• 제목/요약/키워드: shear cap

검색결과 78건 처리시간 0.022초

협착된 경동맥 내의 벽전단응력 및 혈관의 탄성적 거동 (Elastic Motion of the Blood Vessel and Wall Shear Stress in Carotid Artery with Stenosis)

  • 김창녕;오택열;최명진;정삼두
    • 한국정밀공학회지
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    • 제22권9호
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    • pp.179-187
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    • 2005
  • The characteristics of blood flow and the interaction between the blood vessel and blood flow play important roles in plaque cap rupture and the growth of atherosclerosis which may lead directly to a heart attack or a stroke. In this study, carotid arteries with different stenoses have been numerically simulated to investigate the wall shear stress(WSS) and the elastic motion of the vessel. Blood flow has been treated as physiological, laminar and incompressible flow. To model the shear thining behavior of the blood, the Carreau-Yasuda model has been employed but the viscoelasticity of blood has not been considered. The results show that the WSS of $severe(75\%)$ stenosis is much higher than those of $25\%\;and\;50\%$ stenosis in the region of stenosis. With the increase in the stenosis thickness, the expansion ratio of the center of the stenosis decreases while the expansion ratio of the upstream region of the stenosis increases.

철근콘크리트 깊은 보의 전단 내력에 대한 개구부 보강 효과 (Effect of Reinforcement for Web Opening on Shear Strength of Reinforced Concrete Deep Beams)

  • 이종권;최윤철;이용택
    • 한국전산구조공학회논문집
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    • 제20권6호
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    • pp.699-708
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    • 2007
  • 일반적으로 깊은 보의 개구부 보강을 할 경우 개구부 주변의 부족한 내력에 대해 수직, 수평, 대각, 혹은 혼합된 배근 형태를 사용하게 되는데, 경제성과 구조적 안전성을 고려하기 위해서는 각 배근 형태 및 방법에 따른 깊은 보의 거론 평가와 적절한 조합에 관한 연구가 절실히 필요하다. 이에 본 연구에서는 개구부 보강방법을 변수로 한 simulation 모델을 통해 수직, 수평 보강의 효과에 대해 해석적으로 검증을 한 후, 각 규준에서 제시하고 있는 개구부가 있는 깊은 보의 전단 내력식을 분석하고 해당 식을 보완하여 단순지지 1경간 및 연속 경간에 적용 가능한 전단 내력 산정식을 제안하고자 한다.

3차원 스트럿-타이 모델을 이용한 파일캡의 강도예측 (Strength Prediction of Concrete Pile Caps Using 3-D Strut-Tie Models)

  • 박정웅;윤영묵
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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    • pp.380-383
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    • 2003
  • Deep pile caps usually contain no transverse shear reinforcement and only small percentages of longitudinal reinforcement. The current design procedures including ACI 318-02 for the pile caps do not provide engineers with a clear understanding of the physical behavior of deep pile caps. In this study, the failure strengths of nine pile cap specimens tested to failure were evaluated using 3-dimensional strut-tie models. The analysis results obtained from the present study were compared with those obtained from several design methods, and the validity of the present method implementing 3-dimensional strut-tie models was examined.

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보-기등 접합부의 탄성거동을 위한 내진역량상세 (Capacity Detailing of Members to Ensure Elastic Behavior)

  • 김장훈
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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    • pp.119-126
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    • 1999
  • The objective of this task is to develop seismic design and capacity detailing recommendations for all portions of bridge piers that do not participate as primary energy dissipation elements. particular emphasis is given to the design requirements of cap beams and their connections of multi-column bridge pier bents. By prestressing the joints it is possible to ensure the joints remain elastic. Prestress enhances the bond and anchorage of the longitudinal column bars and also minimizes or avoids diagonal shear cracking in the joints.

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Comparative study on the bending of exponential and sigmoidal sandwich beams under thermal conditions

  • Aman, Garg;Mohamed-Ouejdi, Belarbi;Li, Li;Hanuman D., Chalak;Abdelouahed, Tounsi
    • Structural Engineering and Mechanics
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    • 제85권2호
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    • pp.217-231
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    • 2023
  • The bending analysis of sandwich functionally graded (FG) beams under temperature circumstances is performed in this article utilizing Navier's solution-based parabolic shear deformation theory. For the first time, a comparative study has been carried out between the exponential and sigmoidal sandwich FGM beams under thermal conditions. During this investigation, temperature-dependent material characteristics are postulated. Both symmetric and unsymmetric sandwich examples have been studied. The effect of gradation law, gradation coefficient, and thickness scheme on beam behavior has been thoroughly investigated. Three possible temperature combinations at the top and bottom surfaces of the beam are also investigated. Beams with a higher proportion of ceramic to metal are shown to be more resistant to thermal stresses than beams with a higher proportion of metal.

Impact-resistant design of RC slabs in nuclear power plant buildings

  • Li, Z.C.;Jia, P.C.;Jia, J.Y.;Wu, H.;Ma, L.L.
    • Nuclear Engineering and Technology
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    • 제54권10호
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    • pp.3745-3765
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    • 2022
  • The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20-70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

On the effect of porosity on the shear correction factors of functionally graded porous beams

  • Ben Abdallah Medjdoubi;Mohammed Sid Ahmed Houari;Mohamed Sadoun;Aicha Bessaim;Ahmed Amine Daikh;Mohamed-Ouejdi Belarbi;Abdelhak Khechai;Aman Garg;Mofareh Hassan Ghazwani
    • Coupled systems mechanics
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    • 제12권3호
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    • pp.199-220
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    • 2023
  • This article presents a new analytical model to study the effect of porosity on the shear correction factors (SCFs) of functionally graded porous beams (FGPB). For this analysis, uneven and logarithmic-uneven porosity functions are adopted to be distributed through the thickness of the FGP beams. Critical to the application of this theory is a determination of the correction factor, which appears as a coefficient in the expression for the transverse shear stress resultant; to compensate for the assumption that the shear strain is uniform through the depth of the cross-section. Using the energy equivalence principle, a general expression is derived from the static SCFs in FGPB. The resulting expression is consistent with the variationally derived results of Reissner's analysis when the latter are reduced from the two-dimensional case (plate) to the one-dimensional one (beam). A convenient algebraic form of the solution is presented and new study cases are given to illustrate the applicability of the present formulation. Numerical results are presented to illustrate the effect of the porosity distribution on the (SCFs) for various FGPBs. Further, the law of changing the mechanical properties of FG beams without porosity and the SCFare numerically validated by comparison with some available results.

Tensile capacity of mortar-filled rectangular tube with various connection details

  • Kim, Chul-Goo;Kang, Su-Min;Eom, Tae-Sung;Baek, Jang-Woon
    • Steel and Composite Structures
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    • 제44권3호
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    • pp.339-351
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    • 2022
  • A mortar-filled rectangular hollow structural section (RHS) can increase a structural section property as well as a compressive buckling capacity of a RHS member. In this study, the tensile performance of newly developed mortar-filled RHS members was experimentally evaluated with various connection details. The major test parameters were the type of end connections, the thickness of cap plates and shear plates, the use of stud bolts, and penetrating bars. The test results showed that the welded T-end connection experienced a brittle weld fracture at the welded connection, whereas the tensile performance of the T-end connection was improved by additional stud bolts inserted into the mortar within the RHS tube. For the end connection using shear plates and penetrating stud bolts, ductile behavior of the RHS tube was achieved after yielding. The penetrating bars increased load carrying capacity of the RHS. Based on the analysis of the load transfer mechanism, the current design code and test results were compared to evaluate the tensile capacity of the RHS tube according to the connection details. Design considerations for the connections of the mortar-filled RHS tubes were also recommended.

Finite element modeling of a deteriorated R.C. slab bridge: lessons learned and recommendations

  • Ho, I-Kang;Shahrooz, Bahram M.
    • Structural Engineering and Mechanics
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    • 제6권3호
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    • pp.259-274
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    • 1998
  • The test results from non-destructive and destructive field testing of a three-span deteriorated reinforced concrete slab bridge are used as a vehicle to examine the reliability of available tools for finite-element analysis of in-situ structures. Issues related to geometric modeling of members and connections, material models, and failure criteria are discussed. The results indicate that current material models and failure criteria are adequate, although lack of inelastic out-of-plane shear response in most nonlinear shell elements is a major shortcoming that needs to be resolved. With proper geometric modeling, it is possible to adequately correlate the measured global, regional, and local responses at all limit states. However, modeling of less understood mechanisms, such as slab-abutment connections, may need to be finalized through a system identification technique. In absence of the experimental data necessary for this purpose, upper and lower bounds of only global responses can be computed reliably. The studies reaffirm that success of finite-element models has to be assessed collectively with reference to all responses and not just a few global measurements.

Application of Tactile Slippage Sensation Algorithm in Robot Hand Control System

  • Yussof, Hanafiah;Jaffar, Ahmed;Zahari, Nur Ismarrubie;Ohka, Masahiro
    • 한국산업정보학회논문지
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    • 제17권4호
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    • pp.9-15
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    • 2012
  • This paper presents application of a new tactile slippage sensation algorithm in robot hand control system. The optical three-axis tactile sensor is a type of tactile sensor capable of defining normal and shear forces simultaneously. The tactile sensor is mounted on fingertip of robotic hand. Shear force distribution is used to define slippage sensation in the robot hand system. Based on tactile slippage analysis, a new control algorithm was proposed. To improve performance during object handling motions, analysis of slippage direction is conducted. The control algorithm is classified into two phases: grasp-move-release and grasp-twist motions. Detailed explanations of the control algorithm based on the existing robot arm control system are presented. The experiment is conducted using a bottle cap, and the results reveal good performance of the proposed control algorithm to accomplish the proposed object handling motions.