• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.69-75
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• 2005

In this paper, the comparative performance of repaired RC columns using steel and CFRP is presented. Also, the effect of transverse reinforcement ratio on the behavior of the steel and the CFRP repairing is investigated. Monotonic and cyclic load tests are conducted on nine RC column specimens with different repairing strategies and transverse reinforcement ratios to compare the load-displacement curves and the hysteretic behaviors. From the tests, it is observed that both steel and CFRP jacket repairings can significantly increase the displacement ductility and the ultimate load capacity of damaged columns.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.1
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• pp.35-43
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• 2009

Two types of piloti-type high-rise RC building structures having irregularity in the lower two stories were selected as prototypes, and nonlinear time history analysis was performed using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. One of the buildings studied had a symmetrical moment-resisting frame (BF), while the other had an infilled shear wall in only one of the exterior frames (ESW). A fiber model, consisting of concrete and reinforcing bar represented from the stress-strain relationship, was adapted and used to simulate the nonlinearity of members, and MVLEM (Multi Vertical Linear Element Model) was used to simulate the behavior of the wall. The analytical results simulate the behavior of piloti-type high-rise RC building structures well, including the stiffness and yield force of piloti stories, the rocking behavior of the upper structure and the variation of the axial stiffness of the column due to variation in loading condition. However, MVLEM has a limitation in simulating the abrupt increasing lateral stiffness of a wall, due to the torsional mode behavior of the building. The design force obtained from a nonlinear time history analysis was shown to be about $20{\sim}30%$ smaller than that obtained in the experiment. For this reason, further research is required to match the analytical results with real structures, in order to use nonlinear time history analysis in designing a piloti-type high-rise RC building.

• Computational Structural Engineering
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• v.11 no.1
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• pp.38-45
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• 1998

최근 국내외에서 활발히 개발되고 있는 지진격리 시스템은 원자력 발전소, 교량, 중요한 공공건물 등의 지진피해를 최소화하기 이하여 널리 적용되고 있다. 그리고 다른 방법에 비하여 경제성 및 효율성이 우수하기 때문에 관련 연구 및 응용이 활발히 진행되고 있다. 이에 따라 국내외에서 격리시스템의 비선형성과 구조물의 불연속성을 고려한 지진격리 구조물의 해석을 통한 거동을 규명하는 연구가 과거 수년간 활발히 진행되어 왔다. 당사(금호건설)는 상부하중 지지능력과 감쇠능력이 우수한 지진격리장치를 개발하였으며 지진격리장치를 설치한 교량의 지진해석을 수행하여 본 지진격리 시스템의 이론적 성능을 파악하였다. 본 수치해석은 CrayC94에 탑재된 비선형 해석에 뛰어난 것으로 알려진 ABAQU를 이용하였다. 본 지진격리 시스템은 적층고무받침(Laminated Rubber Bearing)과 PTFE 미끄럼받침으로 구성되어 있으며, 적층고무받침은 주로 복원력을 제공하며 PTFE 미끄럼받침은 상부하중을 지지하며 마찰감쇠를 제공하여 에너지를 소산하는 역할을 한다. 본 수치해석에서는 선형스프링과 마찰요소를 이용하여 각각을 모형화하였다. 개발된 지진격리 시스템이 주로 사용될 상판자중이 무거운 다경간 연속 PC Box Girder교를 모델교량으로 선택하여 해석을 수행하였으며 수치해석에 사용된 격리시스템의 사전에 수행된 동특성 실험결과를 활용하였다. 이러한 해석을 통하여 이론적 효율성을 파악할 수 있었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.55-62
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• 1999

For the efficient performance of steel and composite building structures subjected to strong earthquake, one of current research investigates the cyclic behavior of open-web composite beams. Both experimental test and nonlinear FEM analysis demonstrate their behavior so ductile that four T-sections around the corners of rectangular web-opening develop plastic hinges prior to potential brittle failure at the beam end, i.e. at the column face. This research proposes simplified equations for determining strength and initial stiffness of composite beams with a rectangular web-opening, and compares its results with those of experimental test and nonlinear FEM analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.85-88
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• 2008

The purpose of this study was to investigate the seismic behavior of precast concrete segmental bridge piers with shear resistance connecting structure. A model of precast concrete segmental bridge columns with shear resistance connecting structure was tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. The proposed numerical method for the seismic behavior of precast concrete segmental bridge piers with shear resistance connecting structure is verified by comparison with reliable experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.1-10
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• 1999

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential for the seismic design to perform the site specific ground response analysis. In this paper, the procedures of site specific ground response analysis were suggested based on the Korean seismic guideline and the review of state of the art technologies. The concept of ground response analysis was introduced, and the techniques of obtaining soil data for one dimensional equivalent linear analysis which include site investigation planning, field and laboratory testing techniques, deformational characteristics of soils at small to large strains, and site characterization techniques combining field and laboratory test results, were suggested. Finally, the case study was performed at Inchon area following the suggested procedure.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.23-31
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• 2010

It is necessary to develop reliable but simple analytical models to predict the nonlinear response of reinforced concrete wall structures. In this study, experimental results on the cyclic reversed lateral behaviors of reinforced concrete shear wall assemblages are simulated analytically by using the wall, beam, and column models available in the PERFORM 3D program. Through the comparison of experimental and analytical results, the reliability and limitations of the analysis are evaluated. In addition, the information, which could not be obtained experimentally, such as the internal flow of force, the contribution of the flange walls, and the resisting mechanism of the walls with the contribution of the coupling beam, is provided.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.77-84
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• 2006

Unlike homogeneous material structure, the behavior of masonry structure is not perfectly elastic even in the range of small deformations because it is a non-homogeneous and anisotropic composite structural material, consisting of masonry units, mortar, and grout. This paper proposes a simplified way of investigating the evolution of the deformation and damage of the structure subjected to a series of successive ground motions with varying shaking. Especially, the most simple but useful algorithm of Fast Fourier Transformation (FFT) has been adopted to investigate the evolution of the deformation and damage of the structure tested on the shaking table. Moreover, the development of a hi-linear curve for an equivalent SDOF system which is obtained by exploiting the frequency and stiffness relationship was discussed. Finally, some important findings related to inelastic properties of the URM are summarized.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.3
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• pp.11-26
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• 2011

The inelastic displacement ratio is defined as the ratio of the peak inelastic displacement to the peak linear elastic displacement. The inelastic displacement ratio allows simple evaluation of the peak inelastic displacement directly from the peak elastic displacement without computation of the inelastic response. Existing research of the inelastic displacement ratio is limited to piece-wise linear systems such as bilinear or stiffness degrading systems. In this paper, the inelastic displacement ratio is investigated for smooth hysteretic behavior systems subjected to near- and far-fault earthquakes. A simple formula of the inelastic displacement ratio is proposed by using a two step procedure of regression analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.537-549
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• 2001

The effect of partially restrained(PR) connections and the uncertainties in them on the reliability of steel frames subjected to seismic loading is addressed. A stochastic finite element method(SFEM) is proposed combining the concepts of the response surface method(RSM), the finite element method(FEM), the first-order reliability method (FORM), and the iterative linear interpolation scheme. The behavior of PR connections is captured using moment-relative rotation curves, and is represented by the four-parameter Richard model. For seismic excitation, the loading, unloading, and reloading behavior at PR connections is modeled using moment-relative rotation curves and the Masing rule. The seismic loading is applied in the time domain for realistic representation. The reliability of steel frames in the presence of PR connections is calculated considering all major sources of nonlinearity. The algorithm is clarified with the help of an example.