• 제목/요약/키워드: global bending

검색결과 141건 처리시간 0.024초

Plastic load bearing capacity of multispan composite highway bridges with longitudinally stiffened webs

  • Unterweger, Harald;Lechner, Andreas;Greiner, Richard
    • Steel and Composite Structures
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    • 제11권1호
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    • pp.1-19
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    • 2011
  • The introduction of the Eurocodes makes plastic design criteria available also for composite bridges, leading to more economical solutions compared with previous elastic design rules. Particularly for refurbishment old bridges with higher actual traffic loads, up to date outside the scope of the Eurocodes, strengthening should therefore be avoidable or at least be necessary only to a minor extent. For bridges with smaller spans and compact cross sections, the plastic load bearing capacity is clearly justified. In this work, however, the focus is placed on long span continuous composite bridges with deep, longitudinally stiffened girders, susceptible to local buckling. In a first step, the elastic - plastic cross section capacity of the main girder in bending is studied as an isolated case, based on high preloads acting on the steel girder only, due to the common assembling procedure without scaffolding. In a second step, the effects on the whole structure are studied, because utilising the plastic section capacity at midspan leads to a redistribution of internal forces to the supports. Based on the comprehensive study of an old, actual strengthened composite bridge, some limitations for plastic design are identified. Moreover, fully plastic design will sometimes need additional global analysis. Practical recommendations are given for design purposes.

A large scale simulation of floe-ice fractures and validation against full-scale scenario

  • Lu, Wenjun;Heyn, Hans-Martin;Lubbad, Raed;Loset, Sveinung
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제10권3호
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    • pp.393-402
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    • 2018
  • While interacting with a sloping structure, an ice floe may fracture in different patterns. For example, it can be local bending failure or global splitting failure depending on the contact properties, geometry and confinement of the ice floe. Modelling these different fracture patterns as a natural outcome of numerical simulations is rather challenging. This is mainly because the effects of crack propagation, crack branching, multi fracturing modes and eventual fragmentation within a solid material are still questions to be answered by the on-going research in the Computational Mechanic community. In order to simulate the fracturing of ice floes with arbitrary geometries and confinement; and also to simulate the fracturing events at such a large scale yet with sufficient efficiency, we propose a semi-analytical/empirical and semi-numerical approach; but with focus on the global splitting failure mode in this paper. The simulation method is validated against data we collected during the Oden Arctic Technology Research Cruise 2015 (OATRC2015). The data include: 1) camera images based on which we specify the exact geometry of ice floes before and after an impact and fracturing event; 2) IMU data based on which the global dynamic force encountered by the icebreaker is extracted for the impact event. It was found that this method presents reasonably accurate results and realistic fracturing patterns upon given ice floes.

금속재 세미 모노코크 콘형 구조체의 정적 구조 시험

  • 박순홍;장영순;이영무
    • 항공우주기술
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    • 제4권1호
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    • pp.129-142
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    • 2005
  • KSLV-I의 위성 어댑터의 구조 형식으로 결정된 세미 모노코크 형식의 잘려진 원뿔형 구조체를 제작하고, 정적 구조 시험을 수행하였다. 설계 하중에 따라 순수 압축, 순수 굽힘, 순수 전단, 복합 하중을 가하여 변형률 및 변위를 측정하고, 구조의 건전성을 확인하였다. 최종적으로 파괴 시험을 수행하여, 국부 좌굴 모드 및 파괴 형상을 관찰하였으며, 파괴하중 및 모드를 유한 요소법으로 해석하여 비교한 결과 정확한 파괴 하중의 예측이 가능하였다.

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RC 짧은보(a/d<2.5)의 순간처짐 산정에 대한 연구 (Instantaneous Deflection calculation Incorporated with Internal Force State Factor In RC short beams(a/d<2.5))

  • 오현철;정제평;김우
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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    • pp.713-718
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    • 2001
  • This paper describes an attempt to develop a new equation to calculate deflection for reinforced concrete deep beams(a/d<2.5). The main idea incorporated with this equation is the internal force state factor($\alpha$)which is able to express global state of internal force flow in cracked reinforced concrete beams subjected to shear and bending. A new equation for deflection calculation using internal force state factor($\alpha$)provides more exact result of deflection in reinforced concrete deep beams than the equation predicted by the current code provisions.

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엘보우의 붕괴모멘트에 미치는 감육결함의 영향 (Effect of Wall Thinning Defect on the Collapse Moment of Elbow)

  • 김진원;김태순;박치용
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.622-628
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    • 2003
  • The purpose of this study is to evaluate the effect of local wall thinning on the collapse of elbow subjected to internal pressure and bending moment. Thus, the nonlinear 3D finite element analyses were performed to obtained collapse moment of elbow containing various wall thinning defects under two loading; modes (closing and opening modes) and defect locations (intrados and extrados). From the results of analyses, the influence of wall thinning defect on the global moment-rotation behavior of elbow was discussed, and the dependance of collapse moment of elbow on wall thinning depth, length, and circumferential angle was investigated under different loading mode and defect location.

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유한요소해석을 이용한 국부 감육배관에 대한 응력집중계수 제시 (Finite Element Based Stress Concentration Factors for Pipes with Local Wall Thinning)

  • 손범구;김윤재;김영진
    • 대한기계학회논문집A
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    • 제28권7호
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    • pp.1014-1020
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    • 2004
  • The present work complies the elastic stress concentration factor for a pipe with local wall thinning, based on detailed three-dimensional elastic FE analysis. To cover practically interesting cases, a wide range of pipe and defect geometries are considered, and both internal pressure and global bending are considered. Resulting values of stress concentration factors are tabulated for practical use, and the effect of relevant parameters such as pipe and defect geometries on stress concentration factors are discussed. The present results would provide valuable information to estimate fatigue damage of the pipe with local wall thinning under high cycle fatigue.

온도변화에 따른 MEMS 자이로스코프 패키지의 변형측정 (Deformation Behavior of MEMS Gyroscope Package Subjected to Temparature Change)

  • 주진원;최용서;좌성훈;송기무
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.1407-1412
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    • 2003
  • In MEMS devices, packaging induced stress or stress induced structure deformation become increasing concerns since it directly affects the performance of the device. In this paper, deformation behavior of MEMS gyroscope package subjected to temparature change is investigated using high-sensitivity $Moir{\acute{e}}$ interferometry. Using the real-time $Moir{\acute{e}}$ setup, fringe patterns are recorded and analyzed at several temperatures. Temperature dependent analyses of warpages and extensions/contractions of the package are presented. Linear elastic behavior is documented in the temperature region of room temperature to $125^{\circ}C$. Analysis of the package reveals that global bending occurs due to the mismatch of thermal expansion coefficient between the chip, the molding compond and the PCB.

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전달 행렬법과 유한요소법을 이용한 중공 크랭크축의 강제 진동 해석 (Forced Vibration Analysis of a Hollow Crankshaft by using Transfer Matrix Method and Finite Element Method)

  • 김관주;최진욱
    • 한국자동차공학회논문집
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    • 제5권6호
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    • pp.44-52
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    • 1997
  • As part of the effort to reduce the weight of powertrain, a hollow crankshaft has been designed. The mass reduction of the crankshaft changes the dynamic properties of the crankshaft such as moment of inertia, and torsional, bending stiffness. The purpose of this paper is to compare the dynamic behavior of the hollow crankshaft with that of the original, solid crankshaft. Global dynamic behavior of the crankshaft is analyzed bgy the transfer matrix method(TMM). The crankshaft has been modeled by 38 lumped mass and stiffness elements. The dynamic patameters of each lumped element are provided by Finite Element Method(FEM). The responses of the crankshaft from TMM are fed back as loading conditions to the Finite Element model to obtain dynamic stresses for critical areas of the crankshaft.

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Seismic design and assessment of steel-concrete frame structures with welded dissipative fuses

  • Calado, Luis;Proenca, Jorge M.;Sio, Joao
    • Steel and Composite Structures
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    • 제35권4호
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    • pp.527-544
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    • 2020
  • This research presents the design and numerical assessment of composite steel-concrete frame structures with welded dissipative fuses. The assessment has been carried out based on linear response spectrum, nonlinear static pushover and time history procedures. The analytical expressions which define the envelope of the nonlinear response of the dissipative fuses are first presented and calibrated against experimental results available in literature. The assessment is then carried out according to a design methodology proposed herein. Outcomes of the numerical assessment indicate that the use of welded dissipative fuses successfully limited damage within the replaceable parts. Furthermore, although structures with dissipative fuses present lower strength and, generally, lower displacement capacity, their displacement ductility and global dissipative performance are generally higher than conventional structures, especially when the structure with dissipative fuses presents a dissipative configuration adjusted to the bending moment distribution diagram calculated for the applied seismic action.

카테터의 거동을 시뮬레이션 하기 위한 고정된 길이를 유지하는 실 형상의 변형체 모델 (An Inextensible Wire-shaped Deformation Model for Catheter Simulation)

  • 한혜현;이두용
    • 제어로봇시스템학회논문지
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    • 제22권8호
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    • pp.610-614
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    • 2016
  • This paper proposes an inextensible wire-shaped deformation model to simulate catheter behavior. The wire-shaped model consists of serially-connected mass points and massless rigid links. Torsional springs and dampers are employed to accommodate bending. Deformation is computed by updating the rotation angles from the global coordinates while maintaining the fixed length condition. Equations of motion is derived from double pendulum motion. Spring constant is computed using strain energy and potential energy stored in a torsional spring to reflect material property. Simulation is conducted to show deformation of wire model while maintaining inextensibility condition and including material properties. The proposed method guarantees inextensible constraint in the catheter simulation.