• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.175-176
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• 2023

The masonry structure is constructed by cement mortar binding material of brick objects and uses reinforced hardware(connected hardware or wall tie) together when building. However, over time, the corrosion of reinforced steel and the deterioration of joint mortar as well as bricks cause the risk of collapse. In particular, when the externally decorated brick wall is installed on the concrete girder for each floor, the angle bracket is not constructed or corroded, the full-layer weight load is applied to the wall of 0.5B, which is an example of full-scale or collapse. As a result of the evaluation, it was confirmed that the performance was improved compared to the existing bracket, and we plan to carry out a real-life test and long-term performance review of the building using the bracket in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.110-118
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• 2008

The use of FRP bar as reinforced concrete beams is considered as one of the most prominent solution that may overcome the corrosion of reinforcing steel bars. However, in the case of FRP reinforced concrete, both the reinforcing and the reinforced materials are brittle. For this reason, ductility of structures with FRP reinforcement is much less than that of structures with steel reinforcements. In this study, a method has been suggested to provide a meaningful quantification of ductility for concrete beams reinforced with FRP bars. This paper shows which the confinement to the compression concrete by the spiral can increase the ductility of FRP over-reinforced concrete beams.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.13-16
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• 2008

Corbels are short cantilevers that project from the faces of a column and are a type of stress disturbed member, resisting both the ultimate shear force applied to them by the beam, and the ultimate horizontal force caused by shrinkage, temperature changes, and creep of the supported elements. Recently, as there have been an increase in the use of high-strength concrete and the concern about corrosion problems, lots of researches about hybrid reinforcing technique, applying strategically high performance reinforcements to the concrete elements, are performed. In this study, fiber reinforced high strength concrete corbels were constructed and tested for applying hybrid reinforcing technique to the corbels using steel fibers and headed bars. The results showed that the performance in terms of load carrying capacities, stiffness, ductility, and crack width was improved, as the steel fibers were added and the percentage of steel fibers was increased. In addition, the corbel specimens used headed bars as main tension ties showed superior load carrying capacities, stiffness, and ductility to the corbel specimens anchored main tension ties by welding to the transverse bars.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.73-81
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• 2002

Nowadays , the grouted-reinforcing method, which is called FRP(Fiberglass-reinforced-plastic) pipe .reinforcing method, has been introduced in the community of pound reinforcements. The resistance to corrosion and chemical attack high strength to weight ratio, and ease of handling make these pipes a better alternative to steels in tunnel. However, to fully utilize FRP pipes as grouted reinforcing members at the face and the crown in tunnel, their mechanical properties and behaviors and the grout-reinforced underground have to be verified. Laboratory shear tests were conducted to evaluate the mechanical properties for FRP pipes, the grout-reinforced members and the grout-reinforced body of FRP pipes. According to the test results, it was observed that FRP pipes play a dominant role in shearing behavior of the grout-reinforced members and that their shearing resistance exerts after the shearing displacement increases to some extent.

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.562-569
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• 2017

Reinforced concrete is used for bridges and large structures that are constructed with social overhead capital because they are economically and semi-permanently integrated with reinforcing bar and concrete. However, when the chloride ion in the concrete destroys the passive film of the reinforcing bar by the marine exposure environment and the snow remover used in the winter season, and the reinforcing bar is corroded by various chemical and physical actions, the durability is deteriorated in a short period, and the life span is shortened. In this study, a repair method to recover the durability of the initial structure by effectively removing chloride ion from the damage caused by salting of the above mentioned reinforced concrete was conducted.

• Journal of the Korea Institute of Building Construction
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• v.12 no.3
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• pp.275-283
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• 2012

Nitrite-type hydrocalumite (calumite) is a material that can adsorb the chloride ions ($Cl^-$)that cause the corrosion of reinforcing bars and liberate the nitrite ions ($NO_2{^-}$) that inhibit corrosion in reinforced concrete, and can provide a self-corrosion inhibition function to the reinforced concrete. In this study, VA/E/MMA-modified mortars with calumite were prepared with various calumite contents and polymer binder-ratios, and tested for corrosion inhibition, chloride ion penetration, carbonation and drying shrinkage. As a result, regardless of polymer-binder ratio, the replacement of ordinary Portland cement with hydrocalumite has a marked effect on the corrosion inhibiting property of the polymer-modified mortars. However, chloride ion penetration and carbonation depths are somewhat increased with higher calumite content, but can be remarkably decreased depending on the polymer-binder ratios. The 28-d drying shrinkage shows a tendency to increase with the polymer-binder ratio and calumite content. VA/E/MMA-Modified mortars with 10 % calumite did not satisfy KS requirements. Accordingly, a calumite content of 5 % is recommended for the VA/E/MMA-modified mortars with calumite.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.4
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• pp.203-214
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• 2023

In this study, the physical properties and fracture characteristics according to the tensile load are evaluated on the materials of the polymeric filler and carbon fiber-based composite sleeve technique. The polymeric filler and the composite sleeve technique are applied to areas where the pipe body thickness is reduced due to corrosion in large-diameter water pipes. First, the tensile strength of the polymeric filler was 161.48~240.43 kg_f/cm², and the tensile strength of the polyurea polymeric filler was relatively higher than that of the epoxy. However, the tensile strength of the polymeric filler is relatively very low compared to ductile cast iron pipes(4,300 kg_f/cm²<) or steel pipes(4,100 kg_f/cm²). Second, the tensile strength of glass fiber, which is mainly used in composite sleeves, is 3,887.0 kg_f/cm², and that of carbon fiber is up to 5,922.5 kg_f/cm². The tensile strengths of glass and carbon fiber are higher than ductile cast iron pipe or steel pipe. Third, when reinforcing the hemispherical simulated corrosion shape of the ductile cast iron pipe and the steel pipe with a polymeric filler, there was an effect of increasing the ultimate tensile load by 1.04 to 1.06 times, but the ultimate load was 37.7 to 53.7% compared to the ductile cast iron or steel specimen without corrosion damage. It was found that the effect on the reinforcement of the corrosion damaged part was insignificant. Fourth, the composite sleeve using carbon fiber showed an ultimate load of 1.10(0.61T, 1,821.0 kg_f) and 1.02(0.60T, 2,290.7 kg_f) times higher than the ductile cast iron pipe(1,657.83 kg_f) and steel pipe(2,236.8 kg_f), respectively. When using a composite sleeve such as fiber, the corrosion damage part of large-diameter water pipes can be reinforced with same level as the original pipe, and the supply stability can be secured through accident prevention.

• Computers and Concrete
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• v.6 no.3
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• pp.235-252
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• 2009

Due to the reduction of bond strength resulting from the high corrosion level of reinforcing bars, influence of this reduction on flexural capacity of reinforced concrete (RC) beam should be considered. An extreme case is considered, where bond strength is complete lost and/or the tensile steel are exposed due to heavy corrosion over a fraction of the beam length. A compatibility condition of deformations of the RC beam with partially unbonded length is proposed. Flexural capacity of this kind of RC beam is predicted by combining the proposed compatibility condition of deformations with equilibrium condition of forces. Comparison between the model's predictions with the experimental results published in the literature shows the practicability of the proposed model. Finally, influence of some parameters on the flexural capacity of RC beam with partially unbonded length is discussed. It is concluded that the flexural capacity of the beam may not be influenced by the completely loss of bond of the whole beam span as long as the tensile steel can yield; whether or not the reduction of the flexural capacity of the beam resulting from the loss of bond over certain length may occur depends on the detailed parameters of the given beam.

• Structural Engineering and Mechanics
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• v.49 no.2
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• pp.203-223
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• 2014

The extensive use of prestressed reinforced concrete (PSC) highway bridges in marine environment drastically increases the sensitivity to both fatigue-and corrosion-induced damage of their critical structural components during their service lives. Within this scenario, an integrated method that is capable of evaluating the fatigue reliability, identifying a condition-based maintenance, and predicting the remaining service life of its critical components is therefore needed. To accomplish this goal, a procedure for fatigue reliability prediction of PSC highway bridges is proposed in the present study. Vehicle-bridge coupling vibration analysis is performed for obtaining the equivalent moment ranges of critical section of bridges under typical fatigue truck models. Three-dimensional nonlinear mathematical models of fatigue trucks are simplified as an eleven-degree-of-freedom system. Road surface roughness is simulated as zero-mean stationary Gaussian random processes using the trigonometric series method. The time-dependent stress-concentration factors of reinforcing bars and prestressing tendons are accounted for more accurate stress ranges determination. The limit state functions are constructed according to the Miner's linear damage rule, the time-dependent S-N curves of prestressing tendons and the site-specific stress cycle prediction. The effectiveness of the methodology framework is demonstrated to a T-type simple supported multi-girder bridge for fatigue reliability evaluation.

• Magazine of the Korea Concrete Institute
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• v.13 no.5
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• pp.77-81
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• 2001

부식 열화는 교량 기술자들에게 있어서 지속적인 도전을 요구하는 문제가 되어왔는데, 스텔스 항공기를 개발하게 한 새로운 재료 기술은 교량의 부식을 해결할 수 있게 하였다. 즉, 경량의 고강도 재료로 높은 피로 저항성을 갖고 있고, 부식에 강한 복합체는 교량의 재료로서 아주 바람직한 성질을 갖고 있다 섬유 보강 폴리머(FRP) 복합재료를 교량의 건설에 이용하려는 프로젝트는 1998년 현재 80 여 개가 넘게 진행되고 있는데, 이 중 미국 내에서 31개의 프로젝트가 수행되고 있다. 이 글은 미국 내에서 FRP복합체를 교량 공학 분야에 적용하려는 초기의 성공적인 시도들에 관한 내용으로 복합체의 장점, 특성, 교량 적용시 고려 사항, 그리고 향후 복합재료에 관한 기술을 토목 구조물에 적용하는데 필요한 소요 기술 등에 관하여 정리한 것이다. 이 새로운 재료는 신설 구조물의 건설과 기존 교량의 보수 및 보강에 모두 적용할 수 있으며, FRP복합체 기술을 토목 구조물과 기반 시설물 건설 분야에 적용하는 것은 지금까지 성공적인 결과를 보여 주고 있다 미국연방도로국(FHWA, Federal Highway Administration)은 이 기술을 미국 내 교통 기반 시설물인 신규 교량의 건설은 물론 기즌 교량의 보수 및 보강에 활용하는 방안에 대하여 관심을 갖고 있다.