• Title, Summary, Keyword: Uplift Force

Search Result 81, Processing Time 0.03 seconds

Uplift Capacity of a Plate Anchor Considering Suction Effects

  • Seo, Young-Kyo;Kim, Tae-Hyung
    • Journal of Ocean Engineering and Technology
    • /
    • v.22 no.6
    • /
    • pp.1-6
    • /
    • 2008
  • Anchors have been commonly used to as foundation systems of the structures that require the uplift resistance. Recently anchors have been used in ocean sediment for mooring systems to stabilizeoffshore structures. In the saturated clayey soil however suction developed between the soil and andchor and affects the uplift capacity of anchor. To estimate the uplift capacity of the andchor accurately, the failure mechanisms of the andchor by the uplift force should also be correctly assumed. The uplift capacity is usually expressed in terms of breakout factors with respect to embedment ratio. In this paper, a two-dimensional plane strain numerical investigation into the vertical uplift capacity of a plate andchor in a clayey soil is described. The breakout factor against their corresponding values of embedment ratio was calculated and plotted along a single curve. The modes of failure mechanism at shallow and deep andchors are also presented.

Experimental study on the method of estimating the vertical design wave force acting on a submerged dual horizontal plate

  • Kweon, Hyuck-Min;Oh, Sang-Ho;Choi, Young-Hwan
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • v.5 no.4
    • /
    • pp.569-579
    • /
    • 2013
  • A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974) that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.

Influence of Suction Force of Plate Anchor Embedded in Kaolinite (Kaolinite에 근입된 앵커에서 흡입력이 미치는 영향)

  • 이준대;이봉직
    • Journal of the Korean Society of Safety
    • /
    • v.12 no.4
    • /
    • pp.108-113
    • /
    • 1997
  • Plate anchors are primarily used in the foundation construction of earth-supported and earth-retaining structures. In order to estimate uplift capacity as well as suction force of clay, model tests were peformed with respect to various embedment depths and two different moisture contents in the prepared saturated kaolinite. Further, suction effects on the ultimate uplift capacity, at the various embedment depths of anchor, were also taken into account. Test results show that ultimate uplift capacity including suction force increases from 4.2kg at H/D=1 upto 11.6kg at H/D=5 in K1 and from 2.3kg at H/D=1 upto 7.3kg at H/D=5 in K2 respectively. The ratio of $F_s/Q_n/$ decreases along with the increases in the embedment ratio. In general, mud suction force under the ultimate uplift capacity in kaolinite decreases or becomes constant along with the increase of the embedment ratio.

  • PDF

Incorporating uplift in the analysis of shallowly embedded pipelines

  • Tian, Yinghui;Cassidy, Mark J.
    • Structural Engineering and Mechanics
    • /
    • v.40 no.1
    • /
    • pp.29-48
    • /
    • 2011
  • Under large storm loads sections of a long pipeline on the seabed can be uplifted. Numerically this loss of contact is extremely difficult to simulate, but accounting for uplift and any subsequent recontact behaviour is a critical component in pipeline on-bottom stability analysis. A simple method numerically accounting for this uplift and reattachment, while utilising efficient force-resultant models, is provided in this paper. While force-resultant models use a plasticity framework to directly relate the resultant forces on a segment of pipe to the corresponding displacement, their historical development has concentrated on precisely modelling increasing capacity with penetration. In this paper, the emphasis is placed on the description of loss of penetration during uplifting, modelled by 'strain-softening' of the force-resultant yield surface. The proposed method employs uplift and reattachment criteria to determine the pipe uplift and recontact. The pipe node is allowed to become free, and therefore, the resistance to the applied hydrodynamic loads to be redistributed along the pipeline. Without these criteria, a localised failure will be produced and the numerical program will terminate due to singular stiffness matrix. The proposed approach is verified with geotechnical centrifuge results. To further demonstrate the practicability of the proposed method, a computational example of a 1245 m long pipeline subjected to a large storm in conditions typical of offshore North-West Australia is discussed.

Evaluation of Uplift Force Acting on Foundation of Underground Structure (지하구조물 하부에 작용하는 양압력 평가)

  • Kim, Jin-Man;Han, Heui-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.11
    • /
    • pp.662-671
    • /
    • 2020
  • The uplift force acts directly on the foundation and causes a building to float to the upper ground. To examine the stability of a structure according to the uplift force, four sites (Paju, Anyang, Osan, and Gangneung) were selected, and sensors were installed on the foundations for the field tests. The rainfall characteristics were analyzed around June~September, and the changes in the water level of the adjacent river were considered. The maximum uplift force except for Gangneung did not exceed 72% of the water pressure when the groundwater level was up to the surface. On the other hand, the maximum uplift force in Osan was approximately 67%, but the reliability was slightly inferior because the difference from the average (46%) was large. The minimum uplift force was within 10% except for Anyang (~ 41%). At the Gangneung site on soft rock where the permanent drainage facility was installed before the measurement, the maximum and minimum uplift force was approximately 14% and 3.5%, respectively. Based on the measurement results, the possibility of overdesigning or underdesigning comes from the design by the hydrostatic pressure when the groundwater level is up to the surface.

Model Test for the Development of Installing Manipulator of Concrete Pile Anchor (콘크리트 파일앵커의 설치 매니퓨레이터의 개발을 위한 모형실험에 관한 연구)

  • 윤길수;김호상
    • Journal of Ocean Engineering and Technology
    • /
    • v.18 no.1
    • /
    • pp.47-52
    • /
    • 2004
  • Greater holding force of an anchor is required for maintaining the position of a larger floating structure. According to the series of model tests of pile anchors with movable fluke, the square type pile anchor, with fluke, showed more than 6 times of the uplift pulling force, compared to the same type pile anchor, without fluke. This uplift force is 100 times its weight. When the water depth is more than 40m, It is difficult to install the pile anchor. For a convenient installation method, a type of manipulator is proposed for the separation of a weight and buoyancy controller, using TRIZ.

The Parameter Study of Serviceability Review of End Track on Railway Bridge installed Concrete Slab Track (콘크리트궤도 부설 교량의 단부 사용성 검토를 위한 매개변수 연구)

  • Sung, Deok-Yong;Kim, Young-Ha;Park, Yong-Gul;Kim, Sung-Il
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.117-124
    • /
    • 2008
  • Construction of concrete slab track is trending to increase gradually in national and international for reduction in track maintenance cost and secure of ride comfort. However, in case of railway bridge installed concrete slab track, the serviceability review of end deck should be performed for reducing the maintenance cost of track. The serviceability review of track contains that the compression force which is occurred on fastener of end bridge should be smaller than the compression force causing the deformation limit of elastic pad and the uplift force which is occurred on fastener of end abutment should be smaller than initial fastening force. Therefore, this study calculated the deflection and end rotation of the railway bridge according to the span length and stiffness of railway bridge and estimated the compression force and uplift force which are occurred on the track of end bridge using the finite element method. This study indicated the several diagrams that are contained the correlation between the behaviour of the track and the behaviour of the railway bridge. As a result, to reduce the end rotation of the railway bridge is very efficient to increase the height of railway deck.

  • PDF

Study on uplift performance of stud connector in steel-concrete composite structures

  • Ju, Xiaochen;Zeng, Zhibin
    • Steel and Composite Structures
    • /
    • v.18 no.5
    • /
    • pp.1279-1290
    • /
    • 2015
  • The main role of studs, which act as connectors of the steel-concrete composite structures, is to ensure that the steel and the concrete work together as a whole. The studs in steel-concrete composite structures bear the shearing force in the majority of cases, but in certain locations, such as the mid-span of a simply supported composite beam, the studs bear axial uplift force. The previous studies mainly focused on the shearing performance of the stud by some experimental and theoretical effort. However, rare studies involved the uplift performance of studs. In this paper, the single stud uplift test on 10 composite specimens was performed. Meanwhile, based on the test, numerical analysis was introduced to simulate the concrete damage process due to the stud uplifted from concrete. The static ultimate bearing capacity, under which the stud connector was pulled out from the damaged reinforced concrete, is much larger than the cyclic ultimate bearing capacity, under which the weld joint between stud and steel plate fractured. According to the fatigue test results of 7 specimens, the fatigue S-N curve of the construction detail after minus 2 times standard deviation is $logN=24.011-9.171\;log{\Delta}{\sigma}$, the fatigue strength corresponding to $2{\times}10^6$ cycles is 85.33 MPa.

Crack Analysis of Concrete Gravity Dam subjected to Uplift Pressure using Surface Integral Method (표면적분법을 이용한 양압력이 작용하는 중력식 콘코리트 댐의 균열해석)

  • 진치섭;이영호;엄장섭;김태완
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.267-272
    • /
    • 2000
  • The modeling on uplift pressure on the foundation of a dam on which it was constructed, and on the interface between the dam and foundation is a critical aspect in the analysis of concrete gravity dams. The evaluation of stress intensity factor at the crack tip of concrete gravity dam due to uplift pressure effect by surface integral method is performed in this study. The effects of body force, overtopping pressure and water pressure on the crack-face are also considered in this study.

  • PDF

An Experimental Study on Suction Force of Plate Anchor Embedded in Bentonite (벤토나이트에 근입된 앵커의 흡입력에 관한 실험적 연구)

  • 이준대
    • Journal of the Korean Society of Safety
    • /
    • v.16 no.2
    • /
    • pp.97-102
    • /
    • 2001
  • Anchors are often used in construction of foundations such as transmission towers to resist uplifting forces. When plate anchors are embedded in soft clay, they may undergo a deformation under the pressure of sustained load. In soft saturated clays, the suction force can be a large par of the ultimate uplift capacity. This study is to present recent laboratory model test results conducted to evaluate the nature of variation of the suction force for plate anchors with shear strength and embedment ratio. The ratio of F$_{s}$Q$_{n}$ versus H/D in bentonite decreases with the increase of the embedment ratio.o.o.

  • PDF