HYB(FRP Hybrid Bar) is composite structural material that combines reinforced bar and FRP. HYB has high elastic modulus and after-yield-hardening properties, despite its corrosion resistance and light weight. HYB under development has relatively stable corrosion durability. This study performs fundamental experiments for the long period UV exposed HYB, and carries out pull-out test for the freezing-thawing exposed specimens of ordinary reinforced bar, HYB, and UV exposed HYB. The effect of UV exposure and freezing-thawing did not affect the tensile property and strength of HYB. However, the bond strength reduction on the environment of accelerated corrosion should be considered in further study.

Tensile strength was investigated for hybrid bar (HYB), in this study. HYB is made of both steel reinforcement and glass fiber. Cross section of HYB has a shape in which steel reinforcement wrapped with glass fiber. For the production of HYB, rebar of SD400 class and glass fiber of E class are used as main materials. Vinyl ester resin is used to harden a glass fiber. In order to evaluate for tensile strength of HYB, the direct tensile test was performed about total ten specimens. The length of total specimens is 2,200 mm including the grip. Diameter of HYB according to core diameter was considered as a test variable. Direct tensile test for HYB was performed using a UTM with a capacity of maximum 1,000 kN. Tensile strength and strain were measured for each specimen during the test. From the test results, tensile strength and elastic modulus were 317 ~ 341 MPa, 103 ~ 107 GPa, respectively. Especially, elastic modulus of HYB was improved in comparison with usual GFRP bars such as the Aslan 100 or the V-rod.

During the last two decades, fiber reinforced polymer (FRP) reinforcing bars for concrete structure have been extensively investigated and a number of FRP bars are commercially available. However, major shortcomings of the existing FRP bars are its high initial cost and low elastic modulus compared to conventional steel bars. Because of these reasons, Korea Institute of Civil Engineering and Building Technology (KICT) in Korea has developed the FRP Hybrid Bar which have the concept of material hybridization for concrete structures, especially for marine and waterfront concrete structures. This developed bar is new type material in construction field, verification of long term performance is very important for commercialization. In this paper, verification methodology on long term performance(corrosion, flexural behavior etc) of FRP Hybrid Bar is suggested.

To overcome shortcomings of fiber reinforced polymer (FRP), a hybridized FRP rebar was developed by the authors. This hybrid bar herein called “FRP Hybrid Bar” was fabricated by adopting advantages from two different materials, including glass fiber reinforced polymer (GFRP). Corrosion resistant characteristics of FRP Hybrid Bar were evaluated and the test results were explained in this paper. The use of the alternative reinforcement could allow concrete structures to extend life-span, to save maintenance and repair costs, etc. if the FRP Hybrid Bar was applied to RC structures located in a very corrosive environment, such as marina or harbor areas.

Flexural capacity of a Textile Reinforced Mortar(TRM) was investigated by an experimental study. The test program was accomplished on reinforced concrete(RC) slabs consisted of concrete(average compressive strength of 22.23 MPa) and rebar(strength class of SD400). RC slab had 450 mm and 150 mm in size and 2,600 mm in clear span. Strengthening was accomplished by applying carbon-fiber mesh in layers of mortar. Control slab(unstrengthened) and six slabs strengthened with TRM were fabricated to confirm the reinforcing performance in this study. Test variables considered amount of reinforcement and use of anchorage. As a results, it was validated that the flexural capacity of slabs strengthened with TRM increased from 159.9% to 285.2% according to the amount of TRM compared with unstrengthened slab. Experimental results indicated that there are increase in ductility as well as load carrying and deformation capacities when using multiple layers of textile.

케이블지지 교량 건설의 증가로 인하여 이러한 시설물의 안전 점검에 대한 관심도 점차 증가하고 있다. 케이블지지 교량에서는 주 부재인 케이블의 성능 평가가 필수적으로 이루어져야 함에 불구하고, 기존의 점검 방식으로는 다양한 제한적인 요인 때문에 적절한 점검이 이루어지지 못하고 있는 실정이다. 이러한 문제점을 보완하기 위해 케이블 점검 로봇 제작이 필요하고, 본 연구에서는 기존의 개발된 케이블 점검 로봇의 성능을 향상시켜서 로봇의 운용 효율성을 높이는데 주목적을 두었다. 성능 보완 요소로는 대 구경 케이블(>200mm)에도 적용할 수 있도록 로봇의 가용범위를 조절할 수 있도록 하였으며, 주행능력도 향상시켜 점검의 효율성을 향상시켰다. 케이블의 내부 손상을 점검하기 위해 전자기센서를 탑재하였고, 실내 실험을 통해 다양한 케이블 손상 유형에 따른 손상 검출 시험을 실시하였다. 추가로 현재 공용중인 교량에서 현장 성능평가를 실시하였다. 그 결과로 본 연구에서 개발된 케이블 점검 로봇은 주행속도에서는 ~0.2m/s로 기존의 점검 로봇에 비해 향상 된 주행 능력을 보였으며, 케이블 내부 손상 점검 실험에서는 케이블 손상 부분을 검출을 할 수 있었다. 마지막으로, 케이블 점검 로봇의 현장 검증 실험에서는 실내 실험과 같은 성능을 보이는 것을 확인하였다.

This paper presents a methodology for assessing the old-age level of facilities. In order to evaluate the retirement level, a method of selecting the indicators related to the old age was presented and a method of assessing the old age level through the measures of the selected indicators is suggested to improve the reliability of evaluation results and to develop evaluation algorithm. In the future, it is expected that it will be possible to efficiently manage the old facilities through the convergence of the old- level evaluation method and IoT sensor, big data, and artificial intelligence.

In this study the existing degradation model for the coated steel member is reviewed, and a new model is recalculated with the deterioration index, ‘rusting’ and ‘flaking’ only. In the case of durability evaluation with the two indexes only some considerations are suggested by the comparison of the existing and recalculated degradation model.

This paper presents the assessment of 7-wire strand monitoring using acoustic emission technique for bridges. 7-wire strand is widely used construction materials to provide additional tensile force to bridges. PSC (PreStressed Concrete) bridge and cable-stayed bridge are representatives for such cases. However, as the bridge aging progresses recently, corrosion problems of strand are emerging. For this reason, various NDT (Non-Destructive Test) methods for cable inspection are being studied and applied to the field. One of the NDT methods, acoustic emission technique, is known as an effective technique to detect cable damage and breakage. In this study, to evaluate the applicability of acoustic emission technique to bridges, acoustic emission signals according to presence or absence of the strand were acquired and analyzed by tensile test. As a result, it is considered that the acoustic emission technique will be able to detect corrosion breakage and signs of rupture.

Airborne chlorides, sulfur dioxide and humidity are the most important causes and acceleration factors of corrosion of the steel member. In this study, such acceleration factors are quantified by analysis of reference data about velocity on corrosion for the determination of durability grade of steel member.

The review of the existing facilities inspection guideline reveals that the dam and river facilities are evaluated mainly by visual and safety inspection. For the efficient maintenance it is necessary to inspect the steel member of the dam and river facilities using the performance-based evaluation method throughout quantitative measurement. In this study durability evaluation index of steel member and evaluation method for the facilities is presented.

The review of the existing facilities inspection guideline reveals that the slope is evaluated mainly by visual and safety inspection. For the efficient maintenance it is necessary to inspect the slope using the performance-based evaluation method throughout quantitative measurement. In this study durability evaluation index and evaluation method for the slope is presented.

The correlation between the degradation scores and service life of the coating is derived by tests and inspection for the coated steel member according to each service environment of several facilities. This correlation called to as the deterioration model can be used to determine the performance grade for the durability of coated steel member of facilities under each service environment, for example, atmospheric, fluvial and marine environment.

Numerical analysis was performed to predict for deflection of reinforced concrete (RC) beams in flexure strengthened with textile reinforced concrete (TRC) in this study. TRC is new reinforcing material to strengthen for deteriorated RC structures. TRC consists of fiber reinforced polymer (FRP) reinforcement of textile form and concrete using fine aggregate. This paper presents both results and process of nonlinear analysis method for experimental results published in 2015 by Jung et al. Nonlinear analysis method proposed by Cho et al. was used to predict the displacement at the cross-section of mid-span for RC beams in flexure strengthened with TRC. At the three states of the RC beams such as occurrence of initial flexural crack in tensile concrete, the yield of tensile rebar, and ultimate in accordance with debonding of TRM. Displacements of beams were calculated at the three state and load-displacement curves by predicting results were compared to the collected test results. As a result, nonlinear analysis method accurately predicted the deflection of RC beams strengthened with TRC.

The review of the existing facilities inspection guideline reveals that the water supply steel pipeline is evaluated mainly by visual and safety inspection. For the efficient maintenance it is necessary to inspect the pipeline using the performance-based evaluation method throughout quantitative measurement. In this study durability evaluation index and evaluation method for the steel pipeline is presented.

Numerical analysis was performed to predict for deflection of reinforced concrete (RC) beams in flexure strengthened with textile reinforced concrete (TRC) in this study. TRC is new reinforcing material to strengthen for deteriorated RC structures. TRC consists of fiber reinforced polymer (FRP) reinforcement of textile form and concrete using fine aggregate. This paper presents both results and process of nonlinear analysis method for experimental results published in 2015 by Jung et al. Nonlinear analysis method proposed by Cho et al. was used to predict the displacement at the cross-section of mid-span for RC beams in flexure strengthened with TRC. At the three states of the RC beams such as occurrence of initial flexural crack in tensile concrete, the yield of tensile rebar, and ultimate in accordance with debonding of TRM. Displacements of beams were calculated at the three state and load-displacement curves by predicting results were compared to the collected test results. As a result, nonlinear analysis method accurately predicted the deflection of RC beams strengthened with TRC.

Indices are selected for the evaluation of deterioration of coated steel, and an evaluation method is proposed for each index. The evaluation methods proposed in this study are then applied on the existing inspection data measured on site, and the correlation between the resulting evaluation scores and service life of the coating is derived statistically. This correlation called to as the deterioration model can be used to determine the performance grade for the durability of coated steel.

Shear capacity of a Textile Reinforced Concrete (TRC) was investigated by an experimental study. Control beam (unstrengthened) and eight beams strengthened with TRC were fabricated to confirm the reinforcing performance in this study. Test variables considered the number, width, spacing of TRC, and reinforcing method accordance with type of attachment. As a results, it was validated that the shear capacity of beams strengthened with TRC in comparison with unstrengthened beam increased from 11.4% to 54.3% according to the amount of TRC. Experimental results indicated an increase in both load carrying and deformation capacities, and also ductility when using multiple layers of textile.

SIFCON's mechanical properties were investigated experimently to develop for anchor block. A normal concrete was used to compare with SIFCON. As a result, SIFCON has higher strength and toughness those of normal concrete.

The purpose of this study is to compare and analyze the flexural behavior characteristics of the RC(Reinforced Concrete) beam and the SIFCON(Slurry Infiltrated Concrete) beam. Three-point loading test was progressed about a RC beam and SIFCON beams of 6 according to various heights and with or without tensile reinforcement. As a result, producing structure using SIFCON can reduce weight and the use of steel reinforcement because SR300 shows higher maximum load than Control specimen.