• Steel and Composite Structures
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• 제20권3호
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• pp.599-621
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• 2016

In order to study the working mechanism of rectangular steel-concrete composite columns subjected to compression-bending load and further determine the seismic performance index, a bottom strengthened rectangular steel reinforced concrete (SRC) column with concealed steel plates and a bottom strengthened rectangular concrete filled steel tube (CFST) columns were proposed. Six column models with different configurations were tested under horizontal low cyclic loading. Based on the experiments, the load-bearing capacity, stiffness and degradation process, ductility, hysteretic energy dissipation capacity, and failure characteristics of the models were analyzed. The load-bearing capacity calculation formulas for a normal section and an oblique section of bottom strengthened rectangular steel-concrete composite columns were pesented and a finite element (FE) numerical simulation of the classical specimens was performed. The study shows that the load-bearing capacity, ductility, and seismic energy dissipation capacity of the bottom strengthened rectangular steel-concrete composite columns are significantly improved compared to the conventional rectangular steel-concrete composite columns and the results obtained from the calculation and the FE numerical simulation are in good agreement with those from the experiments. The rectangular steel-concrete composite column with bottom strengthened shows better seismic behavior and higher energy dissipation capacity under suitable constructional requirements and it can be applied to the structure design of high-rise buildings.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1363-1373
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• 2022

The recent seismic events that occurred in South Korea have increased the interest in the re-evaluation of the seismic capacity of nuclear power plant (NPP) equipment, which is often conservatively estimated. To date, various approaches-including the Bayesian method proposed by the United States (US) Electric Power Research Institute -have been developed to quantify the seismic capacity of NPP equipment. Among these, the Bayesian approach has advantages in accounting for both prior knowledge and new information to update the probabilistic distribution of seismic capacity. However, data availability and region-specific issues exist in applying this Bayesian approach to Korean NPP equipment. Therefore, this paper proposes to construct an earthquake experience database by combining available earthquake records at Korean NPP sites and the general location of equipment within NPPs. Also, for the better representation of the seismic demand of Korean earthquake datasets, which have distinct seismic characteristics from those of the US at a high-frequency range, a broadband frequency range optimization is suggested. The proposed data construction and seismic demand optimization method for seismic capacity re-evaluation are demonstrated and tested on a 480 V motor control center of a South Korea NPP.

• 한국지구과학회지
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• 제33권5호
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• pp.395-400
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• 2012

One of the main problems concerning the shallow seismic survey is how to generate high frequency signals with large amplitudes using small seismic sources. If one could focus the seismic energy in the direction of the survey line, it will be much helpful in identifying the first break. In this research, we have used hammer as an impulsive source and compared the signal powers generated by different shapes of the hammer plates: circular, square, and rectangular. The experiment was conducted by calculating the power spectral density function to compare the frequency spectrum and signal power. In the direction perpendicular to the long side of the rectangular plate, the largest seismic energy with the highest frequency was achieved even with the same weights of hammer plates. Our conclusion is that it is more efficient to use a rectangular plate than a circular (or square) one when conducting a 2-D shallow seismic survey.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.105-108
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• 2005

In damage investigation of building structures suffering from earthquake, estimation of residual seismic capacity is essential in order to access the safety of the building against aftershocks and to judge the necessity of repair and restoration. It has been proposed that an evaluation method for post-earthquake seismic capacity of reinforced concrete buildings based. on the residual energy dissipation capacity (the residual seismic capacity ratio )in lateral force-displacement curve of structural members. The proposed method was adopted in the Japanese 'Damage Level Classification Standard' revised in 200l. To evaluate the residual seismic capacity of RC column, experimental tests with positive and negative cyclic loading was carried out using RC building column specimen. Parameters used by the experiment are deformability and member proportion. From the test results, it is appropriated that the residual seismic capacity of RC buildings damaged by earthquakes is evaluated using the method in the Guideline.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.466-472
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• 1996

The nonlinear analysis was perforned for a 2-bay 2-story moment-resisting reinforced concrete plane frame with seismic detail using KDARC 2D program. The analytical models consist of the material model, the member model, the hysteretic model, and the damage model etc. The conclusion based on the results of analysis is as following. : (1) Story shear-displacement relationship is similar to the experiment result but from the energy point of view, the analysis relationship is similar to the experiment result but from the energy point of view, the analysis result was different from the experiment result. (2) Plastic hinges were found to occur mainly in beams at first story while all the columns had plastic hinges throughout the structure. (3) Failure mode is a little different from experiment result in the yielding mechanism. (4) Damage index isabout 0.25. This means that the degree of damage is moderate and can be repairable.

• Steel and Composite Structures
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• 제19권3호
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• pp.547-567
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• 2015

The paper makes the experimental and finite-element-analysis investigation on the seismic behavior of the rebar-penetrated joint between gangue concrete filled steel tubular column and reinforced gangue concrete beam under low cyclic reversed loading. Two specimens are designed and conducted for the experiment to study the seismic behavior of the rebar-penetrated joint under cyclic loading. Then, finite element analysis models of the rebar-penetrated joint are developed using ABAQUS 6.10 to serve as the complement of the experiment and further analyze the seismic behavior of the rebar-penetrated joint. Finite element analysis models are also verified by the experimental results. Finally, the hysteretic performance, the bearing capacity, the strength degradation, the rigidity degradation, the ductility and the energy dissipation of the rebar-penetrated joint are evaluated in detail to investigate the seismic behavior of the rebar-penetrated joint through experimental results and finite element analysis results. The research demonstrates that the rebar-penetrated joint between gangue concrete filled steel tubular column and reinforced gangue concrete beam, with full and spindle-shaped load-displacement hysteretic curves, shows generally the high ductility and the outstanding energy-dissipation capacity. As a result, the rebar-penetrated joint exhibits the excellent seismic performance and meets the earthquake-resistant requirements of the codes in China. The research provides some references and suggestions for the application of the rebar-penetrated joint in the projects.

• 교육시설 논문지
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• 제19권4호
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• pp.21-28
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• 2012

This study proposes a procedure for evaluating the seismic performance and retrofit of a typical reinforced building (R/C) school buildings contructed in the 1980s. The procedure is derived from the Japanese Standard for Evaluation of Seismic Capacity of Existing Reinforced Concrete Buildings and Nonlinear Static Procedure (NSP) specified in Federal Emergency Management Agency (FEMA 356). In this study, the Japanese Standard was applied for evaluating the additionally required seismic performance in the existing school building. Cast-in-place (CIP) reinforced concrete infill walls and steel braces were used to seismically retrofit the existing school building located in the region of Hongsung in Chungnam. In the pushover analysis, i.e NSP, the hinge properties of columns, beams, infill walls and steel braces were carefully calibrated based on the existing experiment results in the available literatures. The predicted seismic performance for the retrofitted building was compared to that for the virgin building. Based on the seismic evaluation with the Japanese Standard and the FEMA 356 criteria, the addition of CIP reinforced concrete infill walls and steel braces have superior constructablility and can improve effectively the seismic performance of the existing school buildings constructed in 1980s.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.427-430
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• 2005

The study for seismic characteristics of square concrete-filled steel tubular (CFT) columns is analytically conducted. For predicting the strength and ductility of CFT columns, fiber analysis technique is used. The analytical results show reasonable agreement with experiment results. The influence of the steel tube on the lateral response of CFT columns is studied for the evaluation of seismic performance.

• Structural Engineering and Mechanics
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• 제16권4호
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• pp.371-390
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• 2003

The concept of the seismic slit shear wall was proposed in the early 1990's. A series of experimental and theoretic studies on the wall with reinforced concrete short connecting beams cast in the slit were carried out. In this paper another type of slit shear wall is studied. It is one with vertical slit purposely cast within the wall, and the rubber belt penetrated by a part of web shear reinforcement as seismic energy-dissipation device is filled in the slit. Firstly, an experiment under cyclic loading was carried out on two shear wall models, one slit and the other solid. The failure mechanism and energy-dissipation capacity are compared between the two different models, which testifies the seismic performance of the slit wall improved significantly. Secondly, for engineering practice purpose, a macroscopic analytical model is developed to predict the nonlinear behavior of the slit shear wall under cyclic loading. The mechanical properties of each constituent elements of this model are based on the actual behavior of the materials. Furthermore, the effects of both the axial force and bending moment on the shear behavior are taken into account with the aid of the modified compression-field theory. The numerical results are verified to be in close agreement with the experimental measurements.

• 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.