indicated that the use of zinc-coated rebar had no adverse effect on flexural behavior compared to the use of black rebar.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.81-82
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• 2009

The purpose of this study is to evaluate the influence that shape of tie has on the ductility of reinforce concrete rectangular column with experiment. There is the standard of the shape and arrengement of tie bar for RC column, but nevertheless currently a tie used in some fields under construction has been constructed in different way from the design for the convenience of construction. A research was required to analyze the problem on the behavior of RC column caused from a shoddy and fault construction of tie, and then evaluate the safety.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.795-803
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• 2004

To prevent the shear failure that occurs abruptly with no sufficient warning, the minimum amount of shear reinforcement should be provided to reinforced concrete(RC) beams. The minimum amount of shear reinforcement of RC beams is influenced by not only compressive strength of concrete but also shear span-to-depth ratio and ratio of tensile longitudinal reinforcement. In this paper, 14 RC beams were tested in order to observe the influences of shear span-to-depth ratio, ratio of tensile longitudinal reinforcement, and compressive strength of concrete. The test results indicated that the rate of shear strength to the diagonal cracking strength of RC beams with the same amount of shear reinforcement increased as the ratio of tensile longitudinal reinforcement increased, while it decreased as the shear span-to-depth ratio increased. The observed test results were compared with the calculated results by the current ACI 318-02 Building Code and the proposed equation.

• Journal of the Korea Institute of Building Construction
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• v.23 no.5
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• pp.519-526
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• 2023

This research endeavors to explore the nuances in apparent resistivity readings in concrete specimens due to the proximity of embedded reinforcement. To systematically gauge this, concrete samples incorporating singular and paired rebars were meticulously crafted. These rebars were strategically positioned at intervals of 0.03m, 0.04m, and 0.05m from each specimen's midpoint. Subsequent resistivity assessments were conducted at 0.01m increments up to the predetermined rebar location for each sample. A consistent observation was the nadir in apparent resistivity manifesting at the rebar's epicenter. Notably, dual-rebar configurations registered lower resistivity values at this central juncture compared to their single-rebar counterparts. This metric underscores the palpable impact of surrounding reinforcement on resistivity readings. Further, as the spatial separation between rebars increased, the distinctness in their locational identification via resistivity became increasingly pronounced.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.136-143
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• 2015

Galvanizing is one of the method used to solve the problem of corrosion of reinforcement in concrete structures. There few research reported in the literature regarding the effect of galvanized coating on the behavior of lap splices in concrete beams. The objective of this study was to determine whether galvanized rebar adversely affects lap splice behavior and bond strength. Concrete beams reinforced with black or galvanized rebar were tested in flexure. The test variables included the presence of galvanized rebar steel diameter, and lengths of lap splices. The study concentrated on comparing crack, failure pattern, and bond strength. The ultimate behavior of beams reinforced with galvanized rebar was not significantly different from that of black steel reinforced beams. Therefore, the test results indicated that the use of galvanizing-coated rebar had no adverse effect on behavior in lap splices of rebar compared to the use of black rebar.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.476-483
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• 2023

The present study concerns modelling the structural behaviour for concrete structure into the crack initiation at corrosion of steels. The degradation source included the axial load and steel corrosion. A development of the rust formed on the steel surface was considered with the interfacial gap between steel and concrete. As a result, the tensile damage could occur on the surface of concrete into the cracking with no steel corrosion, which could be further developed by the increasing rust formation, while the cracking at the steel-concrete interface was mainly attributed to the compressive deformation, being restricted within the interfacial zone.