• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.559-568
• /
• 2019

Recently, the infrastructure of the marine environment has been increasing. Therefore, there has been increasing interest in increasing the durability of structures. The FRP Hybrid Bar with improved durability against corrosion was developed in recent years. On the other hand, studies that evaluate the corrosion resistance are insufficient. In this study, the corrosion resistance according to the type of rebar in concrete was assessed and analyzed. The experiment used steel bars and FRP Hybrid Bar. The corrosion test method was a galvanic current and half-cell potential method. The accelerated corrosion test was carried out by four levels (0%, 1.5%, 3%, and 6%) of chloride added to the concrete. The galvanic current measurements revealed no corrosion current in the FRP Hybrid Bar. The half-cell measurement also showed the corrosion resistance of the FRP Hybrid Bar. Therefore. FHB can be used as an alternative steel for structures where a marine environment and steel corrosion are predicted.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.1-13
• /
• 2022

This study aims to investigate the feasibility of the half-cell potential (HCP) measurements on the concrete surface for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete. A series of experimental study is performed to measure HCP (or corrosion potential, E_corr) and corrosion current density (i_corr) of reinforcing steel in concrete cube specimens, with a side length of 200 mm. Various corrosion levels in a range of 0% to 20% of the test specimens are accelerated by impressing current to the reinforcing steel in concrete immersed in 3.0 % NaCl solution. HCP is measured in accordance with ASTM C876-15, and corrosion current density is determined by using the Stern-Geary equation and measured polarization resistance measured by electrochemical impedance spectroscopy (EIS). As a result, a numerical formula that relates HCP and i_corr in the test specimen is established by a regression analysis of the measured data in this study. It is observed that HCP is linearly correlated with log(i_corr) with a R² greater than 0.87, which is less affected by the experimental variables such as concrete mixture proportion, diameter of reinforcing steel and the amount of applied current in this study. These results exhibit that HCP measurements could be effective for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete in the case of exposed to a certain consistent environment.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.3
• /
• pp.215-223
• /
• 2013

An experimental research on the possibility of using fiber reinforced concrete precast tunnel segments instead of traditional reinforced concrete(RC) segment has been performed in europe. This solution allows removing the traditional reinforcement with several advantages in terms of quality and cost reduction. Full-scale bending tests were carried out in order to compare the behaviour of the segments under flexural actions on both rebar reinforced concrete and rebar-fiber reinforced elements. The test results showed that the fiber reinforced concrete can substitute the traditional reinforcement; in particular the segment performance is improved by the fiber presence, mainly in terms of crack.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.5A
• /
• pp.719-727
• /
• 2008

The tensile and bond performance of GFRP rebar are different from those of conventional steel reinforcement. It requires some studies on concrete members reinforced with GFRP reinforcing bars to apply it to concrete structures. GFRP has some advantages such as high specific strength, low weight, non-corrosive nature, and disadvantage of larger deflection due to the lower modulus of elasticity than that of steel. Bridge deck is a preferred structure to apply FRP rebars due to the increase of flexural capacity by arching action. This paper focuses on the behavior of concrete bridge deck reinforced with newly developed GFRP rebars. A total of three real size bridge deck specimens were made and tested. Main variables are the type of reinforcing bar and reinforcement ratio. Static test was performed with the load of DB-24 level until failure. Test results were compared and analyzed with ultimate load, deflection behavior, crack pattern and width.

• Journal of the Korea Concrete Institute
• /
• v.27 no.1
• /
• pp.37-44
• /
• 2015

This paper describes the effect of strain hardening cement composite (SHCC) material on structure performance of reinforced concrete (RC) beams with high-strength reinforcing bar. Also, this paper explores the structure application of SHCC in order to mitigation cracking damage and improve the ductility of flexural RC members. The prediction model for flexural strength of doubly reinforced SHCC beams are investigated in this study. To achieve the these objectives, a total of 6 rectangular beam specimens were tested under four point monotonic loading condition. The main parameters included the types of cement composite and reinforcing bar. Test results indicated that reinforced beam specimens with SHCC material were improved the structure performances and damage characteristics. Specifically, replacement of conventional high-strength concrete with SHCC materials has the potential of high-strength steel bar as flexural reinforcement on RC members. It is remarkable that suggested method of reinforced SHCC beams with high-strength reinforcing bar could be used usefully to the structure design.

• Magazine of the Korea Concrete Institute
• /
• v.6 no.5
• /
• pp.193-202
• /
• 1994

In this study, an equation for modelling the shear strength of reinforced concrete member with web reinforcement is proposed. Although the general formulas for shear strength of reinforced concrete member with small a /d are obtained based on the experimental results, the proposed equation herein is derived from lower bound theorem of limit analysis. The proposed model takes into account arch mechanism and truss mechanism. And ir provides the values of divided shear strength ratio of each mechanism as well as visual understanding of the mechanism on how the given load is transfered to the support. Also, the model takes into account the effect of a /d. longitudinal reinforcement ratio, and web reiriforcement ratio quantitively. Based on the comparisons of the result of this model with previous, test results, it shows good agreements.

• Journal of the Korea Concrete Institute
• /
• v.26 no.3
• /
• pp.255-266
• /
• 2014

This paper investigates the seismic performance of T-shaped PC walls with a new vertical connections and wet cast joint. The load-displacement relationship, strength, ductility, failure mechanism, and deformation capacity of the T-shaped PC walls subjected to cyclic loading are verified. Test parameter is diagonal reinforcement of both flange and web wall panels to transfer shear strength. The longitudinal reinforcing steel bars placed edges of walls yield first and the ultimate deformation is terminated due to premature failure of connections. And diagonal reinforcements for shear transfer in walls are effective to restrain the wall crack. The strength and displacement obtained by the cross section analysis were very similar to the experimental data.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2009.11a
• /
• pp.265-268
• /
• 2009

전기로 산화 슬래그 골재는 철강산업의 부산물을 재활용한다는 측면에서 친환경적일 뿐만 아니라 고갈되고 있는 골재자원을 대체할 수 있다는 측면에서 중요한 가치를 지닌다. 본 연구에서는 다량의 철성분을 함유하고 있어 높은 밀도를 나타내는 전기로 산화슬래그 골재를 사용한 친환경 콘크리트의 횡구속 성능에 관하여 검토하였다. 이 실험에서는 전기로 산화슬래그 굵은 골재 및 잔골재를 적용한 콘크리트 공시체를 제작하여 천연 굵은 골재와 잔골재를 적용한 콘크리트의 횡구속 거동을 파악하였다. 실험변수는 콘크리트 제작에 사용한 골재의 종류, 횡보강에 사용한 나선 철근의 항복강도로 하였다. 실험결과 전기로 산화슬래그 골재를 사용하였을 경우 천연골재를 사용한 실험체와 유사한 횡구속 효과를 보였다.

• Magazine of the Korea Concrete Institute
• /
• v.2 no.4
• /
• pp.53-60
• /
• 1990

Investigations on the behavior of steel fiber reinforced high strength concrete beams with shear confinement are accomplished to determine their ultimate shear strength including diagonal tension strength. The parameters varied were the shear confinement ratio(Ps), and fiber volume fraction(Vs). Ultimate shear strength increased significantly in steel fiber reinforced concrete beam without shear confinement. In steel- fiber reinforced high strength concrete beams with shear confinement, there is no increase of ultimate shear strength but shows much beneficial effects of Ductility Capacity.

• Magazine of the Korea Concrete Institute
• /
• v.5 no.3
• /
• pp.107-115
• /
• 1993

최근 건설공사의 급증으로 인한 하천골재의 고갈로 콘크리트용 대체골재로서 해사\ulcorner선사 등이 대구되고 있다. 그러나 해사는 세척하지 않고 그대로 콘크리트에 사용할 경우 콘크리트중의 철근부식 촉진에 따른 콘크리트의 균열발생 등 조기 노후화현상으로 내구성에 많은 문제점을 내포하고 있고, 산사는 국내 연구실적이 전혀 없는 상태에서 지역적으로 무분별하게 사용되고 있어 이들에 관한 제반 공학적 특성 및 활영방안 연구가 시급한 실정이다. 따라서 본 연구는 산사\ulcorner해사를 사용한 콘크리트의 압축강도 특성 및 해사의 염분함량과 콘크리트의 물-시멘트비에 따른 철근부식량과의 관계를 구명하였다.