• Title/Summary/Keyword: Wall force

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Distribution of Wind Force Coefficients on the Single-span Arched House (아치형 단동하우스의 풍력계수 분포에 관한 연구)

  • 이석건;이현우
    • Journal of Bio-Environment Control
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    • v.1 no.1
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    • pp.28-36
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    • 1992
  • The wind pressure distributions were analyzed to provide fundamental criteria for the structural design on e single-span arched house according to the wind directions through the wind tunnel experiment. In order to investigate the wind force distributions, the variation of the wind force coefficients, the mean wind force coefficients, the drag force coefficients and the lift force coefficients were estimated by using the experimental data. The results obtained are as follows: 1. When the wind direction was normal to the wall, the maximum positive wind pressure along the height of the wall occurred approximately at two-thirds of the wall height because of the effects of boundary layer flow. 2. When the wind direction was 30$^{\circ}$ to the wall, the maximum positive wind force occurred at the windward edge of the wall. When the wind direction was parallel to the wall, the maximum negative wind force occurred at the windward edge of the wall. 3. The maximum negative wind force along the width of the roof appeared around the width ratio, 0.4, and that along the length of the roof appeared around the length ratio, 0.5. 4. According to the results of the mean wind force coefficients analysis, the maximum negative wind force occurred on the roof at the wind direction of 30$^{\circ}$. 5. The wind forces at the wind direction of 30$^{\circ}$ instead of 0$^{\circ}$ are recommended in the structural design of supports for a house. 6. To prevent partial damage of a house structure by wind forces, the local wind forces should be considered to the structural design of a house.

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Wall Tie Member Force Curve for the Construction Tower Crane (건축용 타워크레인 마스트의 횡방향 지지요소인 월타이 부재력 특성곡선)

  • Ko, Kwang IL;Oh, W.H.;Lee, E.T.
    • Journal of Korean Society of Steel Construction
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    • v.18 no.6
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    • pp.697-706
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    • 2006
  • Tower crane's wall tie is generally used for extending of mast height according to rising of lifting height. In order to get wall tie member force this problem, this study concerning wall tie is based on load data described in manual book of 290HC model. This study made the equation of wall tie member force and computer programming for calculating wall tie member force and then get ${\theta}-P$ curves(angle-wall tie force). After considering the ${\theta}-P$ curves, optimum angle range ($48.4^{\circ}{\sim}77.2^{\circ}$) about wall ties (A), (C) members was obtained. Member force of wall tie (B) was changed from tension to compression or from compression to tension at $74^{\circ}$ in service and $54^{\circ}$ in out of service. When both horizontal force($H_A$) and torsional moment ($M_D$) were varied from (+) to (-), wall tie force(A, B, C) were changed almost symmetrically about ${\theta}$-axis. Because this study was based on wall tie analysis conditions, wall tie members in symmetric and ideal geometry shape used for analizing wall tie of tower crane, it is necessary to have more careful verification in order to apply generally the results of this study.

Experimental Study on Energy Dissipation Capacities of the Viscous Damping Wall (벽식점성감쇠기의 감쇠 성능에 관한 기초적인 연구)

  • 이장석;김남식;조강표
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.246-251
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    • 2003
  • This paper presents an experimental study on the energy dissipation characteristics of viscous damping wall (VDW). VDW is consisted of a plate floating in a thin case made of steel plated filled with highly viscous silicone oil. Because VDW demonstrates both viscous damping and stiffness characteristics, the viscous resisting force can be expressed as the sum of velocity dependant viscous damping force and displacement dependant restoring force. The viscous resisting force and energy absorbing capacity can be easily adjusted by changing three factors, i.e. viscosity of the fluid, gap distance and area of the wall plates. VDW was tested using a series of harmonic (sinusoidal) displacement history having different frequency and amplitude and the force-displacement relationship was recorded. The relationship between dissipated energy with three factors and the influence of exciting frequency on resisting force were Investigated

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Behavior of a Heavy Particle in the Shear Flow Near a Flat Wall (벽 근처 전단 유동 내의 입자의 운동)

  • Jeong Jae-Dal;Cho Seong-Gee;Lee Chang-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.8 s.251
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    • pp.806-817
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    • 2006
  • The motion of a small rigid particle in the shear flow near a stationary flat wall is investigated in the context of Stokes flow. The lift force proposed by Saffman and later modified by Mclaughlin and Mei is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall. In the analysis, gravity, lift and drag acting on a small rigid particle near the wall are taken into account. Both analytical and numerical results for the terminal velocities, distances from the wall and trajectories of the particle are presented. In addition, we extended the present analysis to turbulent near-wall flow in the vicinity of the wall.

Modeling of Force Components Acting on Quay Walls During Earthquakes (지진시 중력식 안벽에 작용하는 하중성분의 모델링)

  • 김성렬;권오순;김명모
    • Journal of the Korean Geotechnical Society
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    • v.19 no.2
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    • pp.107-121
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    • 2003
  • When the seismic stability of quay walls is analyzed, the magnitudes of force components acting on quay walls during earthquakes and the phase relations among these force components must be properly evaluated. In general, force components include inertia force of the quay wall, lateral earth force, and water force. The magnitude and the phase relation of each force component vary according to the magnitude of the excess pore pressures developed in backfill soils of the quay wall. The dynamic thrust mobilized at the contact surface between the backfill soil and the wall develops as a result of the interactions among these force components. We propose a simple model to evaluate the magnitude and phase variation of the dynamic thrust on the back of the wall in terms of the excess pore pressure. The proposed model can predict the dynamic thrust by summing the magnitudes of farce components calculated from design equations for seismic pressures on the wall. The proposed model was verified by comparing its results with the results from a series of shaking table tests.

Effects of sheet and stamping process variables on side wall curl (딥 드로잉 벽면 만곡에 미치는 소재 및 가공조건의 영향)

  • 박기철;한수식;조태현;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.53-57
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    • 1998
  • In order to investigate the effects of the variables during the stamping process upon the side wall curl behavior, experiments and finite element analyses were done using a 90 degree draw-bending test. The variables considered were the die radius, the forming speed, the restraint force, the lubrication and the sheet grade. The experiments and simulation conditions were selected according to the design of experiment (DOE) approach. The effects of the restraint force, the lubrication and the forming speed were the same for both high strength and mild steels, but the effects of the die radius on the side wall curl were dependent on the magnitude of the die radius and the sheet grade. A straight side wall was observed for both high strength and mild steels when the die radius was about 2∼3 times of the sheet thickness. It was recommended that the restraint force, the forming speed and the friction be increased in order to reduce the side wall curl.

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Numerical analysis of sheet pile wall structure considering soil-structure interaction

  • Jiang, Shouyan;Du, Chengbin;Sun, Liguo
    • Geomechanics and Engineering
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    • v.16 no.3
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    • pp.309-320
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    • 2018
  • In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

A Study on the Coriolis Force Technique and the Flat Bottom Foot Using Ceramic Electric Wheel (도자기 전기물레를 이용한 코리올리힘 기법과 평저굽 융합에 관한 연구)

  • Kim, Seung-Man
    • The Journal of the Korea Contents Association
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    • v.18 no.1
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    • pp.441-451
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    • 2018
  • The main point of this study is to use the principle of Coriolis force and the sense of fingertips to scratch the surface of the wall by high-speed rotation (RPM) to push the texture of the stripe from the inside to the outer wall, and to express the beautiful, dynamic and distinctive outer wall texture that is diversified by Coriolis force (centrifugal force). This is designated as Coriolis force technique. In addition, instead of the traditional flat bottom foot onggi molding technique, a new type of flat bottom foot that uses the electric wheel to push the cylinder from inside to out to expand the outer wall and to spread the bottom of foot flatly. The purpose of this study is to create a modernized, distinctive, new interior work by fusing these techniques.

Hydrodynamic coupling distance between a falling sphere and downstream wall

  • Lin, Cheng-Chuan;Huang, Hung-Tien;Yang, Fu-Ling
    • Coupled systems mechanics
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    • v.7 no.4
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    • pp.407-420
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    • 2018
  • In solid-liquid two phase flow, the knowledge of how descending solid particles affected by the presence of downstream wall is important. This work studies at what interstitial distance the velocity of a vertically descending sphere is affected by a downstream wall as a consequence of wall-modified hydrodynamic forces through a validated dynamic model. This interstitial distance-the hydrodynamic coupling distance ${\delta}_c-is$ found to decay monotonically with the approach Stokes number St which compares the particle inertia to viscous drag characterized by the quasi-steady Stokes' drag. The scaling relation ${\delta}_c-St-1$ decays monotonically as literature below the value of St equal to 10. However, the faster diminishing rate is found above the threshold value from St=10-40. Furthermore, an empirical relation of ${\delta}_c-St$ shows dependence on the drop height which clearly indicates the non-negligible effect of unsteady hydrodynamic force components, namely the added mass force and the history force. Finally, we attempt a fitting relation which embedded the particle acceleration effect in the dependence of fitting constants on the diameter-scaled drop height.

Partition method of wall friction and interfacial drag force model for horizontal two-phase flows

  • Hibiki, Takashi;Jeong, Jae Jun
    • Nuclear Engineering and Technology
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    • v.54 no.4
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    • pp.1495-1507
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    • 2022
  • The improvement of thermal-hydraulic analysis techniques is essential to ensure the safety and reliability of nuclear power plants. The one-dimensional two-fluid model has been adopted in state-of-the-art thermal-hydraulic system codes. Current constitutive equations used in the system codes reach a mature level. Some exceptions are the partition method of wall friction in the momentum equation of the two-fluid model and the interfacial drag force model for a horizontal two-phase flow. This study is focused on deriving the partition method of wall friction in the momentum equation of the two-fluid model and modeling the interfacial drag force model for a horizontal bubbly flow. The one-dimensional momentum equation in the two-fluid model is derived from the local momentum equation. The derived one-dimensional momentum equation demonstrates that total wall friction should be apportioned to gas and liquid phases based on the phasic volume fraction, which is the same as that used in the SPACE code. The constitutive equations for the interfacial drag force are also identified. Based on the assessments, the Rassame-Hibiki correlation, Hibiki-Ishii correlation, Ishii-Zuber correlation, and Rassame-Hibiki correlation are recommended for computing the distribution parameter, interfacial area concentration, drag coefficient, and relative velocity covariance of a horizontal bubbly flow, respectively.