• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.246-252
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• 2000

The nonlinearity of a cable-stayed bridge results in the large displacement of main girder due to a long span, the large axial forces reduce the catenary action of cables and the flexural stiffness. Therefore, the static and dynamic behavior of pylon for a cable-stayed bridge plays an important role in determining its safety. This study was performed to find the behavior of pylon of cable-stayed bridge for the first-order analysis considering of axial load only and for the second-order analysis considering of lateral deflection due to axial load. The axial force and moment values of pylon were different from the results of the first-order analysis and second-order analysis according to pylon shape and cross beam stiffness when the pylon was subjected to earthquake and wind loads. In the second-order analysis, comparing the numerical values of the member forces for the dynamic analysis, types 3 and 4 (A type) were relatively more advantageons types than types 1 and 2 (H type). Considering the stability for pylon of cable-stayed bridge (whole structural system), types 3 and 4 (A type) with pre-buckling of girder were proper types than types 1 and 2 (H type) with buckling of pylon.

• 국제초고층학회논문집
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• 제5권1호
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• pp.1-12
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• 2016

The 1100 foot [335 m] tall Wilshire Grand Center tower under construction in Los Angeles illustrates many key outrigger issues. The tower has a long, narrow floor plan and slender central core. Outrigger braces at three groups of levels in the tower help provide for occupant comfort during windy conditions as well as safety during earthquakes. Because outrigger systems are outside the scope of prescriptive code provisions, Performance Based Design (PBD) using Nonlinear Response History Analysis (NRHA) demonstrated acceptability to the Los Angeles building department and its peer review panel. Buckling Restrained Brace (BRB) diagonals are used at all outrigger levels to provide stable cyclic nonlinear behavior and to limit forces generated at columns, connections and core walls. Each diagonal at the lowest set of outriggers includes four individual BRBs to provide exceptional capacities. The middle outriggers have an unusual 'X-braced Vierendeel' configuration to provide clear hotel corridors. The top outriggers are pre-loaded by jacks to address long-term differential shortening between the concrete core and concrete-filled steel perimeter box columns. The outrigger connection details are complex in order to handle large forces and deformations, but were developed with contractor input to enable practical construction.

• Composites Research
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• 제27권4호
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• pp.152-157
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• 2014

Non-destructive testing methods of composite materials are very important for improving material reliability and safety. AE measurement is based on the detection of microscopic surface movements from stress waves in a material during the fracture process. The examination of AE is a useful tool for the sensitive detection and location of active damage in polymer and composite materials. FBG (Fiber Bragg Grating) sensors have attracted much interest owing to the important advantages of optical fiber sensing. Compared to conventional electronic sensors, fiber-optical sensors are known for their high resolution and high accuracy. Furthermore, they offer important advantages such as immunity to electromagnetic interference, and electrically passive operation. In this paper, the crack detection capability of AE (Acoustic Emission) measurement was compared with that of an FBG sensor under tensile testing and buckling test of composite materials. The AE signals of the PVDF sensor were measured and an AE signal analyzer, which had a low pass filter and a resonance filter, was designed and fabricated. Also, the wavelength variation of the FBG sensor was measured and its strain was calculated. Calculated strains were compared with those determined by finite element analysis.

• Steel and Composite Structures
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• 제33권6호
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• pp.877-889
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• 2019

The developments of double skin composite (DSC) walls with novel enhanced C-channel connectors (DSCW-EC) were reported. Followed axial compression tests on prototype walls were carried to evaluate structural performances of this novel DSC composite structures. The testing program consists of five specimens and focused on the layout of the novel enhanced C-channel (EC) connectors, which include the web direction of C-channels, steel-faceplate thickness, vertical and horizontal spacing of C-channels. Crushing in concrete core and buckling of steel faceplate were two main observed failed modes from the compression tests. However, elastic or plastic buckling of the steel faceplate varies with designed parameters in different specimens. The influences of those investigated parameters on axial compressive behaviors of DSCW-ECs were analyzed and discussed. Recommendations on the layout of novel EC connectors were then given based on these test results and discussions. This paper also developed analytical models for predictions on ultimate compressive resistance of DSCW-ECs. Validation against the reported test results show that the developed theoretical models predict well the ultimate compressive resistance of DSCW-ECs.

• 대한조선학회 특별논문집
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• 대한조선학회 2006년도 특별논문집
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• pp.89-96
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• 2006

The objective of this paper is to find out a reasonable method for docking analysis of ships. The characteristics of reaction force distribution under docking condition are investigated by carrying out parametric study. To assess the allowable reaction force on keel block from structural strength point of view, two kinds of structural assessment methods are proposed in accordance with expected collapse pattern. In order to verify the proposed method, linear buckling and elasto-plastic large deflection analyses of typical double bottom structure are carried out and the results are compared.

• 국제강구조저널
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• 제18권4호
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• pp.1397-1409
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• 2018

Stiffened plates with high slenderness parameters show large out-of-plane deflections, due to elastic buckling, which may occur before the plates reach their ultimate strength. From a serviceability point of view, restriction of out-of-plane deflections exceeding the fabrication tolerance is of primary importance. Compressive strength at the serviceability limit state (SLS) for slender stiffened plates under uniaxial stress was investigated through nonlinear elasto-plastic finite element analysis, considering both geometric and material nonlinearity. Both normal and high-performance steel were considered in the study. The SLS was defined based on a deflection limit and an elastic buckling strength. Probabilistic distributions of the SLS strengths were obtained through Monte Carlo simulations, in association with the response surface method. On the basis of the obtained statistical distributions, partial safety factors were proposed for SLS. Comparisons with the ultimate strength of different design codes e.g. Japanese Code, AASHTO, and Canadian Code indicate that AASHTO and Canadian Code provide significantly conservative design, while Japanese Code matches well with a 5% non-exceedance probability for compressive strength at SLS.

• Steel and Composite Structures
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• 제43권1호
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• pp.67-77
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• 2022

In the current study, ordinary design of Represstessed Pre-Flex (RPF) girder by classical beam theory and numerical model taking buckled shape into consideration were compared with field-survey data to find imperfections on the RPF girder before prestressing and after preflexion. It should be noted that the ordinary design do not consider deformed shape of steel girder in RPF beam. The deformed shapes of steel girder due to the incomplete fabrication that could be caused by self-weight, preflexion misalignment, existence of lateral bracing at mid-span and stiffness of reaction frame were found using a newly developed model which was verified against a deformation survey conducted on actual RPF girder in the field. The final observed deformed shapes of RPF after concrete shrinkage and before prestressing were classified into W, C and Unsymmetric shapes in regard to both survey and analytical results. The deformation survey showed negligible amount of unwanted deformation compared to the large size of the RPF girders. The shallower width of the bottom flange of steel girder caused amount of lateral torsional buckling under self-weight and preflexion thereby affecting the unwanted final overall shape of the RPF girders. However, it was found that the unwanted deformation of RPF girders by fabrication errors even though it is negligible compared to the size of the girder, caused unsymmetrical stress contours in concrete and additional tensile stress and raise some safety issues.

• 생물환경조절학회지
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• 제17권3호
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• pp.181-187
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• 2008

유한요소해석 코드인 ANSYS를 이용, 폭 5.6m간이 느타리재배사를 3차원 강뼈대 구조물로 모델링하여 베드기둥 형태 및 파이프 규격에 따른 구조적 안전성을 분석하였으며 허용응력 설계법에 기초해 구조안전 여부를 판단하였다. 전산구조 해석 결과, 베드기둥에 따른 구조적 안전성은 안전적설심의 경우, 직립형 베드기둥 구조가 다른 베드기둥 형태보다 훨씬 높게 나타났으나 안전풍속 측면에서는 형태별 차이가 없는 것으로 나타났다. 서까래 규격과 베드기둥 설치 간격에 따른 구조적 안전성은 본 연구에서 고려한 파이프 규격 범위에 있어서 안전풍속 측면의 경우, 베드기둥 설치간격보다 시설 외부적 요소인 서까래 간격에 더 영향을 받는 것으로 나타났으나 안전적설심 측면에서는 안전 풍속과는 반대로 서까래 간격보다는 시설 내부적 구조물인 베드기둥 간격이 더 중요한 것으로 나타났다. 베드기둥의 좌굴에 대한 안전성은 해석의 모든 경우에서 안전한 것으로 나타났다.

• 해양환경안전학회지
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• 제10권2호
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• pp.41-47
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• 2004

선체구조 부재에는 이중저의 거더 및 늑판등에서 유공을 가진 판이 많이 사용되고 있는데, 이는 중량 경감, 사람 및 화물의 이동, 배관 등의 목적이다. 보통은 강도상 큰 문제가 없는 부위에 위치하지만, 매로는 불가피하게 높은 응력이 작용하는 부위에 설치해야 할 경우가 있다. 이러한 판에 유공의 존재는 면내 하중에 의한 탄성좌굴강도 및 최종강도에 큰 영향을 주게 된다. 따라서, 유공판의 탄성좌굴강도 및 최종강도 평가는 선박의 초기 구조설계단계에서 구조부재 치수를 결정할 매, 검토해야 할 중요한 설계기준 중의 한가지가 된다. 그러므로, 유공판에 대한 합리적이고 신뢰적인 탄성좌굴강도 및 최종강도 설계식이 필요하게 되었다. 본 연구에서는 다양한 종횡비와 유공의 치수비 그리고 세장비의 영향을 고려하여 탄소성대변형 유한요소법을 근간으로 한 해석코드인 ANSYS(7.1)를 사용하여 시리즈해석을 수행하였다.

• 한국강구조학회 논문집
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• 제28권3호
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• pp.185-194
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• 2016

본 연구에서는 탄소섬유쉬트로 보강된 각형강관 기둥의 유한요소 해석결과를 소개하고 있다. 실험체 개수는 총 6개이며, 각형강관에 대해서는 비조밀 단면 단주, 세장판 단면 단주, 비조밀 단면 장주로 구성되어 있다. 실험변수는 탄소섬유쉬트 보강겹수이다. AFRP 스트립과 강재사이의 부착거동과 부착응력-슬립관계를 규명하였다. 총 6개의 실험체에 대하여 ANSYS V.14.0을 사용하여 유한요소해석을 수행하였으며, 파괴모드, 하중-변위곡선, 최대내력, 초기강성에 대해 실험결과와 비교하였다. 끝으로, AISC cold-formed steel structures 기준에 근거하여 세장비에 따른 좌굴응력값을 산정하였으며, 각 단면타입에 대한 좌굴응력값 및 보강효과를 비교하였다.