• Title/Summary/Keyword: bi-directional loading test

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A Numerical Analysis Study for Estimation of Ultimate Bearing Capacity and An Analysis of the High Capacity Bi-directional Pile Load Tests of the Large-diameter Drilled Shafts (대구경 현장타설말뚝의 대용량 양방향 말뚝재하시험 분석 및 극한지지력 추정을 위한 수치해석 연구)

  • Nam, Moonsuk;Kim, Sangil;Hong, Seokwoo;Hwang, Seongchun;Choi, Yongkyu
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.10
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    • pp.63-72
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    • 2011
  • The high capacity bi-directional pile load test is an optimum pile load test method for high-rised buildings. Especially, a high pressure and double-acting bi-directional pile load testing, a special type of the high capacity bi-directional pile load test, is the most practical way to overcome limitations of loading capacities and constraints of field conditions, which was judged to be a very useful test method for requiring high loading capacities. Total of 2 high capacity bi-directional pile load tests(P-1 and P-2) were conducted in high-rised building sites in Korea. Based on the field load test results, the sufficiency ratio of loading capacities to design loads for P-1 and P-2 were 3.3 and 2.1, respectively. For P-2, the load test could not verify the design load if 1-directional loads applied slightly smaller than the actual applied load. Also, high capacity bi-directional pile load tests were difficult to determine an ultimate state of ground or piles, although the loads were applied until their maximum loads. Hence, finite element analyses were conducted to determine their ultimate states by calibrating and extrapolate with test results.

Study of Smart Bi-directional Pile Load Test by Model Test (모형시험을 통한 Smart 양방향말뚝 재하시험에 관한 연구)

  • Kim, Nak-Kyung;Kim, Ung-Jin;Joo, Yong-Sun;Kim, Sung-Kyu
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.1088-1093
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    • 2010
  • The Smart bi-directional pile load test with variable end plate overcomes the shortcoming of the Osterberg cell test. It is possible that the ultimate bearing capacity of piles can be known by using two different end plates. The first step is to measure end bearing capacity with smaller end plate and the second step is similar to the conventional O-cell test. In this study, model test was performed to evaluate the smart bi-directional pile load test in sand. Vertical displacement of the model pile were messured at the axial loading condition.

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Testing of RC Corner Beam-column Joints under Bidirectional Loading (이방향 하중을 받는 모서리 보-기둥 접합부의 내진성능 평가)

  • Han, Sang Whan;Chang, Yong Seok;Lee, Chang Seok
    • Journal of the Earthquake Engineering Society of Korea
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    • v.24 no.4
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    • pp.189-196
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    • 2020
  • In this study, two full-scale gravity load-designed reinforced concrete corner beam-column joints were tested by being subjected to uniand bi-directional cyclic lateral loading. The test variable was loading type: uni- or bi-directional loading. To investigate the effect of the loading type on the cyclic behavior of joint specimens, damage progression, force-deformation relation, contribution of joint deformation to total drift, joint stress-strain response, and cumulative energy dissipation were investigated. The test data suggest that bidirectional loading can amplify damage accumulation in the joint region.

Experimental Study on the Calibration of Bi-directional High Pressure Pile Load Test (양방향 고유압 말뚝재하시험장치의 보정에 관한 실험적 연구)

  • Choi, Yongkyu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.5C
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    • pp.303-311
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    • 2008
  • In the case of bi-directional high pressure pile load test with double-acting jack, the shortcomings of bi-directional pile load test with single-acting jack could be solved, low-cost of test could be sure, the limits of loading capacity could be overcome and quality assurance of service plie could be confirmed. In this study, to confirm the stability, the reliability and the application of bi-directional high pressure pile load test with double-acting jack, the calibration test for high pressure oil jacks, the length of high pressure hose and tunable high pressure pipe system were performed. As a result, credibility was very high because the reliability of test results was approached at about 1.0.

Numerical Analyses of O-Cell Load Test on Pile (양방향말뚝재하시험의 수치해석)

  • Joo, Yong-Sun;Kim, Nak-Kyoung;Kim, Woong-Jin;Park, Jong-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.748-753
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    • 2008
  • Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurisation causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. Bi-directional load tests using O-cell are now becoming common practice around the world, particularly where the loads to be applied are high or where it is not convenient to perform top-down loading tests. In the study, calculate ultimate capacity of bi-directional load test using FEM and beam on elasto-plastic foundation theory.

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A Study of Point Selection for Loading Cells in Bi-directional Pile Load Test (양방향재하시험에서 재하장치 위치 선정에 관한 연구)

  • Yoon, Minseung;Kim, Junwoo;Kim, Myunghak
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.10
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    • pp.11-16
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    • 2013
  • Success or failure of the bi-directional pile load test for drilled shaft depends on point selection for loading cells, that is balanced location both uplift force and downward force. Methods to evaluate the ultimate unit side resistance in rockmass layer in both domestic and foreign are based on the uniaxial compression strength of rock core, which can hardly be obtained in domestic rockmass layers which are weathered rockmass layer and soft rockmass layer with very low RQD. Therefore, this study suggested the relation charts between the revised SPT N values and developed unit side resistance of each different layers, which were obtained from bi-directional pile load tests in various domestic sites. To evaluate the appropriateness of the relation charts, the developed unit side resistances from the relation charts were used to select the loading cell position and compared with the measured unit side resistances from field pile load test. Results showed that the developed side resistance from relation charts and the measured side resistance of weathered soil layer and weathered rock layer were very close. Average developed side resistance($1,325kN/m^2$), which are average of upper soft rock layer of loading device($1,151kN/m^2$) and lower($1,500kN/m^2$), was similar with the estimated value ($1,250kN/m^2$).

Damage Assessment of RC Column-Bent Pier under Bidirection Loading (이축 하중을 받는 이주형 철근콘크리트 교각의 손상도평가)

  • Park Chang Kyu;Lee Beom Gi;Yun Sang Chul;Chung Young Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.203-206
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    • 2005
  • Reinforced concrete(RC) column-bent piers represent one of the popular piers used in highway bridges of Korea. Seismic performance of RC column-bent piers under bi-directional seismic loadings was experimentally investigated. Six column bent piers were constructed with two circular supporting columns which were made in 400 mm diameter and 2,000 mm height. Test parameters are different transverse reinforcement ratio and loading pattern. Three specimens were loaded with bi-directional lateral forces which were main cyclic loads in the longitudinal direction and sub-cyclic loads in the transverse direction. Other three specimens were loaded in the opposite way. Test results indicated that lateral strength and ductility of the latter specimens were bigger than those of the former specimens. Plastic hinge was formed with the spall of cover concrete and the fracture of the longitudinal reinforcing steels in the bottom part of two supporting columns for the former three specimens. Similar behavior was observed in the top and bottom parts of two supporting columns for the latter three specimens.

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A Study on the Measurement of End Bearing Capacity for Large Diameter Drilled Shaft Constructed in Fault Zone Using the Static Bi-directional End Leading Test (양방향 선단재하시험을 이용한 단층파쇄대에 시공된 대구경 현장타설말뚝의 선단지지력 측정 연구)

  • 정창규;정성민;황근배;최용규
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.135-143
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    • 2004
  • In the land section of marine bridge construction site, to confirm the end bearing of large diameter drilled shaft constructed in the fault zone which was discovered unexpectedly, the hi-directional end loading tests were performed. The objectives of this study are to confirm the end bearing of the pile constructed in fault zone and the increasing effect of end bearing after grouting the base ground beneath the pile toe. After grouting the pile base ground, the settlement of pile base decreased considerably and the pile base resistance increased more than twice.

Evaluation of Load Transfer Characteristics of Barrette Pile Based on Bi-directional Loading Tests (양방향 재하시험결과를 활용한 바렛말뚝의 하중전이특성 평가)

  • Park, Seong Wan;Lim, Dae Sung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.2C
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    • pp.41-49
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    • 2009
  • Due to the increased size of civil infrastructure and the cost of materials, the needs exists for utilizing large sized cast-inplace piles in lieu of conventional precast piles. Among them, the barrette pile has become more commonly used in fields where a diaphragm wall is the retaining wall, to improve workability and economical efficiency, and to ensure hole stability under deep soil layers. In this paper, the bearing capacity and displacement characteristics of the barrette pile are evaluated by using the bi-directional loading test data obtained from four different sites. In addition, the design value of pile shaft resistance, ${\beta}$, is assessed with previous literatures and load transfer analysis. Finally, numerical analyses were performed to analyze the load-displacement behavior, and the interface effect on the piles, using the 3-dimensional finite element method.

A Scale-Effect of O-Cell Pile Load Test with Variable End Plate (가변선단재하판을 이용한 양방향말뚝재하시험의 치수 효과)

  • Joo, Yong-Sun;Kim, Nak-Kyung;Kim, Ung-Jin;Park, Jong-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.884-890
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    • 2009
  • The bi-directional pile load test with variable end plate overcomes the shortcoming of the Osterberg cell test. It is possible that the ultimate bearing capacity of the bi-direction can be known by using the loading of the end plate and two step procedures. The first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell, operated with end plate of 3 type on sand layer according to the relative density, loose, medium and dense conditions.

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