• Title/Summary/Keyword: width-to-depth ratio

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Effects of deck's width-to-depth ratios and turbulent flows on the aerodynamic behaviors of long-span bridges

  • Lin, Yuh-Yi;Cheng, Chii-Ming;Lan, Chao-Yuan
    • Wind and Structures
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    • v.6 no.4
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    • pp.263-278
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    • 2003
  • This study investigates the effects of a bridge deck's width-to-depth (B/H) ratio and turbulence on buffeting response and flutter critical wind speed of long-span bridges by conducting section model tests. A streamlined box section and a plate girder section, each with four B/H ratios, were tested in smooth and turbulent flows. The results show that for the box girders, the response increases with the B/H ratio, especially in the vertical direction. For the plate girders, the vertical response also increases with the B/H ratio. However, the torsional response decreases as the B/H ratio increases. Increasing the B/H ratio and intensity of turbulence tends to improve the bridge's aerodynamic stability. Experimental results obtained from the section model tests agree reasonably with the calculated results obtained from a numerical analysis.

Analysis of Types of Gather Drape with Visual Evaluation (시각적 평가에 의한 개더 드레이프 형상 분석)

  • Lee Myung-Hee;Jung Hee-Kyeong
    • Journal of the Korea Fashion and Costume Design Association
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    • v.7 no.1
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    • pp.33-40
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    • 2005
  • Gathering is method used to control fullness along a seam line. The purpose of this study was to investigate the relationship between the quantitative research and qualitative method; the effect of gather and the types of gather drape. The experimental design consists of four factors: (l) three kinds of different weight and thickness of fabrics (2) three kinds of stitch densities (3) five kinds of ratio of gathers (4) three kinds of grain directions. Therefore one hundred thirty five (135) samples were made. And utilized SPSS WIN 10.0 Package in data analysis. The results of this study were as follows; First, after frequency analysis, side height, hem line width, node depth, node count, node width accorded with these result data recording. Second, after correlation analysis, side height related with front statements. Side height and entire visual was negative correlation. Hem line width, node depth, node count with section statements was negative correlation but node width at section statements was positive correlation. Third, after $k^2$ analysis, front picture parts getting excellent evaluation were 1st side height, 3rd hem line width, 4th node depth, 3rd node count, 3rd node width. And section illustration parts getting excellent evaluation were 4th side height, 1st hem line width, 2nd node depth, 3rd node count, 4th node width.

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Determination of Effective Flange Width in Single Plane Cable-Stayed Concrete Bridge (1면 케이블 콘크리트 사장교의 유효플랜지폭 결정에 관한 연구)

  • Lee, Hwan-Woo;Kim, Kwang-Soo;Kang, Ho-Jun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.4
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    • pp.343-351
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    • 2010
  • Bending and axial compressive stresses are distributed across the whole upper flange of a box girder bridge which has the span-to-depth ratio (B/L) of below 0.5, according to Korea Bridge Design Specifications (Minister of Land, Transport and Maritime Affairs, 2005). Shear lag phenomenon, however, can take place in the construction phase of cable-stayed bridge, in which stresses combining bending moment due to dead weight and cable vertical compression are induced. This study aims to analyze the effective width of flange over which composite stresses are given, which should be calculated during the construction phase of stiffening girder of single plane cable-stayed box girder bridge. The study results indicate that the full width of stiffening girder can be regarded as the effective flange width when the span-to-depth ratio for the deck is below 0.38. In other words, the area, where shear lag is taken into consideration, is larger than the width of box girder in single plane cable-stayed box girder bridges. Therefore, the current practice of considering the full width as the effective flange width regardless of changes of the span-to-depth ratio during the construction stage can produce an unsafe bridge. If the effective flange width is determined according to the single span structural system in the early stage of construction when the span-to depth ratio for the deck is high and composite stresses of every part expect each end of the bridge are calculated, it can result in a safe structural design. Since the span-to-depth ratio gradually decreases, however, it is appropriate to determine the effective width of flange on the basis of the full width and the cantilever structural system.

Lubrication Performance Analyses of Spiral Groove Dry Gas Seals - Part II: Detailed Performance Evaluation of Groove Design Parameters (스파이럴 그루브 드라이 가스 시일의 윤활 성능해석 - Part II: 그루브 설계 파라미터의 상세 성능평가)

  • Lee An Sung;Yang Jae-Hun;Choi Dong-Hoon
    • Tribology and Lubricants
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    • v.20 no.2
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    • pp.68-76
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    • 2004
  • Applying a general Galerkin FE lubrication analysis method to spiral groove dry gas seals, this study intends to analyze in detail the effects of groove design parameters, such as a spiral angle, groove width ratio, groove radius ratio, groove depth ratio, and groove taper ratio, on the lubrication performances of an opening force, leakage, axial stiffness and damping, and angular stiffness and damping at low and high rotating speeds: 3,600 and 15,000 nm. Results show that, for the primary design consideration performances such as the opening force and axial and angular stiffnesses, a spiral angle of $25^{\circ}$, a groove width ratio of 0.46, a groove radius ratio of 1.1, a groove depth ratio of 1.0, and a groove taper ratio of 0.0 are preferred. Where the recommended relatively low values of groove depth and taper ratios are to keep the axial and angular dampings positive or higher than 0 particularly at the high rotating speed.

Numerical Analysis of Electroosmotically Enhanced Microchannel Heat Sinks (전기삼투를 이용한 미세열방출기의 수치해석)

  • Husain, Afzal;Kim, Kwang-Yong
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2544-2547
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    • 2008
  • A micro channel heat sink has been studied and optimized for mixed pressure driven and electroosmotic flows through three-dimensional numerical analysis. The effects of ionic concentration represented by zeta potential and Debye thickness are studied with the various steps of externally applied electric potential. Optimization of the micro channel heat sink has been performed considering two design variables related to the micro channel width, depth and fin width. The surrogate-based optimization is performed using a search algorithm taking overall thermal resistance as objective function. The thermal resistance is found to be more sensitive to channel width-to-depth ratio than fin width-to-depth of channel ratio.

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A Study on the GMA Welding Characteristics of Al5083-O Aluminum Alloy According to the Shield Gas Mixing Ratio and Heat Input (Al5083-O 알루미늄합금의 보호가스 혼합비율 및 입열량에 따른 GMA용접 특성에 관한 연구)

  • 정재강;양훈승;이동길
    • Journal of Welding and Joining
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    • v.20 no.2
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    • pp.65-70
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    • 2002
  • This study was to evaluate GMA welding characteristics of the A15083-O aluminum alloy according to the shield gas mixing ratio and heat input change. The GMA welding of the base metal was carried out with flour different shield gas mixing ratios(Ar100%+He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%). Regarding the if1uence on the bead shape of the shield gas mixing ratio and heat input, the bead width was greatest in Ar100%+He0% mixture. But the penetration depth and area were greatest in Ar33%+He67% mixture considering that the lower Ax gas ratio, the higher bead depth and area. Also, dilution was also best in the shield gas mixing ratio. The size and number of deflects were least in Ar33%+He67% mixture. Higher He gas ratio resulted in less deflects detected by the radiographic inspection.

A Study on the Allowable Crack Width of RC Beam with Corrosive Environment (염해환경에서의 RC보의 허용 균열폭 산정에 관한 연구)

  • Kim, Dongbaek;Kwon, Soondong;An, Kwanghee
    • Journal of the Society of Disaster Information
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    • v.11 no.2
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    • pp.253-261
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    • 2015
  • Deterioration of reinforced concrete structures in corrosive environment is tend to be accelerated due to ingress of aggressive ion such as chloride ion. Chloride-induced corrosion is affected by various factors such as cover concrete qualities, width of existing cracks, and cover depth of concrete. However, the allowable crack width of RC structure in design code does not consider the concrete material properties and conditions of construction except the cover depth. In this paper, an equation for allowable crack width is proposed to consider the cover concrete quality, crack width, and cover depth. Crack width, cover depth, and water-cement ratio of concrete are selected as influencing factors on corrosion of reinforcement for rapid chloride tests. From test results, the relationships between the factors and corrosion are derived. Finally, the equation for allowable crack width is derived in terms of concrete compressive strength and cover depth. The presented equation is verified by comparative calculations with design code variables.

Study on lateral behavior of digging well foundation with consideration of soil-foundation interaction

  • Wang, Yi;Chen, Xingchong;Zhang, Xiyin;Ding, Mingbo;Lu, Jinhua;Ma, Huajun
    • Geomechanics and Engineering
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    • v.24 no.1
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    • pp.15-28
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    • 2021
  • Digging well foundation has been widely used in railway bridges due to its good economy and reliability. In other instances, bridges with digging well foundation still have damage risks during earthquakes. However, there is still a lack of knowledge of lateral behavior of digging well foundation considering the soil-foundation interaction. In this study, scaled models of bridge pier-digging well foundation system are constructed for quasi-static test to investigate their lateral behaviors. The failure mechanism and responses of the soil-foundation-pier interaction system are analyzed. The testing results indicate that the digging foundations tend to rotate as a rigid body under cyclic lateral load. Moreover, the depth-width ratio of digging well foundation has a significant influence on the failure mode of the interaction system, especially on the distribution of foundation displacement and the failure of pier. The energy dissipation capacity of the interaction system is discussed by using index of the equivalent viscous damping ratio. The damping varies with the depth-width ratio changing. The equivalent stiffness of soil-digging well foundation-pier interaction system decreases with the increase of loading displacement in a nonlinear manner. The absolute values of the interaction system stiffness are significantly influenced by the depth-width ratio of the foundation.

The Analysis of User Preference of the Room W/D Ratio Changed by Merging Balcony to Room (아파트 실의 발코니 확장으로 인한 실의 장단변비 변화와 거주자의 선호도 조사)

  • 진경일;안병욱
    • Korean Institute of Interior Design Journal
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    • no.41
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    • pp.104-111
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    • 2003
  • Most residential buildings in Korea are preferred to have maximum interior spaces, rather than consider its original design, overall building performance, and any other aspects since early 1990's. Especially in high-rise apartment buildings, balcony has been merged to living room to get more interior spaces and this renovation trends have been producing deep and narrow shapes of living rooms that was not initially intended by architects. On the other hand, the same gross area of each unit does not necessarily mean same width and depth ratio of each residential unit. Generally, we can categorize it to the deep or wide unit based on its width and depth ratio. Under these circumstances, this study analyzes the room usage pattern changes based on the space width and depth ratio and the effect of expansion of room space to the balcony. This study also includes about 180 apartments plan case studies to find out the relationships among w/d ratio changes, furniture arrangement types, and room configurations. In this research, general apartment room w/d ratios are 0.97 ∼ 1.23; 0.7(south facing sitting room), 1.23(south facing bed room), and 0.95(north facing bedroom). But, after expanding room space to balcony w/d ratio increased as follows; sitting room become 1.31, general south facing bedroom become 1.23, and north facing bedroom become 1.45. In addition to user preference of w/d ratio, many people prefer rectangular room shape a little(w/d ratio is 0.9 or 1.2) than square style (w/d ratio is 1.0) or very deep room style (w/d ratio Is more over 1.5). Accordingly, expanding the room space to balcony may make unsatisfactory room w/d ratio. Expanding room space to balcony should be considered by existing room w/d ratio.

Experimental study on transmission and stability of submerged breakwater (잠제의 전달율과 안정성에 관한 실험적 연구)

  • Kim, Yong-Woo;Yoon, Han-Sam;Kim, Hong-Jin;Ryu, Cheong-Ro;Sohn, Byung-Kyu
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.213-219
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    • 2003
  • As the 2-D hydraulic experimental results for the submerged rubble-mound structure, we have concerned with their stability/function characteristics of structures by the effects of wave force, scour/deposition at the toe and wave transmission ratio at the lee-side sea. And as to investigate the variation characteristics of wave transmission ratio which depended to a geometrical structure of the submerged breakwater profiles, the critical conditions for the depth of submergence and crest width obviously presented. In summary, there results lead us to the conclusions that the wave control capabilities of submerged breakwaters by the variation of the submergence depth is high about 4 time degrees at the efficiency than the that of crest width. The destruction of covering block at the crest generated at the region which located between maximum damage curve, it maximum damage/failure station from the toe of the structure were 0.2L. As the wave transmission coefficient and the slope of the structure increase, the damage/failure ratio and the maximum scour depth at the toe was extended, respectively. When maximum scour depth happened. The destruction of covering block which located at the toe generated at the front slope destruction. Finally, it was found from the results that the optimization of structure may be obtained by the efficiently decision of the submergence depth and crest width in the permissible range of wave transmission ratio.

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