• Title/Summary/Keyword: Wall deflection

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Probabilistic failure analysis of underground flexible pipes

  • Tee, Kong Fah;Khan, Lutfor Rahman;Chen, Hua-Peng
    • Structural Engineering and Mechanics
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    • v.47 no.2
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    • pp.167-183
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    • 2013
  • Methods for estimating structural reliability using probability ideas are well established. When the residual ultimate strength of a buried pipeline is exceeded the limit, breakage becomes imminent and the overall reliability of the pipe distribution network is reduced. This paper is concerned with estimating structural failure of underground flexible pipes due to corrosion induced excessive deflection, buckling, wall thrust and bending stress subject to externally applied loading. With changes of pipe wall thickness due to corrosion, the moment of inertia and the cross-sectional area of pipe wall are directly changed with time. Consequently, the chance of survival or the reliability of the pipe material is decreased over time. One numerical example has been presented for a buried steel pipe to predict the probability of failure using Hasofer-Lind and Rackwitz-Fiessler algorithm and Monte Carlo simulation. Then the parametric study and sensitivity analysis have been conducted on the reliability of pipeline with different influencing factors, e.g. pipe thickness, diameter, backfill height etc.

Tool Deflection and Geometric Accuracy to the Change of Inclination Position Angle during Machining Sculptured Surface (곡면가공시 경사위치각 변화에 따른 공구변형과 형상정밀도)

  • 왕덕현;박희철
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.4
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    • pp.55-64
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    • 2001
  • In this study, hemisphere and cylindrical shapes were machined for different tool paths and machining conditions with ball endmill cutters. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting is obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. Roundness values were found in least roundness error when down-milling in upward cutting. It is obtained the very little difference between 90。and 45。 of inclination position angle. The best surface roughness value was obtained in upward up-milling and showed different tendency with tool deflection and cutting force. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. Therefore, this phenomenon which is received over cutting resistance can be caused of chatter.

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The elastic deflection and ultimate bearing capacity of cracked eccentric thin-walled columns

  • Zhou, L.;Huang, Y.
    • Structural Engineering and Mechanics
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    • v.19 no.4
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    • pp.401-411
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    • 2005
  • The influence of cracks on the elastic deflection and ultimate bearing capacity of eccentric thin-walled columns with both ends pinned was studied in this paper. First, a method was developed and applied to determine the elastic deflection of the eccentric thin-walled columns containing some model-I cracks. A trigonometric series solution of the elastic deflection equation was obtained by the Rayleigh-Ritz energy method. Compared with the solution presented in Okamura (1981), this solution meets the needs of compatibility of deformation and is useful for thin-walled columns. Second, a two-criteria approach to determine the stability factor ${\varphi}$ has been suggested and its analytical formula has been derived. Finally, as an example, box columns with a center through-wall crack were analyzed and calculated. The effects of cracks on both the maximum deflection and the stability coefficient ${\varphi}$ for various crack lengths or eccentricities were illustrated and discussed. The analytical and numerical results of tests on the columns show that the deflection increment caused by the cracks increases with increased crack length or eccentricity, and the critical transition crack length from yielding failure to fracture failure ${\xi}_c$ is found to decrease with an increase of the slenderness ratio or eccentricity.

Deformation Behavior and Slope Stability Effect of Anchored Retention Walls Installed in Cut Slope (절개사면에 설치된 앵커지지 합벽의 변형거동 및 사면안정효과)

  • Hong Won-Pyo;Han Jung-Geun
    • Journal of the Korean Geotechnical Society
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    • v.20 no.9
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    • pp.57-64
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    • 2004
  • In order to establish the design method of anchored retention walls in cut slope, the behavior of anchored retention walls and backside ground needs to be investigated and checked in detail. In this study, the behavior of anchored retention walls was investigated by instrumentation installed in cut slope for an apartment construction site stabilized by a row of piles and anchored retention walls. When the anchor was installed at each excavating stages, the horizontal deflection of retention wall decreased, while the horizontal deformation of backside ground increased. The deflection of anchored retention wall decreased as the anchor was prestressed. The prestressed anchor farce has a great effect on the deflection of retention walls, while it has little effect on the deformation of its backside ground. The maximum horizontal deflection of anchored retention walls was developed between $1\%\;and\;4\%$ of excavation depth, which are $2\~8$ times larger than max. horizontal deflection of anchored retention walls including rock layers with backside horizontal ground. Meanwhile, SLOPILE (ver. 3.0) program analyzes the slope stability effects for anchored retention walls. As a result of analysis on slope stability analysis, the lateral earth pressure applied at anchored retention piles could be used as the mean values of empirical lateral pressures using anchored retention wall with horizontal ground at its backside.

Effects of Molding Conditions on the Deflection of Rib Moldings of Fiber-reinforced Plastic Composites in Compression Molding (섬유강화 플라스틱 복합재료의 압축성형에서 리브 성형품의 휨에 미치는 성형조건의 영향)

  • Kim, Jin-Woo;Lee, Jung-Hoon;Lee, Dong-Gi
    • Journal of Advanced Engineering and Technology
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    • v.10 no.3
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    • pp.285-290
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    • 2017
  • Molding of body with ribs is the most difficult during flow molding process. The rib area is easy to be deformed at the rear side due to wall thickness variation. In this study, relationships between molding condition and deflection of rib-shaped part is investigated during the compression molding of fiber reinforced plastic composites, and the following results are derived. Polypropylene(PP), Polystyrene(PS), and stampable sheet(SS 40wt%) show the increment of deflection along with releasing temperature. For the correlation between incremental holding pressure load and deflection, stampable sheet exhibits lower deflection along with higher holding pressure, while PS shows significant increase of deflection with higher holding pressure, PP shows completely different characteristic, significant reduction of deflection along with higher holding pressure. Regarding to mold temperature and deflection, deflection amount of SS is the biggest, and PS shows the smallest. In addition, all three kinds shows the highest amount of deflection at 173C. Deflection is reduced when mold closing speed is increased. Amount of deflection in SS is larger and is not highly dependent on molding conditions like holding pressure and cooling parameters, compared with single component material like PP. This can be elucidated by anisotropic and inhomogeneous characteristics of glass fiber during filling process of stampable sheet composite.

Finite Element Analysis of Earth Retention System with Prestressed Wales (프리스트레스트 띠장을 적용한 흙막이 시스템의 유한요소해석)

  • Park, Jong-Sik;Kim, Sung-Kyu;Joo, Yong-Sun;Kim, Nak-Kyung
    • Journal of the Korean Geotechnical Society
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    • v.24 no.3
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    • pp.25-34
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    • 2008
  • A finite element analysis was performed for new earth retention system with prestressed wales. A 3D finite element model was adopted in this study to investigate the behavior of the earth retention system with prestressed wales. A procedure of the 3D finite element modeling of this earth retention system was presented. The procedure included the modeling of soil, wall, strut, and members of prestressed wale system which consists of wale, support leg, and steel wires, and the interface modeling of soil-wall and wall-wale. The numerical predictions of lateral wall deflection, and axial load on the members of prestressed wale systems and struts were evaluated in comparison with the measurements obtained from field instruments. A sensitivity analysis was performed using the proposed 3D finite element model to investigate the behavior of new earth retention system on a wide range of prestress load conditions of steel wires. The lateral deflection of the wall and wale, the bending moment of the wale, and the lateral earth pressure distribution on the wall were computed. Implications of the results from this study were discussed.

A Study on the Behavior of Diaphragm Walls by Numerieal Method (수치해석(數値解析)에 의한 지중연속벽(地中連續壁)의 거동(擧動)에 관한 연구(硏究))

  • Lee, Hyung Soo;Chung, Hyung Sik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.10 no.4
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    • pp.123-132
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    • 1990
  • This paper deals with the influences on the wall movements and earth pressure distribution for strutted diaphragm wall of various design depth ration and pre-displacement at strutted point. The numerical method is adopted for the study. The conclusions derived from the study were summarized as followes: 1. The elasto-plastic depth ratio in the passive region is found to decrease as such parameters as wall stiffness, soil density and penetration depth ratio decrease. 2. Values of maxium bending moments of the walls decrease with the increase of soil density, and the influence to the wall stiffness increases in proportion to the penetration depth. 3. Maximum strut reaction is found to be inversely proportional to the soil density. 4. Pre-displacement at the point of strut installation must be brougt into consideration on account of its active influence to the deflection of wall bodies.

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Mass Movement of Tieback Walls (앵커의 위치에 따른 토류벽의 Mass 변형특성)

  • 김낙경;박종식;주준환
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.537-544
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    • 2003
  • Mass movement of anchored walls is defined and its characteristics were discussed. A beam on elasto-plastic foundation modeling of soldier pile and woodlagging tieback walls or anchored walls was developed and used in practice. However, the behavior of an anchored wall can not be predicted well, if the locations of anchor bonded zone are near the wall. Mass movement is defined as the movement of anchor bonded zone due to the excavation without the change in the anchor load. Case histories of anchored walls were analyzed and the normalized mass movement chart were developed. This mass movement chart can provide the idea how to locate anchors to minimize the deflection of the wall. The further the anchor bonded zone is located from the wall, the less the movement of the wall due to excavation occurs.

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A Study on Reinforcement Effect of Face Wall with Opening using Spiral Anchor (나선형철물을 사용한 치장벽체 개구부 보강 효과에 관한 연구)

  • Jung, Won-Chul;Hwang, Wan-Seon;Kwon, Ki-Hyuk
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.37-40
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    • 2007
  • Although masonry buildings fell into disfavour in the 1990's because of factors such ac bricklayers' high labor costs, bad reputation of poorly constructed masonry, masonry face wall is still preferred in korea as well as in other countries for its decorative value. Recently may problems with masonry face wall with opening have been reported, including cracks, deflection, swelling and even wall collapse in old masonry buildings, that mainly induced from the corrosion of connecting materials. So, it is necessary to develop the effective and uncorrosion connector. Therefore, this study aims to investigate the structural performance of masonry face walls with opening constructed by new connectors, spiral stainless anchors and to provide basic data for the field application of this method. The specimen reinforced bed joint has maximum load and displacement any other specimens.

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Limiting Height Evaluation for Cold-Formed Steel Wall Panels (냉간성형강재 벽체 패널의 한계높이 산정)

  • Lee, Young ki;Miller, Thomas H.
    • Journal of Korean Society of Steel Construction
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    • v.15 no.1
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    • pp.17-24
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    • 2003
  • This study aimed to develop experiment-based limiting heights for interior, nonload-bearing, cold-formed steelwall panels sheathed with gypsum board and subjected to uniformly distributed lateral loadings. Th e limiting heightswere evaluated by their strength (for flexure, shear, and web crippling) and deflection. Limiting heights for deflectionlimits of L/360, L/240, and L/120 (where L is the height of the wall) were developed over the range of typical designpressures.