• Earthquakes and Structures
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• 제11권2호
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• pp.265-280
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• 2016

Environmental and operational benefits of green roofs are manifolds; however, their main disadvantages are cost and weight. New technology enabled the use of plastics to reduce the weight of green roof systems to promote their installation. To maximize their potential benefits, green roofs can be installed on existing structures. This study evaluates the influence of green roofs on the seismic response of 3, 6, and 8 storey reinforced concrete ductile moment resisting frames, which were designed according to current seismic standards, however, not designed for green roofs. For each frame, three different types of roofs are considered: gravel flat roof, extensive green roof, and intensive green roof. Nonlinear dynamic time history analysis using an ensemble of twenty real earthquake records was performed to determine the inter-storey drift demand and roof drift demand for each frame. Eigenvalue analysis was also performed to determine the impact of green roofs weight on the elastic and cracked periods of the structure. Results from the analysis demonstrated that intensive and extensive green roofs do not affect the seismic performance of reinforced concrete frame structures.

• 한국지진공학회논문집
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• 제28권2호
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• pp.85-92
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• 2024

This study presents code-compliant seismic details by addressing dry mechanical splices for precast concrete (PC) beam-column connections in the ACI 318-19 code. To this end, critical observations of previous test results on precast beam-column connection specimens with the proposed seismic detail are briefly reported in this study, along with a typical reinforced concrete (RC) monolithic connection. On this basis, nonlinear dynamic models were developed to verify seismic responses of the PC emulative moment-resisting frame systems. As the current design code allows only the emulative design approach, this study aims at identifying the seismic performances of PC moment frame systems depending on their emulative levels, for which two extreme cases were intentionally chosen as the non-emulative (unbonded self-centering with marginal energy dissipation) and fully-emulative connection details. Their corresponding hysteresis models were set by using commercial finite element analysis software. According to the current seismic design provisions, a typical five-story building was designed as a target PC building. Subsequently, nonlinear dynamic time history analyses were performed with seven ground motions to investigate the impact of emulation level or hysteresis models (i.e., energy dissipation performance) on system responses between the emulative and non-emulative PC moment frames. The analytical results showed that both the base shear and story drift ratio were substantially reduced in the emulative system compared to that of the non-emulative one, and it indicates the importance of the code-compliant (i.e., emulative) connection details on the seismic performance of the precast building.

• 한국전산구조공학회논문집
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• 제17권3호
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• pp.225-239
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• 2004

이 논문에서는 철근콘크리트 골조 구조물의 시공 시 작용하는 사하중, 활하중, 시공하중 등의 하중에 대한 지지 및 안전한 시공을 위해 설치되는 지지시스템에 대하여 보다 체계적인 분석이 이루어졌다. 지지시스템의 종류, 비계의 강성과 간격 등의 변화에 따른 구조물의 거동특성을 비교, 분석하였고, 기존의 설계규준 및 해석방법과의 비교를 위해 크리프 등의 시간의존적 거동을 고려한 경우와 괴려하지 않은 경우에 대하여 해석이 수행되었으며, 나무 비계를 사용한 경우와 강재 비계를 사용한 경우에 대한 비교 검토가 이루어졌다. 또한, 대표적인 3-경간 구조물에 대한 해석을 수행하여 내측 기둥과 외측 기둥의 부등축소에 따른 영향을 반영한 검토가 이루어졌다. 나아가 다양한 설계인자의 변화에 따른 거동분석을 통해 2SlR 지지시스템이 가장 효율적임을 제시하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제22권1호
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• pp.13-22
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• 2018

본 연구에서는 역V형 강재 가새로 보강된 기존 철근콘크리트 구조물의 내진보강 설계방법 개발을 위한 실험연구를 수행하였다. 보강되지 않은 철근콘크리트 골조 기준 실험체와 강재 가새를 사용하여 강도 및 강성을 향상시킨 보강 실험체를 제작하고 내진성능을 평가하였다. 가새 보강 실험체의 경우 강성이 약 2~3배 증가를 목표로 설계하였다. 내진성능평가 결과, 무보강 실험체는 기둥에서 많은 양의 콘크리트가 박리가 되었고, 가새 보강 실험체는 초기 설계 단계에서 목표로 한 성능수준을 보여주었다. 가새를 보강한 실험체의 경우, 무보강 실험체에 비하여 강성, 강도, 연성능력 그리고 에너지 소산 능력이 크게 향상되었다. 따라서 본 연구로부터의 실험결과를 토대로 기존 철근콘크리트 건축물의 가새 보강공법에 관한 설계법 및 설계절차 개발을 위한 기초자료로 활용하고자 한다.

• Earthquakes and Structures
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• 제24권5호
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• pp.365-375
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• 2023

Energy dissipation systems increase the energy dissipation capacity of buildings considerably. In this study, the effect of dampers on a typical 10-storey reinforced concrete structure with a ductile moment-resisting frame was investigated. In this context, 5 different models were created according to the calculation of the slip load and the positions of the dampers in the structure. Nonlinear time-history analyzes using 11 different earthquake acceleration records were performed on the models using the ETABS program. As a result of the analyses, storey displacements, energy dissipation ratios, drift ratios, storey accelerations, storey shears, and hysteretic curves of the dampers on the first and last storey and overturning moments are presented. In the study, it was determined that friction dampers increased the energy dissipation capacities of all models. In addition, it has been determined that positioning the dampers in the outer region of the structures and taking the base shear as a basis in the slip load calculation will be more effective.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.871-874
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• 2008

KBC 2005를 처음 적용할 때 많은 구조엔지니어들이 무량판 구조에 대한 횡력저항시스템 선정과이에 따른 상세적용에 많은 어려움이 있었다. 현재 KBC 2005에 대한 개정작업이 진행중에 있다. 이러한 시점에서 최근 개정 중인 건축구조기준의 개정안을 토대로 향후 개정안에 적용가능한 구조시스템을 미리 살펴볼 필요가 있다. KBC 2008(안)의 경우 내진설계범주에 따른 시스템의 높이제한, 특수전단벽과 같은 특수상세, 전단벽-골조 상호작용시스템과 같은 새로운 시스템의 도입으로 구조설계자가 현행 기준보다 시스템에 대하여 휠씬 더 다양한 선택이 가능할 것으로 판단된다.

• Structural Engineering and Mechanics
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• 제57권4호
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• pp.641-656
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• 2016

Reinforced concrete frame buildings with masonry infill walls are one of the most popular structural systems in the world. In most cases, the effects of masonry infill walls are not considered in structural models. The results of earthquakes show that infill walls have a significant effect on the seismic response of buildings. In some cases, the buildings collapsed as a result of the formation of a soft story. This study developed a simple method, called corner opening, by replacing the corner of infill walls with a very flexible material to enhance the structural behavior of walls. To evaluate the proposed method a series of experiments were conducted on masonry infill wall and reinforced concrete frames with and without corner openings. Two 1:4 scale masonry infill walls with and without corner openings were tested under diagonal tension or shear strength and two RC frames with full infill walls and with corner opening infill walls were tested under monotonic horizontal loading up to a drift level of 2.5%. The experimental results revealed that the proposed method reduced the strength of infill wall specimens but considerably enhanced the ductility of infill wall specimens in the diagonal tension test. Moreover, the corner opening in infill walls prevented the slid shear failure of the infill wall in RC frames with infill walls.

• Steel and Composite Structures
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• 제22권1호
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• pp.25-43
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• 2016

This paper presents the results of an experimental study investigating the effects of anchorage systems used in externally bonded steel plates on the strength and ductility of reinforced concrete structures. In the literature, diagonal steel plates bonded to frames were designed to be more flexible than the connections to eliminate the possible effect of the connection flexibility. However, to better evaluate the performance of the strengthened structures, the strength and behavior of connections should also be considered. The purpose of this study was to experimentally investigate the effects of different connection types of steel plates bonded to the frame using anchors on the strengthened RC structures. For this purpose, eleven specimens were designed to simulate the interior and exterior connection behavior. Two of these were used as the control beams and remaining nine for the investigation of the functionality of the end steel plates. Experimental results show that the load carrying capacity of the strengthened beams is directly related to the connection types of the steel plates. For the interior connections, L-shaped end plates that were strengthened using steel anchors must have adequate stiffness to prevent its shape. While, for the exterior connections, the connection with three anchors carried more load than the other exterior connections.

• Coupled systems mechanics
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• 제7권2호
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• pp.177-195
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• 2018

Reinforced concrete buildings in a seismically active area can be designed as DCM (medium ductility) or DCH (high ductility) class according to the regulations of Eurocode 8. In this paper, two RC buildings, one with a wall structural system and the other with a frame system, previously designed for DCM and DCH ductility, were analysed by using incremental dynamic analysis in order to study differences in the behaviour of structures between these ductility classes, especially the failure mechanism and ultimate collapse acceleration. Despite the fact that a higher behaviour factor of DCH structures influences lower seismic resistance, in comparison to DCM structures, a strict application of the design and detailing rules of Eurocode 8 in analysed examples caused that the seismic resistance of both frames does not significantly differ. The conclusions were derived for two buildings and do not necessarily apply to other RC structures. Further analysis could make a valuable contribution to the analysis of the behaviour of such buildings and decide between two ductility classes in everyday building design.

• Computers and Concrete
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• 제14권4호
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• pp.445-462
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• 2014

To solve structural optimization problems, it is necessary to integrate a structural analysis package and an optimization package. There have been many packages that can be employed to analyze reinforced concrete plane frames. However, because most structural analysis packages suffer from closeness of systems, it is very difficult to integrate them with optimization packages. To overcome the difficulty, we proposed a possible alternative, DAMDO, which integrates Design, Analysis, Modeling, Definition, and Optimization phases into an integration environment as follows. (1) Design: first generate many possible structural design alternatives. Each design alternative consists of many design variables X. (2) Analysis: employ the structural analysis software to analyze all structural design alternatives to obtain their internal forces and displacements. They are the response variables Y. (3) Modeling: employ artificial neural networks to build the models Y=f(X) to obtain the relationship functions between the design variables X and the response variables Y. (4) Definition: employ the design variables X and the response variables Y to define the objective function and constraint functions. (5) Optimization: employ the optimization software to solve the optimization problem consisting of the objective function and the constraint functions to produce the optimum design variables. The RC frame optimization problem was examined to evaluate the DAMDO approach, and the empirical results showed that it can be solved by the approach.