• Steel and Composite Structures
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• 제20권1호
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• pp.57-70
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• 2016

The predominant type of buckling that I-steel concrete composite beams experience in the negative moment area is distortional buckling. The key factors that affect distortional buckling are the torsional and lateral restraints by the bottom flange. This study thoroughly investigates the equivalent lateral and torsional restraint stiffnesses of the bottom flange of an I-steel concrete composite beam under negative moments. The results show a coupling effect between the applied forces and the lateral and torsional restraint stiffnesses of the bottom flange. A formula is proposed to calculate the critical buckling stress of the I-steel concrete composite beams under negative moments by considering the lateral and torsional restraint stiffnesses of the bottom flange. The proposed method is shown to better predict the critical bending moment of the I-steel composite beams. This article introduces an improved method to calculate the elastic foundation beams, which takes into account the lateral and torsional restraint stiffnesses of the bottom flange and considers the coupling effect between them. The results show a close match in results from the calculation method proposed in this paper and the ANSYS finite element method, which validates the proposed calculation method. The proposed calculation method provides a theoretical basis for further research on distortional buckling and the ultimate resistance of I-steel concrete composite beams under a variable axial force.

• 대한기계학회논문집A
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• 제37권5호
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• pp.641-648
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• 2013

보 구조물들은 보다 우수한 성능을 위하여 다양한 형태의 보강재 또는 단면 형상을 가지게 된다. 강성재단을 설계에 적용하기 위해서는 강성재단에 의해서 발생하는 연계 거동을 정확하게 예측하는 것이 필요하다. 본 연구에서는 문헌에서 보고된 복합재료 보의 특이한 연계거동(면외 굽힘-전단 연계)을 실험적으로 확인하기 위하여, 등가의 동적 연계거동을 나타내는 강성재단 된 등방성 박스보를 제작하였다. 제작된 시편의 주파수 및 모드 형상 등의 동적 특성을 3 차원 유한요소해석과 비교 검토하여, 문헌에 보고된 특이한 전단 연계 거동이 발생함을 확인하였다. 이러한 거동은 보강재의 적절한 배치를 통해 원하는 방향으로 강성재단 될 수 있고, 얻어진 연계 거동은 다양한 분야에 응용될 수 있다.

• 한국지진공학회논문집
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• 제22권2호
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• pp.95-101
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• 2018

Diagonally reinforced concrete coupling beams (DRCB) play an important role in coupled shear wall systems since these elements dissipate most of seismic input energy under earthquake loading. For reliable seismic performance evaluation using nonlinear response history analysis, it is important to use an accurate analytical model for DRCBs. In this study, the Pinching4 model is used as a base model to simulate the cyclic behavior of DRCBs. For simulating the cyclic behavior of DRCBs using the Pinching4 model, the analytical parameters for backbone curve, pinching and cyclic deterioration in strength and stiffness should be computed. To determine the proper values of the constituent analytical parameters efficiently and accurately, this study proposes the empirical equations for the analytical parameters using regression analyses. It is shown that the hysteretic behavior of coupling beams can be simulated efficiently and accurately using the proposed numerical model with the proposed empirical equations of model parameters.

• Earthquakes and Structures
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• 제9권6호
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• pp.1251-1272
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• 2015

It is widely recognized that the preferred yielding mechanism for a hybrid coupled wall structure is that all coupling beams over the height of the structure yield in shear prior to formation of plastic hinges in structural walls. The objective of the study is to provide feasible approaches that are able to promote the preferred seismic performance of hybrid coupled walls. A new design methodology is suggested for this purpose. The coupling ratio, which represents the contribution of coupling beams to the resistance of system overturning moment, is employed as a fundamental design parameter. A series of nonlinear time history analyses on various representative hybrid coupled walls are carried out to examine the adequacy of the design methodology. While the proposed design method is shown to be able to facilitate the desired yielding mechanism in hybrid coupled walls, it is also able to reduce the adverse effects caused by the current design guidelines on the structural design and performance. Furthermore, the analysis results reveal that the state-of-the-art coupled wall design guidelines could produce a coupled wall structure failing to adequately exhaust the energy dissipation capacity of coupling beams before walls yield.

• 콘크리트학회논문집
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• 제17권6호
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• pp.1001-1009
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• 2005

고층 건물의 구조계획에서 벽체의 유용성은 오래전부터 인식되어 왔다. 구조물에서 적절한 위치에 벽체를 배치하며, 벽체는 구조물에 작용하는 횡하중에 매우 효과적으로 저항할 수 있다. 특히 병렬 전단벽 시스템의 구조물의 횡력저항 시스템으로서 가장 선호되는 구조이고 이러한 구조는 커플링보에 의해 벽체가 연결되게 된다. 커플링보는 강도, 강성, 연성 및 에너지 소산능력이 충분한 부재이어야 한다. 이러한 요구들을 만족시키기 위해 FBP를 적용한 철골 커플링보를 제안한다. FBP의 적용 여부를 변수로 하여 총 2개의 시험체를 계획하고 실험을 실시하였다. 이러한 실험 연구를 통하여 FBP를 적용한 철골 커플링보의 장점에 대해 서술하였고, 파괴모드를 제안하였다.

• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.181-190
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• 2019

In this study, four reinforced concrete coupling beams were subjected to cyclic lateral loading test to evaluate the structural performance of coupling beam according to volume fraction of steel fiber. For this purpose, the volume fraction of steel fiber(0%, 1%, 2%) and transverse reinforcement spacing were determined as the main parameter. According to the test results, the maximum strength of D-40C-s100-0 was 1.15, 1.13, 1.05 times higher than D-40C-s300-0, D-40C-s300-1, D-40C-s300-2, respectively. The maximum strength of coupling beams with mitigated rebar details increases as the volume fraction of steel fiber increases. Although steel fiber 2% reinforced specimen(D-40C-s300-2) did not satisfy the amount of transverse reinforcement required for seismic design of coupling beam, the overall performance including to maximum strength, ductility and energy dissipation capacity was similar to the control specimen(D-40C-s100-0). As a result, the use of steel fiber with 2% reinforcement can partially replace the transverse reinforcement in diagonally reinforced concrete coupling beam.

• 한국지진공학회논문집
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• 제14권6호
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• pp.1-9
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• 2010

대부분의 전단벽 구조물은 통로의 목적으로 개구부를 필요로 하게 되고 전단벽들 사이가 슬래브나 연결보로 연결된 병렬 전단벽의 형태를 띠게 된다. 이러한 구조물에 지진하중이 작용할 때 연결보에 과도한 전단력이 작용하여 연결보가 취성적으로 파괴되거나 전단벽이 먼저 항복하는 문제점이 발생할 수 있다. 이를 방지하기 위하여 연결보에 감쇠장치를 설치하게 되면 구조물의 진동제어효과와 더불어 연결보의 응력집중 및 취성적 파괴를 막을 수 있어서 내진성능 향상을 기대할 수 있다. 본 논문에서는 병렬전단벽 연결보 중앙부에 LRB (Lead Rubber Bearing)가 설치된 구조물의 지진응답제어효과 및 응력의 분포를 평가하여 구조적 효율성을 확인하고자 한다. 이를 위하여 병렬전단벽의 거동을 비교적 정확하게 모사할 수 있는 모형화 방법을 제안하였고, 제안된 모형화 방법을 통하여 지진하중을 받는 예제 병렬구조물에 대한 시간이력해석을 수행한 후 지진응답제어성능을 검토하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.257-260
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• 2006

Coupled shear walls consist of two or more in-plane walls inter-connected with coupling beams. In order to effectively resist seismic loads, coupling beams must be sufficiently stiff, strong and posses a stable load-deflection hysteretic response. Much of requirements to the civil and building structures have recently been changed in accordance with the social and economic progress. Ductility of high performance fiber reinforced cementitious composites(HPFRCCs), which exhibit strain hardening and multiple crackling characteristics under the uniaxial tensile stress is drastically improved. This paper provides background for design guidelines that include a design model to calculate the shear strength of pseudo strain hardening cementitious composite steel coupling beam.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.174-177
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• 2006

To restore an earthquake damaged community as quickly as possible, well-prepared reconstruction strategy is most essential. This paper reports experimental data on the seismic capacity of diagonal reinforced HPFRCC coupling beams with the Japanese Standard for Seismic Evaluation of Existing RC Buildings. Precast Based on the experimental results, HPFRCC specimen have more residual seismic capacity than RC specimen, but much study is necessary to improve the accuracy of the damage evaluation.

• Structural Engineering and Mechanics
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• 제36권5호
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• pp.545-560
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• 2010

Two or more distinct materials are combined into a single functionally graded material (FGM) where the microstructural composition and properties change gradually. Thermal post-buckling behavior of uniform slender FGM beams is investigated independently using the classical Rayleigh-Ritz (RR) formulation and the versatile Finite Element Analysis (FEA) formulation developed in this paper. The von-Karman strain-displacement relations are used to account for moderately large deflections of FGM beams. Bending-extension coupling arising due to heterogeneity of material through the thickness is included. Simply supported and clamped beams with axially immovable ends are considered in the present study. Post-buckling load versus deflection curves and buckled mode shapes obtained from both the RR and FEA formulations for different volume fraction exponents show an excellent agreement with the available literature results for simply supported ends. Response of the FGM beam with clamped ends is studied for the first time and the results from both the RR and FEA formulations show a very good agreement. Though the response of the FGM beam could have been studied more accurately by FEA formulation alone, the authors aim to apply the RR formulation is to find an approximate closed form post-buckling solutions for the FGM beams. Further, the use of the RR formulation clearly demonstrates the effect of bending-extension coupling on the post-buckling response of the FGM beams.