• Steel and Composite Structures
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• 제24권4호
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• pp.409-423
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• 2017

This paper presents an experimental study on damage evolution laws of solid-web steel reinforced concrete (SRC) T-shaped columns along the direction of the web under various loadings. Ten specimens with a scale ratio of 1/2 and a shear span ratio of 2.5 were designed and fabricated. The influences of various parameters, including the axial compression ratio, steel ratio, and loading mode, were examined. The mechanical performances including load-displacement curve and energy dissipation capacity under the monotonic and low cyclic loadings were analyzed. Compared with the monotonic loading, bearing capacity, ultimate deformation capacity, and energy dissipation capacity of the specimens decrease to some extent with the increase of the displacement amplitude and the number of loading cycle. The results show that the damage process of the SRC T-shaped column can be divided into five stages, namely non-damage, slight-damage, steadily-developing-damage, severe-damage and complete-damage. Finally, based on the Park-Ang model, a modified nonlinear damage model which combines the maximum deformation with hysteretic energy dissipation is proposed by taking into account the dynamic influence of the aforementioned parameters. The results show that the modified model in this paper is more accurate than Park-Ang model and can better describe the damage evolution of SRC T-shaped columns.

• 한국구조물진단유지관리공학회 논문집
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• 제19권5호
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• pp.112-119
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• 2015

본 논문에서는 기둥이 취약한 골조의 내진성능을 향상시키기 위한 공법을 제안하였다. 이를 위하여 기둥을 아라미드 시트로 횡구속하여 취성적인 특성을 개선하였으며, S형 스트럿을 가지는 강재 댐퍼를 설치하여 에너지 소산 능력을 증진시켰다. 비보강 실험체 및 보강 실험체를 실물크기로 제작하여 수평하중 저항 능력을 평가하였다. 파괴 양상, 강도, 강성 저하 및 에너지 소산 능력 등에서 보강 실험체의 효과를 확인할 수 있었다. 또한 ABAQUS를 이용한 FE 해석으로부터, 대상 실험체의 이력 거동을 예측 및 평가하였다.

• Steel and Composite Structures
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• 제32권2호
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• pp.265-279
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• 2019

The self-centering capacity and energy dissipation performance have been recognized critically for increasing the seismic performance of structures. This paper presents an innovative steel moment frame with self-centering steel reinforced concrete (SRC) wall panel incorporating replaceable energy dissipation devices (SF-SCWD). The self-centering mechanism and energy dissipation mechanism of the structure were validated by cyclic tests. The earthquake resilience of wall panel has the ability to limit structural damage and residual drift, while the energy dissipation devices located at wall toes are used to dissipate energy and reduce the seismic response. The oriented post-tensioned strands provide additional overturning force resistance and help to reduce residual drift. The main parameters were studied by numerical analysis to understand the complex structural behavior of this new system, such as initial stress of post-tensioning strands, yield strength of damper plates and height-width ratio of the wall panel. The static push-over analysis was conducted to investigate the failure process of the SF-SCWD. Moreover, nonlinear time history analysis of the 6-story frame was carried out, which confirmed the availability of the proposed structures in permanent drift mitigation.

• 한국지진공학회논문집
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• 제20권6호
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• pp.351-360
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• 2016

In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length($40d_b$ and $50d_b$) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.

• 콘크리트학회논문집
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• 제19권1호
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• pp.103-111
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• 2007

본 연구는 강섬유 보강 콘크리트와 앵글을 사용한 합성보의 구조성능을 평가하고자 실험 연구를 수행하였다. 이러한 목적으로 일반 RC보와 강섬유가 혼입된 RC보, 그리고 강섬유 보강 합성보로 구성된 총 7개의 실험체를 제작하였으며, 모든 실험체에는 별도의 전단보강을 하지 않았다. 실험체의 주요 변수는 강섬유의 혼입률과 인장보강근비이며, 합성보의 강도 예측식의 평가와 실험 결과로부터 합성보의 강도, 강성, 연성능력, 에너지소산능력 등의 구조 성능을 평가하였다. 실험 결과들을 평가한 결과, 합성보의 공칭강도 산정식은 매우 정확한 예측이 가능하였으며, 휨균열강도 예측식은 강섬유 보강 효과의 고려가 필요하다고 판단되었다. 강섬유 체적비는 실험체의 강도와 연성 능력, 그리고 에너지소산 능력을 모두 증가시키는 것으로 나타났다. 인장보강근비와 유효인장보강근비의 증가는 실험체의 최대강도 증가에는 효과가 있지만, 반면에 연성 능력과 에너지소산 능력은 일정 수준을 초과하면 연성 능력과 에너지소산 능력이 저하하는 것으로 나타나고 있으므로 적절한 인장보강근비와 유효인장보강근비가 적용될 수 있도록 제한할 필요성이 있다고 판단된다.

• 한국강구조학회 논문집
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• 제18권4호
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• pp.457-468
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• 2006

얇은 웨브강판을 사용한 전단지배 강판벽의 최대 에너지소산능력 및 연성능력을 연 구하기 위한 실험 연구를 실시하였다. 이를위해서 얇은 강판을 사용한 3층 골조 강판벽 실험을 수행하였다. 주요 실험 변수는 강판의 형상비와 기둥 단면의 전단강도이며, 골조 강판벽 시스템의 상대적 비교를 위해 중심가새골조 및 모멘트저항골조와의 비교실험을 실시하였다. 골조 강판벽 실험체는 중심가새골조와 모멘트저항골조 실험체에 비하여 매우 우수한 연성도와 에너지소산능력을 나타냈다. 따라서 전단지배형 골조강판벽은 큰 강도, 강성 및 변형능력을 동시에 달성할 수 있는 이상적인 내진구조시스템으로 사용할 수 있다. 전단지배 강판벽의 주기거동을 예측하기 위하여, 본 연구의 실험결과와 기존 실험결과를 토대로 강판벽의 에너지소산능력을 예측할 수 있는 방법을 제시하였다.

• Steel and Composite Structures
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• 제22권2호
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• pp.449-472
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• 2016

This paper studies the seismic behavior of reinforced concrete (RC) walls with encased cold-formed and thin-walled (CFTW) steel truss, which can be used as an alternative to the conventional RC walls or steel reinforced concrete (SRC) composite walls for high-rise buildings in high seismic regions. Seven one-fourth scaled RC wall specimens with encased CFTW steel truss were designed, manufactured and tested to failure under reversed cyclic lateral load and constant axial load. The test parameters were the axial load ratio, configuration and volumetric steel ratio of encased web brace. The behaviors of the test specimens, including damage formation, failure mode, hysteretic curves, stiffness degradation, ductility and energy dissipation, were examined. Test results indicate that the encased web braces can effectively improve the ductility and energy dissipation capacity of RC walls. The steel angles are more suitable to be used as the web brace than the latticed batten plates in enhancing the ductility and energy dissipation. Higher axial load ratio is beneficial to lateral load capacity, but can result in reduced ductility and energy dissipation capacity. A volumetric ratio about 0.25% of encased web brace is believed cost-effective in ensuring satisfactory seismic performance of RC walls. The axial load ratio should not exceed the maximum level, about 0.20 for the nominal value or about 0.50 for the design value. Numerical analyses were performed to predict the backbone curves of the specimens and calculation formula from the Chinese Code for Design of Composite Structures was used to predict the maximum lateral load capacity. The comparison shows good agreement between the test and predicted results.

• 한국공간구조학회논문집
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• 제6권2호
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• pp.131-136
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• 2006

It is important to evaluate energy absorption capacity of frames required during a design earthquake. An inelastic computer analysis based on mathematical modelling of energy absorbing frames and elements makes it possible to evaluate required energy absorption capacity. But such an analysis sometimes consumes much computation time particularly in case of complicated structural system. This paper presents a proposal to predict energy absorption of multi-bent steel frames by simple equivalent linear method.

• Steel and Composite Structures
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• 제27권4호
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• pp.417-426
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• 2018

This paper presents the seismic behaviors and restoring force model of ring beam joints of steel tube-reinforced concrete column structure under cyclic loading. First, the main failure mode, ultimate bearing capacity, stiffness degradation and energy dissipation capacity are studied. Then, the effects of concrete grade, steel grade, reinforcement ratio and radius-to-width ratios are discussed. Finally, the restoring force model is proposed. Results show that the ring beam joints of steel tube-reinforced concrete column structure performs good seismic performances. With concrete grade increasing, the ultimate bearing capacity and energy dissipation capacity increase, while the stiffness degradation rates increases slightly. When the radius-width ratio is 2, with reinforcement ratio increasing, the ultimate bearing capacity decreases. However, when the radius-to-width ratios are 3, with reinforcement ratio increasing, the ultimate bearing capacity increases. With radius-to-width ratios increasing, the ultimate bearing capacity decreases slightly and the stiffness degradation rate increases, but the energy dissipation capacity increases slightly.

• Computers and Concrete
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• 제19권3호
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• pp.227-232
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• 2017

This paper describes an experimental study of the cyclic performance of concrete beams reinforced with CFRP prestressed concrete prisms (PCP). The failure modes, hysteretic loops, skeleton curve, ductility, energy dissipation capacity and stiffness degradation of concrete beams reinforced with CFRP prestressed concrete prisms were analyzed. The results show that The CFRP prestressed prisms reinforced concrete beams have good seismic performance. The level of effective prestress and cross section of CFRP prestressed prisms had a little influence on the bearing capacity, the ductility and energy dissipation capacity of CFRP prestressed prisms reinforced concrete beams.