• Structural Engineering and Mechanics
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• 제25권4호
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• pp.365-382
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• 2007

A pilot study has been conducted to guide the development of a finite element modeling formulation for the analysis of architectural glass curtain walls under in-plane lateral load simulating earthquake effects. This pilot study is one aspect of ongoing efforts to develop a general prediction model for glass cracking and glass fallout for architectural glass storefront and curtain wall systems during seismic loading. For this study, the ANSYS finite element analysis program was used to develop a model and obtain the stress distribution within an architectural glass panel after presumed seismic movements cause glass-to-frame contact. The analysis was limited to static loading of a dry-glazed glass curtain wall panel. A mock-up of the glass curtain wall considered in the analysis with strain gages mounted at select locations on the glass and the aluminum framing was subjected to static loading. A comparison is made between the finite element analysis predicted strain and the experimentally measured strain at each strain gage location.

• 한국구조물진단유지관리공학회 논문집
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• 제22권2호
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• pp.133-140
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• 2018

본 연구에서는 중공형의 PHC말뚝과 강관말뚝을 합성한 중공형 콘크리트 충전 강관(HCFT)말뚝의 거동분석을 위한 수치해석 모델을 개발하였고 휨강도시험에 적용하여 모델의 타당성을 검증하였다. 개발된 비선형 유한요소해석 모델의 적정성을 파악하기 위해 실물 시험 결과와 비교하였고 이를 활용하여 HCFT말뚝에 적합한 접촉조건, PC강봉의 제원에 따른 효과, 콘크리트 두께에 따른 효과 등을 분석하였다. 소성응력분배법을 적용하여 HCFT말뚝의 휨강도 산정식을 제안하였고 시험 및 해석결과와 비교하여 활용성을 검증하였다. 본 연구의 결과는 HCFT말뚝의 최적설계 및 거동분석에 기초자료로 활용될 수 있을 것으로 판단된다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.521-529
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• 2019

Interlocked armor layers of unbonded flexible risers may crush when risers are being launched. In order to predict the behavior of interlocked armor layers, they are usually simplified as rings with geometric and contact nonlinearity ignored in the open-literature. However, the equivalent thickness of the interlocked armor layer has not been addressed yet. In the present paper, a geometric coefficient ${\gamma}$ is introduced to the equivalent stiffness method, and a linear relationship between ${\gamma}$ and geometric parameters of interlocked armor layers is validated by analytical and finite element models. Radial stiffness and equivalent thickness of interlocked armor layers are compared with experiments and different equivalent methods, which show that the present method has a higher accuracy. Furthermore, hoop stress distribution of interlocked armor layer under crushing is predicted, which indicates the interlocked armor layer can be divided into two compression and two expansion zones by four symmetrically distributed singular points.

• Steel and Composite Structures
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• 제42권1호
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• pp.49-57
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• 2022

This paper presents a study on the behavior of a bolted T-stub to square tube connection using Thread-fixed One-side Bolts (TOBs) through tests and numerical simulations. It outlines a research work of four connections with focus on the failure modes and strengths of the connection under tensile load. It was observed that the thread anchor failure caused by shear failure of hole threads controlled the final failure of the connection in the tests. Meanwhile, the out-of-plane deformation of tube wall resulted in the contact separation between hole threads and bolt threads, which in turn reduced the shear strength of hole threads. Finite element models (FEMs) allowing for the configuration details of the TOBs fixed connection are then developed and compared with the test results. Subsequently, the failure mechanism of hole threads and stress distribution of each component are analyzed based on FEM results. It was concluded that the ultimate strength of connection was not only concerned with the shear strength of hole threads, but also was influenced by the plastic out-of-plane deformation of tube wall. These studies lay a foundation for the establishment of suitable design methods of this type of connection.

• 농업과학연구
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• 제39권1호
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• pp.97-110
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• 2012

This study was carried out for safety evaluation, the practical application and improvement of design method of the agricultural reservoir embankment according to backside extension. Seepage analysis, slope stability analysis and finite element analysis were performed for steady state and transient conditions. Also, the pore water pressure, seepage quantity, safety factor and stress-strain behavior according to high water level and rapid drawdown were compared and analyzed. The pore water pressure at contact region between backside extension and old embankment was kept high after rapid drawdown. Therefore, backside extension is recommended that design method is required to be improved and reinforced more than the others raising embankment. The hydraulic gradients before and after backside extension showed high value at the base of the core, but they showed stable state at the upstream slope and downstream slope. The seepage quantity per 1 day and the leakage per 100 m for the steady state and transient conditions appeared to be safe against the piping. The safety factor of slope stability showed high at the steady state, and transient conditions did not show differences depending on the rapid drawdown. The safety factor was appeared high at the upstream slope before backside extension and downstream slope after extension. The excess pore water pressure for steady state and transient conditions showed negative(-) at the upstream slope, it was small at the downstream slope. The mean effective stress (p') showed high at the base of the core and to be wild distribution after the extension. The displacement after extension showed 0.02-0.06 m in the upstream slope, the maximum shear strain after extension was smaller than that before extension.

• The Journal of Advanced Prosthodontics
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• 제5권3호
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• pp.312-318
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• 2013

PURPOSE. The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS. A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ${\alpha}$=.05. RESULTS. The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 ${\mu}m/m$ at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION. Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.59-63
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• 2016

The superconducting NMR magnets have used cryogen such as liquid helium for their cooling. The conduction cooling method using cryocoolers, however, makes the cryogenic cooling system for NMR magnets more compact and user-friendly than the cryogen cooling method. This paper describes the thermal and structural analysis of a cryogenic conduction cooling system for a 400 MHz HTS NMR magnet, focusing on the magnet assembly. The highly thermo-conductive cooling plates between HTS double pancake coils are used to transfer the heat generated in coils, namely Joule heating at lap splice joints, to thermal link blocks and finally the cryocooler. The conduction cooling structure of the HTS magnet assembly preliminarily designed is verified by thermal and structural analysis. The orthotropic thermal properties of the HTS coil, thermal contact resistance and radiation heat load are considered in the thermal analysis. The thermal analysis confirms the uniform temperature distribution for the present thermal design of the NMR magnet within 0.2 K. The mechanical stress and the displacement by the electromagnetic force and the thermal contraction are checked to verify structural stability. The structural analysis indicates that the mechanical stress on each component of the magnet is less than its material yield strength and the displacement is acceptable in comparison with the magnet dimension.

• 한국재난정보학회 논문집
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• 제7권3호
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• pp.206-219
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• 2011

포장 설계기준에서 중요한 요인은 응력과 변형률 분포도이다. 합리적인 응력과 변형률 분포도를 달성하기 위한 차량타이어의 접촉면적과 공기압은 매우중요하다. 본 연구에서는 이동하중 하에서 연성포장의 점탄성 특성에 관한 내용을 다루고 있으며 현장 측정시험을 통하여 실제 도로의 종횡변형률을 수치해석 결과와 비교분석 하였다. 포장거동에 대한 차량이동하중의 영향을 적절히 모사하기 위하여 단계하중을 이용한 3차원 유한요소 해석이 수행되었다. 점탄성 해석을 위하여 아스팔트 혼합물의 이완계수, E(t), 가 실험실에서 제작된 시료의 실험으로부터 측정되었다. 현장조사 결과에 의하면, 종횡변형률은 서로 상이한 값을 보였으며 전반적으로 변형률의 크기는 차량의 속도가 증가함에 따라 감소함을 보였다. 전반적으로 횡방향 변형률은 종방향 변형률에 비하여 작은값을 보였으며 그 차이는 횡방향에서 더욱 두드러진 경향을 보였다.

• 구강회복응용과학지
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• 제34권4호
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• pp.297-305
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• 2018

목적: 다양한 형태의 공동 설계 및 재료를 이용한 하악 대구치의 치아 구조 및 intracoronal 수복물에서 발생하는 응력 분포 및 최대 von Mises 응력을 분석하고자 하였다. 연구 재료 및 방법: 콤포지트레진 및 금으로 수복한 통상적 교합면 와동과(OR-C, OG-C) 인접면 와동(MR-C, MG-C) 및 콤포지트레진으로 충전한 최소 침습적 와동을 갖는 교합면 와동(OR-M) 및 인접면 와동(MR-M)의 형상을 하악 삼차원 입체 모델로 설계했다. 저작력을 부여하기 위해 총 교합력 200 N의 정적 축 방향 하중을 10개의 교합 접촉점에서 치아에 적용했다. 유한 요소 해석은 교합 하중에 의해 생성 된 응력 분포를 예측하기 위해 수행되었다. 결과: 최소 침습적 설계를 가진 수복물은 통상적 와동 설계(341.9 MPa - 397.2 MPa)에 비해 von Mises 응력(OR-M 모델: 26.8 MPa, MR-M 모델: 72.7 MPa)의 값이 현저하게 낮았다. 치아 내부에서 최대 von Mises 응력의 크기는 통상적 와동 설계(372.8 - 412.9 MPa) 및 최소 와동 설계(361.1 - 384.4 MPa) 모델에서 유사했다. 결론: 최소 침습성 모델은 수복물 중에서 최소의 von Mises 응력이 생성되었다. 법랑질 내에서는 최대 von Mises 응력이 최소 공동 설계와 기존 설계의 모델에서 유사한 크기로 관찰되었다.

• 한국재난정보학회 논문집
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• 제15권4호
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• pp.524-530
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• 2019

연구목적: 본 논문에서는 3차원 해석프로그램을 활용하여 인터페이스 요소를 구성하고, 일반적인 부재의 특성치와 강도가 보강된 부재의 특성치 등의 실제 표현할 수 있는 물성조건을 적용하여 연결체의 복합거동 안정성을 평가하고자 하였다. 연구방법: 해석 모델은 비선형적인 재료 거동을 포함한 솔리드 요소(Solid Element)를 사용하여 빔 구조 및 원형 플랜지, 볼팅 시스템 등의 부재를 설계도면과 동일한 치수로 모델링을 완성하였고 각 부재는 하나의 복합거동연결체로 조립되는 과정에서 다른 요소유형(Element Type) 접촉면의 통일성과 매쉬(Mesh) 생성을 보다 효율적으로 제어하여 분할작업(Partition)을 수행하였으며 부재들에 활용된 강재는 Gr. 50 탄소강 재질로 모델링 하였다. 연구결과: 부재별 접촉 인접부위, 하중재하부위, 고정단 부위, 취약예상부위 등으로 하여 하중단계별 변위 및 변형, 응력상태 등을 나타내고, 유한요소 해석 후 복합거동연결체의 각 하중단계에서의 변위, 변형, 응력 등의 분포도로 영향을 검증하고 설계의 타당성을 확인하였다. 결론: 따라서 이 결과를 토대로 하여 마이크로 파일의 설계 지지력이 결정되면 복합거동 연결체의 취약 지점의 파악과 보강의 정도를 파악할 수 있을 것으로 판단된다.