• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.345-352
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• 1998

Compressive strength of concrete compression members strengthend with carbon fiber laminate(CFL) were studied from the test results. Test parameters are spacing, thickness, width, ply and spliced length of carbon fiber laminates. Specimens strength with sheets failed with sudden tensile rupture of the laminate, which indicate very brittle failure mode. Test result shows that closer spacing and to increas thickness of CFL is more effective. But strengthening ratio with 1-ply CFL is more effective than that of specimen with 2-ply CFL. Compressive strength capacity of specimen splied 24cm shows almost similar strength to that of non-spliced specimen. The ultimate load carrying of specimen strengthened with CFL ranges 1.11~1.86 times of that of non-strengthened specimen.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.615-618
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• 2011

최근 건설공사에서 많은 물량이 투입되는 기초구조의 자재비 및 원가절감을 위해 여러 가지 기초구조시스템이 개발되고 있으나, 보편적으로 현장에 적용하기에는 다소 무리가 있는 것으로 지적받고 있다. 본 연구는 강판을 ㄷ자형으로 절곡한 기초전단보강시스템을 개발하기 위한 해석적 연구의 일환으로 진행되었다. 현행 전단머리 보강식에서는 기초판에 대한 전단내력 산정을 위한 기준식이 마련되어 있지 않으며 플랫플레이트 슬래브의 기준식에 따르도록 되어져있다. 그러나 기초판은 지반에 지지되는 구조물로 플랫플레이트 슬래브와는 경계조건이 다르다. 따라서 본 연구에서는 지반에 지지된 경우와 플랫플레이트 슬래브와 같이 모멘트 제로지점을 단순지지한 형태로 기초구조물을 모델링하여 해석을 실시하였다. 해석프로그램은 유한 요소기법이 적용된 ABAQUS를 사용하여 두 지지조건의 차이가 구조물에 미치는 영향을 비교분석하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.1-6
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• 2021

Concrete structures gradually age due to deterioration of materials or excess loads and environmental factors, and their performance decreases, affecting the usability and safety of structures. Although external tension construction methods are widely used among the reinforcement methods of old bridges, it is insufficient to identify the effects and effects of reinforcement depending on the level of aging. Therefore, in this study, a four-point loading experiment was conducted on the subject with the non-reinforced and external tensioning method to confirm the reinforcement effect of the external tensioning method, assuming the aging of the structure as a reduction in the compressive strength and tensile reinforcement of concrete, to analyze the behavior of the reinforcement and confirm the reinforcement effect. As a result of the experiment, it was difficult to identify the amount of reinforcement in the extreme condition due to early elimination of the anchorage. Therefore, compliance with the regulations on anchor bolts is required when applying the external tension reinforcement method. Crack load and yield load increased depending on whether external tension was reinforced, but before the crack, the stiffness before and after reinforcement was similar, making it difficult to confirm the reinforcement effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.183-189
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• 2006

When RC structures are repaired or strengthened using FRP, it is required to cure for some Period under certain air temperature and then it is hopeful to avoid detrimental action caused by external vibration sources during that period. Therefore, an effect of repeated loading during Carbon Fiber Sheet(CFS) strengthening Process on the strengthening efficiency is studied through an experiment for a number of RC beams. Experimental results showed that the curing time of 24 hours without any repeated loading after CFS attachment were recommended for 1 ply strengthening, and 12 hours for 2 plies strengthening.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.483-491
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• 2002

This paper summarizes the results of experimental studies concerning the flexural strengthening of reinforced concrete beams by the external bonding of the new reinforcement material, which is composite panel with an advanced fiber sheet bonded on light concrete precast panel. The structural behaviors of strengthened beams are compared with codes in terms of yield load and ultimate load, deflection, flexural stiffness, ductility. Thirty nine large-scale beams were tested experimentally to evaluate the strength enhancement provided by the composite panel. According to the results, it is shown that beams strengthened with composite panel are structurally efficient and that the strength of the strengthened beams are improved comparing with beams strengthened with fiber sheet.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.153-160
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• 2010

The widespread deterioration of concrete structures has required the development of new and innovative materials and technologies for strengthening and repair. Recently Fiber reinforced polymer(FRP) composites have received widespread attention as materials for the strengthening and repair of the deteriorated concrete structures. This paper presents the results of Fire-performance of RC beams strengthened with FRP-Aluminum composit hollow beams. Test results show that the higher-damaged FRP strengthened RC beams are more vulnerable to the fire and decrease the effect of FRP strenthening.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.1-8
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• 2017

An experimental study is needed a reinforcing method for seismic load to apply for RC structures because a lot of earthquakes have frequently happened in the world and those also collapsed infrastructures or damaged human lives. The reinforcing effect of PolyUrea (PU) appeared to be excellent under blast and impact about RC structures. In this study, Stiff Type PolyUrea (STPU) had developed by manipulating the ratio of the components of prepolymer and hardener of PU. And the durability performance evaluation of STPU for deterioration and chemical resistance has been performed. Acid environmental exposure test and ultraviolet (UV) exposure test have been performed as the durability performance evaluation for STPU. Concrete carbonation exposure test and freezing and thawing test for concrete coated with STPU have been performed. The experimental result showed that STPU has high resisting capacity and durability in all tests. Therefore, STPU would be used as seismic reinforcement materials.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.143-150
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• 2022

This paper presents an experimental study on the flexural performance of concrete members strengthened with external steel plates for the purpose of improving seismic performance. In order to strengthen the structure, a strengthening method was applied that wraps the walls and columns with steel members. The partial section of the wall with the longest span in the structure was manufactured in real size and the strengthening effect was confirmed by performing a static load test. As a result of the experiment, it was confirmed that the strengthened section exhibited sufficient flexural performance satisfied to the seismic requirements, but the behavior until failure was not obtained because of actuator capacity. It was confirmed that the strengthened member resists the out-of-plane moment with a composite behavior. It was verified that the stiffness and load carrying capacity of the strengthened member were improved compared to the non-strengthened member by displacement and strain measurements.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.121-124
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• 2008

The purpose of this study is to evaluate the critical strengthening ratio of concrete railroad bridge strengthened with NSM using CFRP plate. The railroad bridge is usually under vibration and impact in service state. Therefore, it is important that the effective strengthening performance must be exhibited under the service loading is acted. To widely apply the NSM method for the concrete railroad bridge in field, it needs that reasonable strengthening parameter such as strengthening ratio has to be investigated and evaluated when the strengthening design is conducted. In this study, to suggest more reasonable strengthening ratio, material and geometrical uncertainty was considered and applied by Monte Carlo Simulation (MSC) technique. Lastly, the critical strengthening ratio of concrete railroad bridge strengthened with NSM using CFRP plate was evaluated by using the limit state function with the target reliability index.

• Composites Research
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• v.25 no.6
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• pp.224-229
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• 2012

The structural performance is degraded in case of embedding the array antenna for reconnaissance and surveillance into the wing skin structures. In this paper, the optimal design for the thickness of composite hat-shaped stiffener which is reinforced embedded array antenna on the simplified composite wing box was conducted. To select the basic shape of hat-shaped stiffener, structural analysis was carry out using the commercial finite element analysis program while changing the web slope and flange length of hat-shaped stiffener. The optimal thickness of the composite hat-shaped stiffeners was determined by using commercial optimization program such as VisualDOC and commercial FEA program with considering stresses and buckling constraints.