• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.275-285
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• 2003

Pinching is an important property of reinforced concrete member which characterizes its cyclic behavior. In the present study, numerical studies were performed to investigate the characteristics and mechanisms of pinching behavior and the energy dissipation capacity of flexure-dominated reinforced concrete members. By analyzing existing experimental studies and numerical results, it was found that energy dissipation capacity of a member is directly related to energy dissipated by re-bars rather than concrete that is a brittle material, and that it is not related to magnitude of axial compressive force applied to the member. Therefore, for a member with specific arrangement and amount of re-bars, the energy dissipation capacity remains uniform regardless of the flexural strength that is changed by the magnitude of axial force applied. Due to the uniformness of energy dissipation capacity pinching appears in axial compression member. The flexural pinching that is not related to shear force becomes conspicuous as the flexural strength increases relatively to the uniform energy dissipation capacity. Based on the findings, a practical method for estimating energy dissipation capacity and damping modification factor was developed and verified with existing experiments.

• 한국지진공학회논문집
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• 제7권6호
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• pp.109-117
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• 2003

기존의 비선형 정적 및 동적 해석에서는 철근콘크리트 구조물의 에너지 소산능력을 정확히 고려하지 못하고 있다. 최근 연구에서는 휨지배 철근콘크리트 부재의 에너지 소산능력을 정확히 평가할 수 있는 식이 개발되었으며, 본 연구에서는 이 평가방법을 이용하여 에너지 소산능력을 정확히 고려할 수 있는 비선형 정적 및 동적 해석 방법을 개발하였다. 비선형 정적 해석을 위하여 에너지 스펙트럼 곡선을 개발하고 이를 적용하여 능력스펙트럼법을 개선하였으며, 또한 비선형 동적 해석을 위하여 철근콘크리트 부재의 단순화된 에너지 기초 주기거동모델을 개발하였다. 제안된 모델은 부재의 강성에 기초한 기존의 주기거동모델과는 달리 완전한 주기거동 발생시 소산되는 에너지를 정확하게 반영할 수 있다. 본 연구에서는 제안된 방법에 따라 비선형 정적 및 동적 해석법의 절차를 정립하였으며 이를 적용한 컴퓨터 해석 프로그램을 개발하였다. 제안된 해석 방법은 부재의 단면형태, 철근비, 배근형태 등 설계 변수에 따른 에너지 소산능력을 정확하게 고려하고 지진발생시 에너지 소산능력이 구조물의 성능에 미치는 효과를 반영할 수 있다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.172-179
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• 2003

In the performance based seismic design method such as the capacity spectrum method, it is required to estimate precisely strength, deformability and energy dissipation of the member. However it merely depends on empirical equations which are not exact in the estimation of energy dissipation capacity. It is same to the generously used computer programs for nonlinear analysis such as DRAIN-2DX. On the other hand, simple equations for evaluating energy dissipation were developed in a recent study, In this paper, based on the evaluation method, a new cyclic behavior model for a flexure-dominated RC member is proposed. Although this model is simplified, it can accurately reflect the variation of energy dissipation capacity with design parameters. Using this model, a program for the nonlinear static/dynamic analysis of RC moment frame structures is also developed.

• Computers and Concrete
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• 제30권5호
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• pp.311-321
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• 2022

The interfacial bond strength of partially encased composite (PEC) structure tends to 0, therefore, the cast-in-place concrete theoretically cannot embody better composite effect than the fabricated structure. A total of 12 specimens were designed and experimented to investigate the energy dissipation and damage of fabricated PEC beam through unidirectional cyclic loading test. Because the concrete on both sides of the web was relatively independent, some specimens showed obvious asymmetric concrete damage, which led to specimens bearing torsion effect at the later stage of loading. Based on the concept of the ideal elastoplastic model of uniaxial tensile steel and the principle of equivalent energy dissipation, the energy dissipation ductility coefficient is proposed, which can simultaneously reflect the deformability and bearing capacity. In view of the whole deformation of the beam, the calculation formula of energy dissipation is put forward, and the energy dissipation and its proportion of shear-bending region and pure bending region are calculated respectively. The energy dissipation efficiency of the pure bending region is significantly higher than that of the shear-bending region. The setting of the screw arbors is conducive to improving the energy dissipation capacity of the specimens. Under the condition of setting the screw arbors and meeting the reasonable shear span ratio, reducing the concrete pouring thickness can lighten the deadweight of the component and improve the comprehensive benefit, and will not have an adverse impact on the energy dissipation capacity of the beam. A damage model is proposed to quantify the damage changes of PEC beams under cyclic load, which can accurately reflect the load damage and deformation damage.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.85-88
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• 2004

In this study, a simple moment-resisting precast concrete beam-column connection is proposed for highly seismic zone using dywidag ductile rod [DDC]. DDC is superior system for ductility, energy dissipation capacity, connection strength, and drift capacity. A study was carried out to investigate the connection behavior subjected to cyclic inelastic loading. Four Precast beam-column interior connections and one monolithic connection will be tested. The variables will be examined were the strength relationship between joint's ductile rod and beam reinforcement for gain energy dissipation capacity. The specimens will be tested only reverse cyclic loading in accordance with a prescribed displacement history. Connection performance is evaluated on the basis of ductility, energy dissipation capacity, connection strength, and drift capacity. the precast connection using DDC is capable of matching of exceeding the performance of the monolithic connection and thereby provides moment-resisting behavior.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.247-257
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• 2002

Recently, performance-based analysis/design methods such as the capacity spectrum method and the direct displacement-based design method were developed. In these methods, the estimation of energy dissipation capacity due to inelastic behavior of RC structures depends on empirical equations which are not sufficiently accurate. On the other hand, in a recent study, a simplified method for evaluating energy dissipation capacity was developed. In the present study, based on the evaluation method, a new seismic design method for flexure-dominated RC walls is developed. In determination of seismic earthquake load, the proposed design method can address variation of the energy dissipation capacity with design parameters such as dimensions and shapes of cross-sections, axial force, and reinforcement ratio and arrangement. The proposed design method is compared with the current performance-based design methods and the applicability of the proposed method is disscussed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.297-305
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• 2002

As advanced earthquake analysis/design methods such as the nonlinear static analysis are developed, it is required to estimate precisely the cyclic behavior of reinforced concrete members that is characterized by strength, deformability, and capacity of energy dissipation. However, currently, estimation of energy dissipation depends on empirical equations that are not sufficiently accurate, or experiment and sophisticated numerical analysis which are difficult to use in practice. In the present study, nonlinear finite element analysis was performed to investigate the behavioral characteristics of flexure-dominant RC members under cyclic load. The effects of axial force, arrangement of reinforcing bars, and reinforcement ratio on the cyclic behavior were studied. Based on the investigation, a simplified method to estimate the capacity of energy dissipation was proposed, and it was verified by the comparison with the finite element analyses and experiments. The proposed method can estimate the energy dissipation of RC members more precisely than currently used empirical equations, and it is easily applicable in practice.

• Steel and Composite Structures
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• 제43권1호
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• pp.55-66
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• 2022

To develop high-efficiency lateral force resistance components for high-rise buildings, a novel energy dissipation shear wall with concrete-filled steel tubular (CFST) column elements was proposed. An energy dissipation shear wall specimen with CFST column elements (GZSW) and an ordinary reinforced concrete shear wall (SW) were constructed, and experimented by low-cycle reversed loading. The mechanical characteristics of these two specimens, including the bearing capacity, ductility, energy dissipation, and stiffness degradation process, were analyzed. The finite-element model of the GZSW was established by ABAQUS. Based on this finite-element model, the effect of the placement of steel-plate energy dissipation connectors on the seismic performance of the shear wall was analyzed, and optimization was performed. The experiment results prove that, the GZSW exhibited a superior seismic performance in terms of bearing capacity, ductility, energy dissipation, and stiffness degradation, in comparison with the SW. The results calculated by the ABAQUS finite-elements model of GZSW corresponded well with the results of experiment, and it proved the rationality of the established finite-elements model. In addition, the optimal placement of the steel-plate energy dissipation connectors was obtained by ABAQUS.

• 콘크리트학회논문집
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• 제15권4호
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• pp.594-605
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• 2003

핀칭은 철근콘크리트 부재의 주기거동 특성을 나타내는 중요한 요소이다. 본 연구에서는 휨지배를 받는 철근콘크리트 부재에 대하여 핀칭거동의 특성과 에너지 소산능력을 연구하기 위하여 수치해석 연구를 실시하였다. 기존의 실험연구와 수치해석 결과를 분석한 결과, 전단거동과 무관한 휨핀칭이 압축력을 받는 부재에서 일어난다는 사실이 밝혀졌다. 그러나 일정한 철근 배근형태와 철근양을 갖는 부재들은 압축력의 영향에 의하여 주기거동의 형상이 변하더라도 재하된 압축력의 크기와 관계없이 일정한 에너지소산능력을 갖는다. 이는 콘크리트는 압축력이 증가함에 따라서 그 영향력이 증대되지만 취성재료로서 에너지 소산능력에 큰 영향을 미치지 않으며, 주로 철근에 의하여 에너지 소산이 일어난다는 사실을 가리킨다. 따라서 실제 재하되는 압축력의 크기에 관계없이 단순 휨을 받는 단면에 대한 해석을 통하여 휨지배 부재의 에너지 소산능력을 계산할 수 있다. 이러한 연구결과에 근거하여 에너지 소산능력과 감쇠보정계수를 평가할 수 있는 실용적인 방법과 설계식을 개발하였으며, 기존의 실험결과와의 비교를 통해 검증하였다. 이 제안된 방법은 일반적인 설계변수를 이용하여 에너지소산능력을 정확히 평가할 수 있으므로, 설계실무에서 편리하게 사용할 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.9-12
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• 2004

Coupling beams subject to cyclic loads exhibit different behavioral characteristics and energy dissipation capacity varying with re-bar layouts. In the present study, nonlinear analysis method was developed using analogous truss model. Using the numerical method, parametric studies were performed to investigate the behavioral characteristics and the energy dissipation mechanism of coupling beams with various re-bar layouts subject to cyclic loading. Based on the investigation, a simple and practical method for evaluating the energy dissipation capacity of coupling beams was developed and verified by experiments. The proposed method accurately predicted the dissipated energy during cyclic loading addressing design parameters such as re-bar layouts, re-bar ratio, and deformation. The proposed method can be easily applied to nonlinear static and dynamic methods for seismic analysis and design.