• Title, Summary, Keyword: Strut effect

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Effect of Effective Compressive Strength of Concrete Strut on Structural Concrete Design (콘크리트 스트럿의 유효강도가 콘크리트 부재의 설계에 미치는 영향)

  • 윤영묵;석철호
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.241-246
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    • 2000
  • In the strut-tie model design of structural concrete, the importance of the effective strength of concrete strut has been overlooked by many practitioners. The authors believe that the effective strength of concrete strut is an important factor not only in determining steel tie forces but also in verifying the nodal zone strength and geometric compatibility condition of a selected strut-tie model. This study evaluate the effect of the effective strength of concrete strut on structural concrete design by applying the different effective strut strengths to the strut-tie model design of a post-tensioned anchorage zone and a continuous concrete deep beam.

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The Effect of Bearing Strut on the Performance of the Inducer (베어링 지지부가 터보펌프용 인듀서의 성능에 미치는 영향)

  • Choi, Chang-Ho;Noh, Jun-Gu;Kim, Jin-Sun;Hong, Soon-Sam;Kim, Jin-Han
    • 유체기계공업학회:학술대회논문집
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    • pp.519-522
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    • 2006
  • Experimental and computational studies on an turbopump inducer with and without a bearing strut were performed to evaluate the effects of a strut on the performance of an inducer. Global performance data such as head rise and efficiency, and detailed flow characteristics such as surface static pressures were measured and compared with computational results. Generally a good agreement is observed between experimental and computational results, but some discrepancies are observed due to complex flow features such as backflows at the inlet and strut/inducer interactions. For the flow rates where the backflow region is large, installing a strut enhanced the hydraulic performance of the inducer by diminishing the size of the backflows. The results also show that the strut has negligible effect on the suction performance of the inducer.

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Validity Evaluation of Determination Methods of Effective Concrete Strut Strength (콘크리트 스트럿 유효강도 결정방법의 적합성 평가)

  • 윤영묵
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.595-599
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    • 2003
  • For implementation of the strut-tie model approach to the practical analysis and design of structural concrete, the effective strengths of concrete struts in a strut-tie model, which have a crucial effect on the determination of strut and tie forces and the validity verification of strut-tie model's geometric compatibility condition, have to be determined accurately. In this study, the validity of the methods for determining the effective strengths of concrete struts was evaluated by conducting the strut-tie model analyses of the three reinforced concrete deep beams tested to failure with the effective strengths of concrete struts obtained from the suggested determination methods.

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Noise Prediction of Ducted Fan Unmanned Aerial Vehicles considering Strut Effect in Hover

  • Park, Minjun;Jang, Jisung;Lee, Duckjoo
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.144-153
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    • 2017
  • In recent years, unmanned aerial vehicles (UAVs) have been developed and studied for various applications, including drone deliveries, broadcasting, scouting, crop dusting, and firefighting. To enable the wide use of UAVs, their exact aeroacoustic characteristics must be assessed. In this study, a noise prediction method for a ducted fan UAV with complicated geometry was developed. In general, calculation efficiency is increased by simulating a ducted fan UAV without the struts that fix the fuselage to the ducts. However, numerical predictions of noise and aerodynamics differ according to whether struts are present. In terms of aerodynamic performance, the total thrust with and without struts is similar owing to the tendency of the thrust of a blade to offset the drag of the struts. However, in aeroacoustic simulations, the strut effect should be considered in order to predict the UAV's noise because noise from the blades can be changed by the strut effect. Modelling of the strut effect revealed that the dominant tonal noises were closely correlated with the blade passage frequency of the experimental results. Based on the successful detection of noise sources from a ducted fan UAV system, using the proposed noise contribution contour, methods for noise reduction can be suggested by comparing numerical results with measured noise profiles.

A Numerical Study on Strut-Placed Supersonic Flow in Annulus Flowfield (스트럿트가 있는 초음속 환형유동장에 대한 수치적 연구)

  • Park Hee Jun;Joo Won Goo
    • 한국전산유체공학회:학술대회논문집
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    • pp.53-63
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    • 2002
  • In this numerical approach, strut-placed supersonic annular flow is examined. The geometrical variations of strut cause strong influence on flowfield structures. The geometrical variations are as follows, swept effect, attack angle effect, variation of leading edge shape. These changed features such as velocity structure, pressure structure, shock-boundary layer interaction are compared and analyzed according to each geometrical configuration.

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Strut-tie model evaluation of behavior and strength of pre-tensioned concrete deep beams

  • Yun, Young Mook
    • Computers and Concrete
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    • v.2 no.4
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    • pp.267-291
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    • 2005
  • To date, many studies have been conducted for the analysis and design of reinforced concrete members with disturbed regions. However, prestressed concrete deep beams have not been the subject of many investigations. This paper presents an evaluation of the behavior and strength of three pre-tensioned concrete deep beams failed by shear and bond slip of prestressing strands using a nonlinear strut-tie model approach. In this approach, effective prestressing forces represented by equivalent external loads are gradually introduced along strand's transfer length in the nearest strut-tie model joints, the friction at the interface of main diagonal shear cracks is modeled by the aggregate interlock struts along the direction of the cracks in strut-tie model, and an algorithm considering the effect of bond slip of prestressing strands in the strut-tie model analysis and design of pre-tensioned concrete members is implemented. Through the strut-tie model analysis of pre-tensioned concrete deep beams, the nonlinear strut-tie model approach proved to present effective solutions for predicting the essential aspects of the behavior and strength of pre-tensioned concrete deep beams. The nonlinear strut-tie model approach is capable of predicting the strength and failure modes of pre-tensioned concrete deep beams including the anchorage failure of prestressing strands and, accordingly, can be employed in the practical and precise design of pre-tensioned concrete deep beams.

CFD Analysis of External Balance Strut Supporting Wind Tunnel Model (CFD를 이용한 풍동 시험 모델 지지대의 공력 특성 해석)

  • Kim C. W.;Park Y. M.;Lee J. Y.
    • 한국전산유체공학회:학술대회논문집
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    • pp.102-105
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    • 2003
  • The effect of the external balance strut on the wind tunnel model is investigated with simplified geometries. For this study, flat plate and elliptic wing are simulated with and without a cylinder. Pressure and wall shear stress distribution are analyzed to understand the effect of the cylinder.

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Strut-and-Tie Models for RC Flexural Members under Cyclic Loading (스트럿-타이 모텔을 이용한 RC 휨부재의 주기적 거동에 관한 연구)

  • 이수곤;홍성걸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.453-458
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    • 2001
  • This paper presents the procedure to find the hysteresis loop of RC member using a modified strut-and-tie model. The forces and displacements at critical points, that are initial yielding point, target displacement point, unloading elastic limit, and reloading point after pinching, are investigated with the strut-and-tie models. Using bond-slip relationship, the elastic behavior of tie element is determined. The plastic flow behavior after flexural yielding is expressed by changing the location of longitudinal strut. Determination of pinching effect completes the initial hysteresis loop, assuming that the behavior of the opposite direction is symmetrical form.

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Numerical Study on the Behavior of Corner Areas in Excavation Site (굴착 모서리부 거동에 대한 수치해석 연구)

  • Seok, Jeong-Woo;Hwang, Dae-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.757-764
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    • 2004
  • This paper deals with the numerical study on the displacement behavior of corner areas in an excavation site. Several corner areas always exist in the excavation site. The corner area has two free surfaces, which may become serious weak point from the viewpoint of structural stability. If the structural reinforcements are not applied adequately in corner areas, significant displacement of retaining wall could occur. What is worse, the collapse of retaining system rarely happens. In this paper, 3D numerical analyses were performed to investigate the effect of the arrangement of diagonal and normal strut. From the analysis results, it is found that the spacing between diagonal strut and normal strut should be less than 4m to avoid excessive displacement due to excavation.

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A new method for infill equivalent strut width

  • Tabeshpour, Mohammad Reza;Arasteh, Arash Mahdipour
    • Structural Engineering and Mechanics
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    • v.69 no.3
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    • pp.257-268
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    • 2019
  • Infills are as important members in structural design as beams, columns and braces. They have significant effect on structural behavior. Because of lots of variables in infills like material non-linear behavior, the interaction between frames and infill, etc., the infills performance during an earthquake is complicated, so have led designers do not consider the effect of infills in designing the structure. However, the experimental studies revealed that the infills have the remarkable effect on structure behavior. As if these effects ignored, it might occur soft-story phenomena, torsion or short-column effects on the structures. One simple and appropriate method for considering the infills effects in analyzing, is replacing the infills with diagonal compression strut with the same performance of real infill, instead of designing the whole infill. Because of too many uncertainties, codes and researchers gave many expressions that were not as the same as the others. The major intent of this paper is calculation the width of this diagonal strut, which has the most characteristics of infill. This paper by comprehensive on different parameters like the modulus of young or moment of inertia of columns presents a new formula for achieving the equivalent strut width. In fact, this new formula is extracted from about 60 FEM analyses models. It can be said that this formula is very efficient and accurate in estimating the equivalent strut width, considering the large number of effective parameters relative to similar relationships provided by other researchers. In most cases, the results are so close to the values obtained by the FEM. In this formula, the effect of out of plane buckling is neglected and this formula is used just in steel structures. Also, the thickness of infill panel, and the lateral force applied to frame are constant. In addition, this new formula is just for modeling the lateral stiffness. Obtaining the nearest response in analyzing is important to the designers, so this new formula can help them to reach more accurate response among a lot of experimental equations proposed by researchers.