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FRP로 보강된 R/C 보의 휨내력 향상효과에 관한 실험연구
하상수,이용택,이리형 대한건축학회 1999 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.19 No.2
The purpose of this study is to evaluate the structural performance of the new reinforcement material, which has been developed by REFORM system. The carbon fiber sheet is susceptible to fire and brings the concern for the integration. The new reinforcement material was developed to overcome these problems of the carbon fiber sheet. The experiment was planned to evaluate the effect of reinforcement and integration for the new reinforcement material. The theoretic values of test specimens, which are being built, are compared with the experimental values of carbon fiber sheet and the expected effects are commented in the appendix. The experimental values of the specimens will lie compared with the theoretic values after the experiment.
하상수,김태수 국제차세대융합기술학회 2023 차세대융합기술학회논문지 Vol.7 No.12
본 연구는 압축을 받는 사각부재의 표면에 섬유보강재로 보강했을 때, 횡보강에 의한 구속효과를 파악하기 위해 실험적 연구를 수행하였다. 보강에 사용된 섬유보강재는 바잘트섬유(Basalt fiber)와 PEN섬유(Polyethylene Naphthalate fiber)이다. 바쟐트섬유는 2겹, 4겹, 6겹으로 보강하였으며, PEN섬유는 1겹, 2겹, 3겹으로 보강하였다. 150mm x 150mm인 정사각형 단면이며, 높이는 300mm로 계획하였다. 실험결과, 바잘트 섬유 및 PEN 섬유로 보 강한 실험체는 파괴시 취성파괴가 발생하지 않고, 초기 최대강도 이후 강도가 다소 감소하는 경향을 보이다가 다 시 강도가 상승하는 경향을 보여주어 연성이 크게 증가하였다. In this study, an experimental study was conducted to understand the lateral constraint effect by transverse reinforcement when reinforcing with fiber reinforcement on the surface of a square member. The fiber reinforcement materials used for test specimens are basalt fiber and polyethylene Naphthalate fiber. Basalt fiber was reinforced with two layers, four layers, and six layers, and PEN fiber was reinforced with one layer, two layers, and three layers. It is a square cross-section with 150mm x 150mm, and the height was planned to be 300mm. As a result of the experiment, the experiment reinforced with bazalt fiber and PEN fiber showed no brittleness destruction during destruction, and the strength tended to decrease slightly after the initial maximum strength, and then increased the strength again, resulting in a significant increase in ductility.
하상수 대한건축학회 2022 대한건축학회논문집 Vol.38 No.9
An experimental study was conducted with the type and reinforcement amount of fiber roving as variables in order to understand the bending performance of mortar thin plate members reinforced with fiber roving. The ultimate purpose of the experiment is to determine whether a mortar thin plate member can be manufactured and whether fiber roving distributed in the thin plate member can serve as a tensile material. As a result of the study, the fiber roving distributed in the thin mortar plays a sufficient role as a tensile reinforcing material, and the theoretical and experimental equations are compared based on the basic bending theory, and the two values are relatively well matched. 섬유로빙으로 보강한 모르타르 박판부재의 휨성능을 파악하기 위해 섬유시트로빙의 종류 및 보강량을 변수로 하여 동일한 실험체를 제작하고 실험적 연구를 진행하였다. 실험의 궁극적인 목적은 모르타르 박판부재의 제작이 가능한지의 여부와 박판부재 속에 배근되어 있는 섬유로빙이 인장재로서의 역할이 가능한지를 파악하기 위한 것이다. 연구결과, 박판 모르타르 속에 배근된 섬유로빙이 인장보강재료로서 충분한 역할을 하며, 기본적인 휨이론을 바탕으로 이론식과 실험식을 비교한 결과, 두 값이 비교적 잘 일치하는 것으로 나타났다.
비접촉 겹침 이음된 프리캐스트 U형 보의 휨성능에 미치는 효과
하상수,김승훈 한국구조물진단유지관리공학회 2008 한국구조물진단유지관리공학회 논문집 Vol.12 No.6
본 연구는 중진지역에서의 PC(precast conctete) 보-기둥 접합부의 새로운 모멘트-저항 시스템을 제안하는 것이다. 철근 이음형 접합부에서 연결재는 접합부를 관통하고, U형 하프 PC 보의 하부철근과 비접촉 겹칩이음으로 연결되어 있다. 비접촉 겹침이음에 대한 성능을 파악하기 위하여 실험적 연구와 해석적 연구가 수행되었다. 실험의 주요변수는 겹침길이, 연결재의 크기, 그리고 겹침이음된 연결재의 거리 등이다. 또한, 균열양상, 하중-변위 곡선, 내력 비교, 그리고 연결재의 변형 등에 초점을 맞추어 해석적 연구를 수행하여 실험결과와 비교하였다. 해석과 실험 결과 주요변수인 겹침길이, 연결재의 크기, 연결재의 비접촉 수직 거리등에 따라 강도, 연성, 그리고 접합부 거동에 큰 영향을 주는 것으로 나타났다. In this study, new moment-resisting precast concrete beam-column joint is proposed for moderate seismic regions. It has the connection reinforcing bars, penetrated the joint and lap-spliced with the bottom bars of precast U-shaped PC beam. To evaluate the performance for noncontact lapped splice, experimental and analytical works were conducted. Major variables for tests are the length of lap, the diameter of connection reinforcing bars, and the distance between lapped bars. Analytic research was performed nonlinear finite element method. Analytic research focused on crack pattern, load-deflection curve, comparison of internal force, evaluation of ductility strains of reinforcement bar. Results of experimental and analytical works show that the these variables has much influence on flexural strength and ductility, and joint behavior.
하상수,Ha, Sang-Su 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 논문집 Vol.21 No.5
Although the strength of polyethylene terephthalate (PET) fibers which are generally used to make plastic bottles is low, the deformability of PET fibers is substantially high. Due to these material characteristics, a PET fiber can be used as a reliable strengthening material to resist a large deformation caused by earthquake and research pertinent to application of PET fibers is actively conducted in Japan. Therefore, in this study, experiments have been carried out to investigate the lateral confinement effect of PET fibers and to assess the applicability of PET fibers to construction fields by comparing the strengthening effect of PET fibers to that of carbon and glass fiber sheets. For this purpose, concrete cylinder specimens with parameters of different concrete strength and strengthening layers of carbon fiber sheets, glass fiber sheets, and PET fibers were respectively tested using two sets of cylinders for each parameter. As a result, specimens strengthened with carbon fiber sheets and glass fiber sheets failed due to sudden decrease of strength as with existing studies. However, specimens with PET fibers reached their maximum strength and then failed after gradual decrease strength without failure of PET fibers. In addition, although the strength of specimens with PET fibers did not significantly increase in comparison with that of specimens with carbon fiber sheets and glass fiber sheets, specimens with PET fibers indicated considerable deformability. Thus, a PET fiber can be considered as an effective strengthening material. 비닐용기 등에 주로 사용되는 PET 섬유는 강도는 아주 작은 반면, 변형성능에는 아주 우수하기 때문에 지진 발생시 구조물의 대변형에 효과적으로 저항할 수 있는 보강재료로 사용가능하며, 일본에서는 이미 PET 섬유를 이용한 연구를 진행하고 있는 실정이다. 따라서 본 연구에서는 PET(polyethylene terephthalate) 섬유의 횡구속 효과를 파악하고, PET 섬유의 보강효과와 기존에 사용해왔던 탄소섬유시트 및 유리섬유시트의 보강효과를 비교함으로써 PET 섬유의 현장적용성 여부를 파악하기 위한 것이다. 이를 위해 무근 콘크리트 공시체에 탄소섬유시트와 유리섬유시트 및 PET 섬유 등으로 구분하고 각각에 대해 콘크리트 강도와 보강겹수를 달리하여 실험체 별로 각각 2개씩 동일하게 제작하여 실험을 실시하였다. 실험결과, 탄소섬유시트 및 유리섬유시트로 보강된 실험체는 기존연구결과들과 마찬가지로 시트가 파단된 후 급격한 내력저하로 최종파괴 되었다. 그러나 PET로 보강한 실험체들은 PET 섬유가 파단되지 않고 최대 강도 이후 급격한 내력저하 없이 서서히 감소되면서 최종파괴 되었다. 또한, 탄소섬유시트 및 유리섬유시트로 보강한 실험체에 비해 강도증진 효과는 크지 않았으나, 연성측면에서는 매우 우수하게 나타나 향후 보강재료로 사용할 수 있을 것으로 판단된다.
신축이음장치의 앵커 인발성능 평가 및 나사 풀림 방지를 위한 앵커시스템 개발
하상수 한국건축시공학회 2010 한국건축시공학회지 Vol.10 No.1
The failure of expansion joints for bridges generally occurs in non-shrinkage mortar another problem is the release of anchors in expansion joints due to the impact and vibration that occurs when cars are driving over a bridge. In this study, to overcome the failure of expansion joints that is related to the failure of non-shrinkage mortar, an elastomeric mortar has been developed. The elastomeric mortar has a highly developed pull-out capacity compared with that of non-shrinkage mortar. Moreover, an anchor system that can be changed easily and prevent the fracture of expansion joints has been developed. 교량 신축이음장치의 파손 유형은 주로 후타재(무수축 모르타르)와 관련된 부분에서 많이 발생된다. 또 다른 문제는 중차량통과에 따른 충격과 진동하중으로 인해서 신축이음장치를 후타재에 고정하기 위해서 사용하는 앵커 풀림 현상이다. 본 연구에서는 무수축 모르타르의 파괴에 따른 신축이음장치의 파손을 방지하기 위해 탄성콘크리트를 개발하였다. 개발된 탄성콘크리트와 현재 주로 사용하고 있는 무수축 모르타르의 인발성능을 비교하였다. 또한, 후타재와 신축이음장치를 일체화하여 후타재의파손을 방지하고 신축이음장치를 쉽게 교체할 수 있는 앵커 시스템을 개발하였다.
하상수,윤정원,고민관,김대곤,김성진,홍태환,정승부,하상옥,김종웅 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4
This study investigated the microstructural evolution and evaluated the thermo-mechanical reliability of a Sn-3.0Ag-0.5Cu (in wt.%) flip chip package during a thermal shock test. The reliability of the flip chip bonded packages was evaluated by means of the thermal shock in the temperature range of 233 K to 398 K. After 250 thermal shock cycles, cracks finally occurred at the corner solder bump joint on the chip side interfacial regions. In that, the crack initiated at the solder region near the intermetallic compound (IMC) layers. For the interpretation of the failure mechanism of the package, finite element analyses were conducted. From the finite element analysis or computational simulation result, the distribution of the plastic work in the corner solder bump was found to be most considerable. This means that the corner solder bump has the highest potential for first crack initiation and growth, because the thermo-mechanical failure of the solder joints is mainly caused by the accumulation of the plastic work. This matched well with the experimental results. This study investigated the microstructural evolution and evaluated the thermo-mechanical reliability of a Sn-3.0Ag-0.5Cu (in wt.%) flip chip package during a thermal shock test. The reliability of the flip chip bonded packages was evaluated by means of the thermal shock in the temperature range of 233 K to 398 K. After 250 thermal shock cycles, cracks finally occurred at the corner solder bump joint on the chip side interfacial regions. In that, the crack initiated at the solder region near the intermetallic compound (IMC) layers. For the interpretation of the failure mechanism of the package, finite element analyses were conducted. From the finite element analysis or computational simulation result, the distribution of the plastic work in the corner solder bump was found to be most considerable. This means that the corner solder bump has the highest potential for first crack initiation and growth, because the thermo-mechanical failure of the solder joints is mainly caused by the accumulation of the plastic work. This matched well with the experimental results.
무연 솔더가 적용된 자동차 전장부품 접합부의 열적.기계적 신뢰성 평가
하상수,김종웅,채종혁,문원철,홍태환,유충식,문정훈,정승부,Ha, Sang-Su,Kim, Jong-Woong,Chae, Jong-Hyuck,Moon, Won-Chul,Hong, Tae-Hwan,Yoo, Choong-Sik,Moon, Jeong-Hoon,Jung, Seung-Boo 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.6
This study was focused on the evaluation of the thermo-mechanical board-level reliability of Pb-bearing and Pb-free surface mount assemblies. The composition of Pb-bearing solder was a typical Sn-37Pb and that of Pb-free solder used in this study was a representative Sn-3.0Ag-0.5Cu in mass %. Thermal shock test was chosen for the reliability evaluation of the solder joints. Typical $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed between both solders and Cu lead frame at the as-reflowed state, while a layer of $Cu_3Sn$ was additionally formed between the $Cu_6Sn_5$ and Cu lead frame during the thermal shock testing. Thickness of the IMC layers increased with increasing thermal shock cycles, and this is very similar result with that of isothermal aging study of solder joints. Shear test of the multi layer ceramic capacitor(MLCC) joints was also performed to investigate the degradation of mechanical bonding strength of solder joints during the thermal shock testing. Failure mode of the joints after shear testing revealed that the degradation was mainly due to the excessive growth of the IMC layers during the thermal shock testing.