• Structural Engineering and Mechanics
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• 제85권5호
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• pp.655-664
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• 2023

Reinforced concrete (RC) shear wall structures are one of the most widely used structural systems to resist seismic loading all around the world. Although there have been several efforts to provide conceptually simple procedures to reasonably assess the seismic demands of structures over recent decades, it seems that lesser effort has been put on a number of structural forms such as RC shear wall structures. Therefore, this study aims to represent a simple linear response spectrum-based method which can acceptably predict the nonlinear displacements of a non-ductile RC shear wall structure subjected to an individual ground motion record. An effective period and an equivalent damping ratio are introduced as the dynamic characteristics of an equivalent linear SDOF system relevant to the main structure. By applying the fundamental mode participation factor of the original MDOF structure to the linear spectral response of the equivalent SDOF system, an acceptable estimation of the nonlinear displacement response is obtained. Subsequently, the accuracy of the proposed method is evaluated by comparison with another approximate method which is based on linear response spectrum. Results show that the proposed method has better estimations for maximum nonlinear responses and is more utilizable and applicable than the other one.

• Structural Engineering and Mechanics
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• 제23권4호
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• pp.369-386
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• 2006

The influence of reinforcement buckling on the flexural response of reinforced concrete members is studied. The stress-strain response of compression reinforcement is determined computationally using a large-strain finite element model for bars of varied diameter, length, and initial eccentricity, and a mathematical expression is fitted to the simulation results. This relationship is used to represent the response of bars in compression in a moment-curvature analysis of a reinforced concrete cross section. The compression bar may carry more or less force than a tension bar at a corresponding strain, depending on the relative influence of Poisson effects and bar slenderness. Several cross-section analyses indicate that, for the distances between stirrups prescribed in modern concrete codes, the influence of inelastic buckling of the longitudinal reinforcement on the monotonic moment capacity is very small and can be neglected in many circumstances.

• Structural Engineering and Mechanics
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• 제86권2호
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• pp.277-290
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• 2023

A supplementary reinforced concrete wall can be used to improve the seismic behavior of a buckling restrained braced frame as a mixed system. In such a novel system, the total lateral force is resisted by the combination of the RC wall system and the BRBF. There is not enough research on the response modification factor of such a mixed system. This paper investigates the response modification factor, and such relevant factors as ductility reduction factor and over strength factor for a system consisting of reinforced concrete wall and buckling restrained braced frame. To this purpose, nonlinear incremental dynamic analysis as well as static push over analysis are used for 6- to 14-story sample structures. The results show that for mixed considered systems, the mean value of response modification factor varies approximately from 7 to 9.

• 한국구조물진단유지관리공학회 논문집
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• 제24권5호
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• pp.135-142
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• 2020

구조물을 구성하고 있는 콘크리트의 경우, 진동에 대한 감쇠성능이 작아, 구조물에서 발생하는 다양한 진동 문제를 해결하는데 어려움이 있으므로, 이러한 문제를 해결하기 위해, 최근 폴리머 콘크리트와 복합구조 댐퍼를 혼합하여 댐핑 성능을 크게 증가시킨 고 감쇠 시스템에 대한 연구가 활발히 진행되고 있다. 한편, 폴리머 콘크리트는 배합 시, 시멘트와 물을 사용하지 않아, 경화시간이 매우 짧고, 물리적 특성 및 동특성 등이 매우 우수하여 진동저감이 요구되는 건축구조물에의 폭넓은 활용이 기대되는 구조재료이며, 복합구조 댐퍼는 파이프 관 내부에 위치한 쇠구슬의 충돌에 따른 운동에너지 소산과 점성유체의 에너지 소산 방식을 통해 진동을 저감하는 구조시스템이라 할 수 있다. 본 연구에서는 폴리머 콘크리트와 복합구조 댐퍼의 물리적, 동적 특성을 일반 콘크리트와 비교하였는데, 물리적 특성의 경우, 폴리머 콘크리트가 탄성계수 및 강도 특성에서 상당히 우수한 결과를 보였으며, 특히 인장강도는 6.5~10배 이상 큰 차이를 보였다. 또한, 동적 특성의 경우도 폴리머 콘크리트는 일반 콘크리트 대비 동적강성은 25%, 감쇠비는 약 3배 정도 증가하였으며, 복합구조 댐퍼는 동적강성은 비슷한 경향을 보였지만 감쇠비는 3.5배 이상 증가하여, 일반 콘크리트보다 진동 감쇠성능이 우수한 것으로 나타났다.

• 한국지진공학회논문집
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• 제5권6호
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• pp.11-19
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• 2001

일정한 축하중과 반복적인 횡하중을 받는 콘크리트충전 강합성 기둥의 내진성능에 관한 실험적인 연구가 수행되었다. 강합성 기둥은 충전콘크리트가 강판의 국부좌굴로 인한 내측방향의 변형을 억제하고, 강판의 콘크리트 측압에 대한 구속효과와 같은 상호작용에 의해서 콘크리트와 강재의 단순누가강도 이상의 강도증진효과를 가지며, 강재 및 콘크리트기둥에 비해 우수한 연성 및 에너지 흡수능력을 나타내었다. 단면분할법을 이용하여 콘크리트충전 강합성 기둥의 비선형 모멘트-곡률 관계를 예측해 보았으며, 이는 실험결과와 비교적 잘 일치하는 것으로 나타났다. 또한, 구조물의 내진설계의 중요한 요소인 강합성 기둥의 연성 및 응답수정계수를 평가해 보았다. 실험결과 강합성 기둥은 효과적인 내진구조 부재로 판단되었다.

• 콘크리트학회논문집
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• 제11권6호
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• pp.101-112
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• 1999

Structural walls have been mostly used for the design of reinforced concrete buildings in seismic areas because they play a role as an efficient bracing system and offer great potential for lateral load resistance and drift control. The lateral resistance system for the earthquake load should be designed to have enough ductility and stable hysteretic response in the critical regions where plastic deformation occurred beyond yielding. The behavior of the reinforced concrete element to experience large deformation in the critical areas by a major earthquake is affected by the performance of the confined core concrete. Thus, the confinement of concrete by suitable arrangements of transverse reinforcement results in a significant increase in both the strength and ductility of compressed concrete. This paper reports the experimental results of reinforced concrete structural walls for wall-type apartment structure under axial loads and cyclic reversal of lateral loads with different confinement of the boundary elements. The results show that confinement of the boundary element by open 'U'-bar and cross tie is effective. The shear strength capacity is not increased by the confinement but deformation capacity is improve.

• Computers and Concrete
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• 제15권2호
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• pp.215-229
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• 2015

The emerging technology of self compacting concrete, fiber reinforcement together reduces vibration and substitute conventional reinforcement which help in improving the economic efficiency of the construction. The objective of this work is to find the regression model to determine the response surface of mix proportioning Steel Fiber Reinforced Self Compacting Concrete (SFSCC) using statistical investigation. A total of 30 mixtures were designed and analyzed based on Design of Experiment (DOE). The fresh properties of SCC and mechanical properties of concrete were studied using Response Surface Methodology (RSM). The results were analyzed by limited proportion of fly ash, fiber, volume combination ratio of two steel fibers with aspect ratio of 50/35: 60/30 and super plasticizer (SP) dosage. The center composite designs (CCD) have selected to produce the response in quadratic equation. The model responses included in the primary stage were flowing ability, filling ability, passing ability and segregation index whereas in harden stage of concrete, compressive strength, split tensile strength and flexural strength at 28 days were tested. In this paper, the regression model and the response surface plots have been discussed, and optimal results were found for all the responses.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.412-415
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• 2004

This study was performed to verify the behaviors of fiber Bragg grating (FBG) sensors attached to the containment structure in the nuclear power plant as a part of structural integrity test which demonstrates that the structural response of the non-prototype primary containment structure is within predicted limits plus tolerances when pressurized to $115\%$ of containment design pressure, and that the containment does not sustain any structural damage.

• International Journal of Concrete Structures and Materials
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• 제5권1호
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• pp.19-28
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• 2011

This paper documents an experimental study of dynamic response of reinforced concrete beams following instantaneous removal of a bearing column. Four half-scale specimens representing two-span beam bridging across the removed column were tested. The test boundary conditions simulated rotational and longitudinal restraints imposed on a frame beam by the neighboring structural components. The gravity loads were simulated by attaching mass blocks on the beams at three locations. Dynamic loading effects due to sudden removal of a column were simulated by quickly releasing the supporting force at the middle of the specimens. The experimental study investigated the load-carrying capacity of beams restrained longitudinally at the boundaries and dynamic impact on forces. The tests confirmed the extra flexural strength provided by compressive arch action under dynamic loading. The tests also indicated that the dynamic amplification effects on forces were much lower than that assumed in the current design guideline for progressive collapse.

• Steel and Composite Structures
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• 제39권2호
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• pp.135-148
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• 2021

Hollow structural section (HSS) columns have been increasingly popular due to their structural and architectural merits. However, practical difficulty lies in developing proper connections. The through-diaphragm connections are considered as suitable connection type that is widely adopted in Asian countries. However, the stress concentration occurs at the location connecting through-diaphragm and steel beam. Furthermore, the actual load path from the beam flange is not uniformly transferred to the HSS column as conventionally assumed. In this paper, tensile tests were further conducted on three additional specimens with beam flange plate to evaluate the load versus displacement response. The load-displacement curves, yield and ultimate capacity, ductility ratio were obtained. Furthermore, the strain development at different loading levels was discussed comprehensively. It is shown that the studied connection configuration significantly reduces the stress concentration. Meanwhile, simplified trilinear load-displacement analytical model for specimen under tensile load was presented. Good agreement was found between the theoretical and experimental results.