• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.439-447
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• 2005

When arch ribs are subjected to vertical loading, they may buckle suddenly towards the in-plane direction. Therefore, the designer should consider their in-plane stability. In this paper, the in-plane elastic and inelastic buckling strength of parabolic, fixed arch ribs subjected to vertical distributed loading were investigated using the finite element method. A finite element model for the snap-through and inelastic behavior of arch ribs was verified using other researchers' test results. The ultimate strength of arch ribs was determined by taking into account their large deformation, material inelasticity, and residual stress. Finally, the finite element analysis results were compared with the EC3 design code.

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.251-259
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• 2003

In this paper, an analytical approach hwas been conductsed to clarify the relationships between the axial force and the deformation capacity of steel- encased reinforced- concrete beam-columns. The analytical model was defined as a cantilever. Several parameters influencing the inelastic performance of the beam-columns were selected, as follows: including encased steel area ratios, and sectional shapes of the encased steel, material strengths, and shear-span- to-depth ratios. The Analytical results of the analysis showed that the axial force had to have a maximum limit to ensure the stable behavior of a steel- encased reinforced- concrete beam-column when it was subjected to both axial and repeated lateral loading under a constant rotation angle amplitude. The maximum axial force of the beam-column to be resisted under cyclic lateral loading was defined as the stable-limit axial force to ensure the required rotation angle amplitude. The Analytical results of the analysis indicate that the stable-limit axial load ratio increases as the steel strength increases or as the compressive strength of the concrete decreases. The stable-limit axial load ratio decreases as the encased steel ' s sectional area increases in the case of a 1-shaped sections and it is almost not influenced by the steel sectional area in the case of a cross-shaped section.

• Computational Structural Engineering
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• v.6 no.3
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• pp.67-80
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• 1993

This paper presents the results of an analytical study to evaluate the inelastic seismic response characteristics of multistory building structures, the effects of gravity load on the seismic responses and its implications on the earthquake resistant design. Static analyses for incremental lateral force and nonlinear dynamic analyses for earthquake motions were performed to evaluate the seismic response of example multistory building structures. Most of considerations are placed on the distribution of inelastic responses over the height of the structure. When an earthquake occurs, bending moment demand is increased considerably from the top to the bottom of multistory structures, so that differences between bending moment demands and supplies are greater in lower floos of multistory structures. As a result, for building structures designed by the current earthquake resistant design procedure, inelastic deformations for earthquake ground motions do not distribute uniformly over the height of structures and those are induced mainly in bottom floors. In addition, gravity load considerded in design procedure tends to cause much larger damages in lower floors. From the point of view of seismic responses, gravity load affects the initial yield time of griders in earlier stage of strong earthquakes and results in different inelastic responses among the plastic hinges that form in the girders of a same floor. However, gravity load moments at beam ends are gradually reduced and finally fully relaxed after a structure experiences some inelastic excursions as a ground motion is getting stronger. Reduction of gravity load moment results in much increased structural damages in lower floors building structures. The implications of the effects of gravity load for seismic design of multistory building structures are to reduce the contributions of gravity load and to increased those of seismic load in determination of flexual strength for girders and columns.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.97-105
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• 2001

Rubber bearings may exhibit a significant cold temperature effect and some velocity dependency(strain rate effect). Both of these attributes which affect non-linear behavior must be accounted for when accurately modeling the bearings behavior, therefore, an analytical models is proposed to consider the effects of the cold temperature and strain rate on both rubber and lead. From the results of an experimental investigation where the frozen bearings were tested under lateral cyclic loading with constant axial load, a non-linear system identification with least squares procedure was applied to determine the material properties of rubber and lead. It is demonstrated that the proposed analytical model is able to simulate the reversed cyclic loading behavior of elastometric and lead-rubber bearings.

• Computational Structural Engineering
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• v.7 no.1
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• pp.83-90
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• 1994

This study presents the nonlinear dynamic analysis method of the bridge with the seismic isolation bearing. Also the numerical analyses are performed for investigating the response characteristics of the bridge isolated with the lead-rubber bearing under the ground motions compatible to Korea bridge design response spectra. It is found that the pier design force can be considerably smaller than the one for the bridge with the fixed bearing. It is observed that the lead-rubber bearing has the great effectiveness for reducing the longitudinal seismic force in case of the bridges with low and medium periods. Therefore the seismic isolation bearing can be used instead of the fixed bearing for the economic and safe design of the bridge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5A
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• pp.475-484
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• 2010

The purpose of this study is to investigate the inelastic behavior of precast concrete copings for precast segmental PSC bridge columns and to provide the details and reference data. Twelve one-fourth-scale precast concrete copings were tested under quasistatic monotonic loading. In this study, the computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), was used. A joint element is modified to predict the inelastic behaviors of segmental joints. This study documents the testing of precast concrete copings for precast segmental PSC bridge columns and presents conclusions based on the experimental and analytical findings.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.155-155
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• 2011

일반적으로 I형 보에 횡하중이 작용하는 경우, 횡 변위와 함께 회전을 동반하는 횡-비틀림 좌굴(Lateral-Torsional Buckling)이 발생하게 된다. 이러한 I형 보의 탄성 및 비탄성 횡-비틀림 좌굴에 대한 해석적 이론적 연구는 이미 많은 연구자들에 의해 수행되었다(Timoshenko 등, 1961; Galambos, 1963; Lindner, 1974; Trahair, 1993). I형 보의 비지지 길이 내 하중이 작용할 때 모멘트 구배계수(Cb)는 하중이 부재 단면에 작용하는 위치에 따라 달라지게 되는데 이를 하중고 효과(Load Height Effects)라고 한다. 탄성 영역 내 비지지길이가 존재하는 I형 보의 하중고 효과를 고려한 모멘트 구배계수 제안식은 Nethercot & Rockey(1971)에 의해 연구된 바 있다. 또한 Helwig 등(1997)은 Nethercot & Rockey(1971)의 제안식을 간략화 하여 탄성 영역 내 비지지길이가 존재하는 I형 보의 하중고 효과를 고려한 모멘트 구배계수식을 제안하였다. 그러나 현재까지 진행 된 하중고 효과에 대한 연구는 탄성 영역 내 비지지 길이가 존재하는 I형 보에 대한 제안식이며 현재까지 비탄성 영역 내 비지지 길이를 갖는 I형 보의 하중고 효과에 대한 연구는 진행된 바 없다. 본 연구는 비탄성 영역 내 비지지 길이가 존재하는 I형 보의 하중고 효과를 고려한 비탄성 횡-비틀림 좌굴강도에 대한 연구를 수행하였다. 하중조건으로는 집중하중 과 등분포 하중을 적용시켰으며, 비선형 횡-비틀림 좌굴 해석을 위해 잔류응력 및 초기변형을 고려하였다. Pi와 Trahair(1995)이 고려한 단순직선분포를 잔류응력으로 가정하였으며, 국내 I형강 표준 치수 허용치(현대제철, 2006)에 근거하여 부재 길이의 0.1%를 초기 최대 횡 변위로 적용하여 초기제작오차로 고려하였다. 유한요소해석결과를 바탕으로 Nethercot & Rockey(1971)와 Helwig 등(1997)의 연구내용을 바탕으로 범용구조해석 프로그램(ABAQUS, 2007)을 이용하여 비탄성 영역 내 존재하는 I형보의 횡-비틀림 좌굴강도를 산정하였다. 유한요소해석결과를 바탕으로 Nethercot & Rockey(1971)및 Helwig 등(1997)의 모멘트구배계수 제안식과 비교 분석 하였고 회기분석프로그램 MINITAB(2006)을 이용하여 비탄성 영역 내 비지지길이가 존재하는 I형보의 하중고 효과를 고려한 모멘트구배계수식을 개발 제안하였다. 본 연구에서 개발된 제안식은 경제적이고 합리적인 휨부재 강도평가에 적극 활용될 수 있으며, 비탄성 영역내 I형보의 횡-비틀림 좌굴강도 및 휨강도 연구에 널리 활용될 것이다.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.503-513
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• 2007

The seismic responses of a building are affected by the connection characteristics that have effects on structural stiffness. In this study, push-over analysis and time history analysis were performed to estimate structural behavior of 2D eight-story unbraced steel structures with partially restrained composite connections using a nonlinear dynamic analysis program. Nonlinear $M-{\theta}$characteristics of connection and material inelastic characteristics of composite beam and steel column were considered. The idealization of composite semi-rigid connection as fully rigid connection yielded an increase in initial stiffness and ultimate strength in the push-over analysis. In time history analysis, the stiffness and hysteretic behavior of connections have effects on base-shear force, maximum story-drift and maximum moment in beams and columns. For seismic waves with PGA of 0.4 g, the structure with the semi-rigid composite connections shows the maximum story-drift with less than the life safety criteria by FEMA 273 and no inelastic behavior of beam and column, whereas in the structure with rigid connections, beams and columns have experienced inelastic behaviors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4216-4222
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• 2011

In this study the inelastic behavior of the existing school buildings with infilled masonry walls is analysed by pushover method. The shear stiffness and strength of masonry wall is calculated from the prior experimets and verified by inelastic analysis. The height of infilled masonry wall affects the structural behavior. The higher the masonry wall height, the higher the initial shear stiffness and strength of masonry wall. As the cracks are developed, the strength of masonry wall is much decreased. The proposed inelastic analysis method shows similar results with the experiments and can be used as inelastic analysis model of reinforced concrete buildings with infilled masonry walls.

• Journal of the Korean Geophysical Society
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• v.4 no.3
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• pp.219-226
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• 2001

본 연구에서는 주기적인 하중하에서의 철근콘크리트 기둥의 이력응답거동을 예측할 수 있는 해석적인 모델의 개발을 다루고 있다. 철근콘크리트 기둥의 비탄성 휨, 전단 및 휨-전단 변형은 개발된 모델을 통하여 주기적인 변위하에서 검토되었다. 개발된 모델들을 포함한 해석치와 실험치와의 비교분석을 통하여 본 연구에서 개발된 모델들의 검증을 실시하였고, 이 비교분석을 통하여 휨-전단간의 상호작용의 중요성을 강조하였으며, 본 연구에서 개발된 모델들의 정확성, 효율성 및 타당성을 입증하였다.