• 한국공간구조학회논문집
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• 제23권1호
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• pp.61-68
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• 2023

Buckling Restrained Braces can not only express the strength considered at the time of design, but also reduce the seismic load by energy dissipation according to the plastic behavior after yield deformation of the steel core. The physical characteristics and damping effect may be different according to the buckling prevention method of the steel core by the lateral restraint element. Accordingly, in this study, To compare hysteresis characteristics, Specimen(BRB-C) filled with mortar, specimen(BRB-R) combined with a buckling restraint ring and Specimen(BRB-EP) filled with engineering plastics was fabricated, and a cyclic loading test was performed. As a result of the cyclic loading test, the maximum compressive strength, cumulative energy dissipation and ductility of each test specimen was similar. But in case of the cumulative energy dissipation and ductility, BRB-C filled with the mortar specimen showed the lowest. This is considered to be because the gap between the steel core and the reinforcing material for plastic deformation was not uniformly formed by pouring mortar around the core part.

• 한국지진공학회논문집
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• 제17권2호
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• pp.79-88
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• 2013

Steel plate concrete (SC) composite structure is now being recognized as a promising technology applicable to nuclear power plants as it is faster and suitable for modular construction. It is required to identify its dynamic characteristics prior to perform the seismic design of the SC structure. Particularly, the damping ratio of the structure is one of the critical design factors to control the dynamic response of structure. This paper compares the criteria for the damping ratios of each type of structures which are prescribed in the regulatory guide for the nuclear power plant. In order to identify the damping ratio of SC shear wall, this study made SC wall specimens and conducted experiments by cyclic lateral load tests and vibration tests with impact hammer. During the lateral loading test, SC wall specimens exhibited large ductile capacities with increasing amplitude of loading due to the confinement effects by the steel plate and the damping ratios increased until failure. The experimental results show that the damping ratios increased from about 6% to about 20% by increasing the load from the safe shutdown earthquake level to the ultimate strength level.

• Earthquakes and Structures
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• 제19권1호
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• pp.29-44
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• 2020

The effectiveness and the sensitivity of a Wireless impedance/Admittance Monitoring System (WiAMS) for the prompt damage diagnosis of two single-storey single-span Reinforced Concrete (RC) frames under cyclic loading is experimentally investigated. The geometrical and the reinforcement characteristics of the RC structural members of the frames represent typical old RC frame structure without consideration of seismic design criteria. The columns of the frames are vulnerable to shear failure under lateral load due to their low height-to-depth ratio and insufficient transverse reinforcement. The proposed Structural Health Monitoring (SHM) system comprises of specially manufactured autonomous portable devices that acquire the in-situ voltage frequency responses of a network of twenty piezoelectric transducers mounted to the RC frames. Measurements of external and internal small-sized piezoelectric patches are utilized for damage localization and assessment at various and increased damage levels as the magnitude of the imposed lateral cycle deformations increases. A bare RC frame and a strengthened one using a pair of steel crossed tension-ties (X-bracing) have been tested in order to check the sensitivity of the developed WiAMS in different structural conditions since crack propagation, damage locations and failure mode of the examined frames vary. Indeed, the imposed loading caused brittle shear failure to the column of the bare frame and the formation of plastic hinges at the beam ends of the X-braced frame. Test results highlighted the ability of the proposed SHM to identify incipient damages due to concrete cracking and steel yielding since promising early indication of the forthcoming critical failures before any visible sign has been obtained.

• 콘크리트학회논문집
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• 제28권2호
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• pp.129-139
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• 2016

대형 PC기둥의 양중부하를 줄이고 접합부의 구조일체성을 개선하기 위한 대안으로서, 중공 PC기둥이 사용될 수 있다. 본 연구에서는 PC부의 생산성과 구조일체성을 개선한 새로운 중공 PC기둥을 개발하였다. PC부를 제작하기 위하여 구조용 골형플레이트를 내부영구거푸집과 수평 관통철근을 사용하였다. 제안된 PC기둥의 내진성능을 검증하기 위하여, 1/2 스케일의 기둥 실험체 4개에 대하여 일정 축력에서 반복 횡가력실험을 수행하였다. 실험 변수로는 횡철근 간격, 강섬유 사용여부, 그리고 PC부의 두께가 고려되었다. 실험 결과, 제안된 PC기둥은 외곽 PC부의 취성적인 파괴 없이 우수한 하중재하능력과 변형능력을 보이는 것으로 나타났다. PC부에 횡철근을 촘촘히 배근하거나 강섬유를 사용할 경우, PC 콘크리트의 탈락을 제한하여 변형능력을 증가시킬 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.77-80
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• 2006

Longitudinal reinforcements of the plastic hinge region were behaved tensile deformation and compressional deformation by direction of lateral loading. However Confinement steels were behaved only tensile deformation by lateral loading. Transverse steels were laid the state of tension in the lateral loading of time, and they were laid state that stress is zero when it was removed lateral load. Nine specimens were tested under cyclic stresses(tension and zero). The purpose of this research is to investigate the strain behavior and capacity of energy for confinement steel. The selected test variables are $L/d_b(L/d_b=6)$, size of reinforcement and specified yielding strength(300, 400, 500 MPa).

• 한국구조물진단유지관리공학회 논문집
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• 제11권3호
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• pp.143-150
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• 2007

본 연구에서는 카본시트튜브로 구속된 원형기둥에 반복 횡하중을 가하여 기둥의 휨내력을 평가하는 실험을 수행하였다. 중립축을 기준으로 압축 및 인장측 단면의 모멘트를 이용하여 공칭모멘트를 계산하는 등가응력블록계산법을 소개하였다. 또한 실험결과를 분석하여 횡 하중에 대한 거동을 예측할 수 있는 회귀식을 마련하여 실험결과와 비교하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.232-239
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• 2005

Recently geosynthetics that can be constructed on soft ground have been used for reinforcement and separation in various ways. Through laboratory model tests and numerical analysis, in this study, estimated the suitability of cable elements and appropriate input factors considering loading effect in modeling of geosynthetics. First, in laboratory model tests, geosynthetics were constructed on the clay, and covered with the thickness, 7.5cm of sand mat. And then static and dynamic model tests were performed measuring loading, settlement, ground lateral displacement, and displacements of geosynthetics, but, for cyclic loading, bearing capacity increased linearly with stiff slop because cyclic loading with constant cyclic pressure compacted the ground. Numerical analysis were performed with FLAC 4.0 2D using Mohr-Coulomb and Modified Cam-Clay models, and they compared with the results of model tests. Cable elements of FLAC in modeling geosynthetics couldn't consider the characteristics of geosynthetics that increase shear strength between geosynthetics and clay according to the loading increase. Therefore, in this study, appropriate equation that can consider loading effects in Cable elements was proposed by Case Study.

• 한국공간구조학회논문집
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• 제15권4호
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• pp.73-80
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• 2015

The new rotary friction damper was developed using several two-nodal rotary frictional components with different clamping forces. Because of these components, the rotary friction damper can be activated by building movements due to lateral forces such as a wind and earthquake. In this paper, various dependency tests such as displacement amplitude, forcing frequency and long term cyclic loading were carried out to evaluate on the structural performance and the multi-slip mechanism of the new damper. Test results show that the multi-slip mechanism is verified and friction coefficients are dependent on displacement amplitute and forcing frequency except long term cyclic loading.

• Structural Engineering and Mechanics
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• 제17권1호
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• pp.69-85
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• 2004

The novel form of composite walling system consists of two skins of profiled steel sheeting with an in-fill of concrete. Such walling system can be used as shear elements in steel framed building subjected to lateral load. This paper presents the results of small-scale model tests on composite wall and its components manufactured from very thin sheeting and micro-concrete tested under monotonic and cyclic shear loading conditions. The heavily instrumented small-scale tests provided information on the load-deformation response, strength, stiffness, strain condition, sheet-concrete interaction and failure modes. Analytical models for shear strength and stiffness are derived with some modification factor to take into account the effect of quasi-static cycling loading. The performance of design equations is validated through experimental results.

• 한국구조물진단유지관리공학회 논문집
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• 제11권4호
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• pp.99-108
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• 2007

풍하중 및 지진하중등 횡하중이 작용하는 무량판 슬래브는 전단파괴와 같은 취성파괴를 지연시키기 위해서 충분한 전단강도와 연성능력을 보유하여야 한다. 본 연구에서는 반복 횡하중을 받는 무량판 슬래브의 전단강도와 변형성능을 고찰하기 위하여, 무보강 및 전단 보강된 총 4개의 내부기둥-슬래브 접합부를 실험하였다. 실험결과, 전단보강 슬래브의 이방향 전단강도는 무보강 슬래브보다 최대 1.5배까지 증가시켜 적용하는 콘크리트구조설계기준(KCI)과 ACI 318-02 기준은 중력하중만이 작용하는 경우에는 적절하나 조합하중 특히 횡하중의 영향이 클 경우에는 매우 불안전측 이었다. 한편, 변형성능 측면에서 슬래브-기둥 접합부의 1.5% 횡변위 성능을 확보하기 위하여 이방향 전단강도에 대한 중력하중비를 40%이하로 제한한 ACI-ASCE 352 위원회의 권고는 안전측인 것으로 나타났다.