• Steel and Composite Structures
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• 제1권2호
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• pp.201-212
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• 2001

In order to investigate the effect of the loading rate on the mechanical behavior of SRC shearwalls, we conducted the lateral loading tests on the 1/3 scale model shearwalls whose edge columns were reinforced by H-shaped steel. The specimens were subjected to the reversed cyclic lateral load under a variable axial load. The two types of loading rate, 0.01 cm/sec for the static loading and 1 cm/sec for the dynamic loading were adopted. The failure mode in all specimens was the sliding shear of the in-filled wall panel. The edge columns did not fail in shear. The initial lateral stiffness and lateral load carrying capacity of the shearwalls subjected to the dynamic loading were about 10% larger than those subjected to the static loading. The effects of the arrangement of the H-shaped steel on the lateral load carrying capacity and the lateral load-displacement hysteresis response were not significant.

• 한국지반공학회논문집
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• 제33권10호
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• pp.59-69
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• 2017

지반내 근입된 앵커의 인장력은 시간이 경과하면서 점차 변화하게 되는데 이때 초기 인장력의 변화는 보통 정착헤드의 정착조건과 인장자재의 기계적 특성에 의해 1차적으로 감소하게 되며, 이후 추가적인 인장력의 변화는 대부분 정착장의 정착조건과 주변 지반특성에 기인한 시간의존적인 정착거동에 좌우된다. 따라서 본 논문에서는 이러한 인장력 변화를 비교적 쉽게 측정 및 분석할 수 있는 상대변위측정기를 이용한 측정시스템에 대해서 연구하였다. 검토결과 실규모 모형시험을 통해서 본 측정시스템의 적용성을 확인 하였으며, 또한 풍화암에 정착된 지반앵커를 대상으로 실시한 현장 시험결과와도 유사함을 확인함에 따라 본 측정시스템의 적용성을 확인하였다. 그리고 초기인장력이 비교적 크게 감소된 시험앵커를 대상으로 추가적인 인발시험을 실시하였으며 이를 통해 인장형 앵커의 인발거동을 확인하였다.

• 한국전산구조공학회논문집
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• 제15권3호
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• pp.481-490
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• 2002

본 논문의 목적은 공간 트러스 비선형 해석기법에 대한 수치해석적 장단점을 비교하고, 효율적인 해석기법을 제안하는 것이다. 사용된 해석기법은 하중 제어법으로 뉴턴-랩슨법, 수정 뉴턴-랩슨법, 할선-뉴턴법, 하중-변위 제어법으로 호장법, 증분일 제어법, 그리고 본 논문에서 제안한 하중-변위의 복합적 제어법으로 복합 호장법 Ⅰ, 복합 호장법Ⅱ, 복합 증분일 제어법이 있다. 공간 트러스에 대한 해석기법의 효율성 평가를 위하여 해의 정확성, 수렴성, 계산시간 등을 제시된 예에 비교한 결과 본 논문에서 제안한 하중-변위의 복합적 제어법의 신뢰성을 입증하였으며, 기하학적 비선형 해석 및 좌굴후 거동의 추적에 있어서 효율적이었다. 특히, 자유도수가 많은 공간 트러스의 좌굴하중 추척에 있어서는 복합 증분일 제어법이 효율적이었다.

• Structural Engineering and Mechanics
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• 제80권6호
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• pp.749-765
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• 2021

Suspension bridges bear large eccentric live loads in rush hours when most vehicles travel in one direction on the left or right side of the bridge. With the increasing number and weight of vehicles and the girder widening, the eccentric live load effect on the bridge behavior, including bending and distortion of the main girder, gets more pronounced, even jeopardizing bridge safety. This study proposes an analytical algorithm based on multi-catenary theory for predicting the suspension bridge responses to eccentric live load via the nonlinear generalized reduced gradient method. A set of governing equations is derived to solve the following unknown values: the girder rigid-body displacement in the longitudinal direction; the horizontal projection lengths of main cable's segments; the parameters of catenary equations and horizontal forces of the side span cable segments and the leftmost segments of middle span cables; the suspender tensions and the bearing reactions. Then girder's responses, including rigid-body displacement in the longitudinal direction, deflections, and torsion angles; suspenders' responses, including the suspender tensions and the hanging point displacements; main cables' responses, including the horizontal forces of each segment; and the longitudinal displacement of the pylons' tower top under eccentric load can be calculated. The response of an exemplar suspension bridge with three spans of 168, 548, and 168 m is calculated by the proposed analytical method and the finite element method in two eccentric live load cases, and their results prove the former's feasibility. The nonuniform distribution of the live load in the lateral direction is shown to impose a greater threat to suspension bridge safety than that in the longitudinal direction, while some other specific features revealed by the proposed method are discussed in detail.

• 한국방재학회 논문집
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• 제5권4호
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• pp.49-57
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• 2005

본 연구에서는 상재하중을 적용한 굴착모형실험을 통하여 상재하중 적용으로 인한 굴착단계별, 벽체강성 및 지반조건에 따른 토류벽체의 수평변위, 배면지반 지표침하, 토류벽체에 적용되는 토압변화 및 분포에 대하여 실험결과치, 이론치 및 현장자료 분석치와 상호비교, 분석하여 상재하중 적용에 의한 영향을 규명하였다. 그 결과 상재하중이 적용된 모형지반에서의 지표침하곡선 형태는 상재하중 미 적용시 지표침하 곡선형태의 정규확률 분포곡선과 달리 상재하중 중앙 부분이 최대 침하를 일으키는 포물선 형태의 침하를 보이고 있으며, 굴착단계별 상재하중 적용으로 인한 벽체최대수평변위는 최종굴착시에 0.8H(보:굴착깊이) 지점에서 벽체의 최대수평변위가 발생하였으며, 상재하중 적용에 따른 벽체변위량의 증가범위는 벽체상부로부터 하중이격거리에 2배의 깊이까지 증가범위를 보였다. 또한, 굴착단계별 지표면의 침하로 인한 기초판의 각 변위는 최종단계에서의 각 변위가 가장 크게 발생하였고, 벽체강성별로는 두께 4mm(유연계수 ${\rho}\;:480m^3/t$) 벽체가 두께 9mm(유연계수 ${\rho}\;: 40m^3/t$)보다 최대 3배 이상 발생하고 있어 벽체강성의 영향이 매우 큼을 알 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.475-480
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• 2003

Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.

• 한국산학기술학회논문지
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• 제17권3호
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• pp.432-437
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• 2016

본 연구는 금속 주름관, 내부 스프링, 금속마개 등으로 구성된 소형 벨로우즈 세트의 거동에 대하여 연구하였다. 벨로우즈는 자동차용 에어컨의 제어를 위한 전자기제어밸브의 핵심 부품으로써 기계적 하중과 외부 압력에 대하여 민감하고 정확하게 작동하여야 한다. 벨로우즈 설계 인자 도출을 위하여, 소형 인장시험기를 이용하여 벨로우즈 내부 스프링의 스프링 상수를 측정하고, 벨로우즈 세트의 하중-변위 선도를 측정하였다. 내부 스프링의 하중-변위 관계는 선형관계를 나타내었다. 벨로우즈 세트의 하중-변위 관계는 변위가 작을 때는 낮은 기울기를 가지고 하중이 증가하다가 이후 선형으로 증가하는 특성을 나타내었다. 실측 결과를 바탕으로 유한요소해석을 수행하여 외부 주름관의 유효 물성을 도출하고 유한요소 모델링을 확보하였다. 원통형의 형상을 고려하여 축대칭 모델을 적용하였으며, 주름관은 쉘 요소를 적용하였다. 확보한 모델을 활용하여 냉매 압력에 따른 벨로우즈의 거동에 대한 연구를 수행하였다.

• Steel and Composite Structures
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• 제18권1호
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• pp.29-50
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• 2015

With a quasi-three point bending apparatus, ratcheting deformation is studied experimentally on a pressurized austenitic stainless steel Z2CND18.12N pipe under bending load and vertical displacement control, respectively. The characteristic of ratcheting behavior of straight pipe under both control methods is achieved and compared. The cyclic bending loading and internal pressure influence ratcheting behavior of pressurized straight pipe significantly under loading control and the ratcheting characteristics are also highly associated with the cyclic displacement and internal pressure under displacement control. They all affect not only the saturation of the ratcheting strain but the ratcheting strain rate. In addition, ratcheting simulation is performed by elastic-plastic finite element analysis with ANSYS in which the bilinear model, Chaboche model, Ohno-Wang model and modified Ohno-Wang model are applied. By comparison with the experimental data, it is found that the CJK model gives reasonable simulation. Ratcheting boundaries under two control modes are almost same.

• Earthquakes and Structures
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• 제1권1호
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• pp.21-41
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• 2010

Multi-span steel-concrete composite (SCC) bridges are very sensitive to earthquake loading. Extensive damage may occur not only in the substructures (piers), which are expected to yield, but also in the other components (e.g., deck, abutments) involved in carrying the seismic loads. Current seismic codes allow the design of regular bridges by means of linear elastic analysis based on inelastic design spectra. In bridges with superstructure transverse motion restrained at the abutments, a dual load path behavior is observed. The sequential yielding of the piers can lead to a substantial change in the stiffness distribution. Thus, force distributions and displacement demand can significantly differ from linear elastic analysis predictions. The objectives of this study are assessing the influence of piers-deck stiffness ratio and of soil-structure interaction effects on the seismic behavior of continuous SCC bridges with dual load path, and evaluating the suitability of linear elastic analysis in predicting the actual seismic behavior of these bridges. Parametric analysis results are presented and discussed for a common bridge typology. The response dependence on the parameters is studied by nonlinear multi-record incremental dynamic analysis (IDA). Comparisons are made with linear time history analysis results. The results presented suggest that simplified linear elastic analysis based on inelastic design spectra could produce very inaccurate estimates of the structural behavior of SCC bridges with dual load path.

• 한국환경복원기술학회지
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• 제10권4호
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• pp.31-40
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• 2007

Recently, the scale in the field of reinforced soil retaining wall has been grown up like tiered reinforced soil retaining wall. However, there have been increasing number of collapse accidents and large scale of collapse. The design manual adopted in the construction fields have been inconsistent in tiered reinforced soil retaining wall. Therefore, this study performed finite element analysis on 90 cases and analyzed characteristic behavior of lower wall which was one of the effect factors on the stability of tiered reinforced soil retaining wall. The facing displacement of each walls and the behavior of the whole ground were interpreted by the numerical analysis depending on the lower offset distance by the upper wall as well as the upper offset distance by the surcharge load. The results showed that the behavior of tiered reinforced soil retaining wall was differed by condition of surcharge load and each offset distance was found to be important factor.