• Title/Summary/Keyword: Ultimate lateral load capacity

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Estimation of Pile Ultimate Lateral Load Capacity in Sand Considering Lateral Stress Effect (응력상태를 고려한 사질토지반에 관입된 말뚝의 극한수평지지력 분석 및 평가)

  • Lee, Jun-Hwan;Paik, Kyu-Ho;Kim, Dae-Hong;Hwang, Sung-Wuk;Kim, Min-Kee
    • Journal of the Korean Geotechnical Society
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    • v.23 no.4
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    • pp.161-167
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    • 2007
  • In this study, ultimate lateral load capacity of piles is analyzed with consideration of lateral stress effect. Based on results obtained in this study, a method for the estimation of ultimate lateral load capacity is proposed. This makes it possible to more realistically estimate the ultimate lateral load capacity under various stress states caused by in-situ soil condition and pile installation process. Calibration chamber test results with various soil conditions were used in the analysis. From the test results, it was found that effect of the lateral stress was greater than that of the vertical stress on the ultimate lateral load capacity of piles. It was also found that, as the relative density increases, displacements required to reach the ultimate state increases, showing relative displacements of around 14% and 18-25% for $D_R$ : 55% and 86%, respectively. Based on results obtained in this study, a methodology for the estimation of ultimate lateral load capacity of piles using correction factors was proposed. Results from proposed method matched well measured results.

Behavior of Laterally Cyclic Loaded Piles Driven into Sand (모래지반에서 반복수평하중을 받는 항타말뚝의 거동)

  • Paik, Kyu-Ho;Park, Won-Woo;Kim, Young-Jun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.913-922
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    • 2009
  • Fourteen model pile load tests using a calibration chamber and instrumented model pile were preformed to investigate the variation of the behaviors of driven piles in sands with soil and lateral cyclic loading conditions. Results of the model tests showed that the first loading cycle generated more than 70% of the pile head rotation developed for 50 lateral loading cycles. Lateral cyclic loading also made an increase of the ultimate lateral load capacity of piles for $K_0$=0.4 and an decrease for $K_0$ higher than 0.4. Higher portion of the increase or decrease in the ultimate lateral load capacity by lateral cyclic loading was generated for the first loading cycle due to densification of loosening of the soil around the pile by lateral cyclic loading. It was also observed that a two-way cyclic loading caused higher ultimate lateral load capacity of driven piles than a one-way cyclic loading. When the pile was in the ultimate state, the maximum bending moment developed in the pile increased with increasing $K_0$ value of soil and was insensitive to the magnitude and number of lateral cyclic loading.

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Lateral Behavior of Driven Piles Subjected to Cyclic Lateral Loads in Sand (모래지반에서 반복수평하중을 받는 항타 말뚝의 수평거동)

  • Paik, Kyu-Ho
    • Journal of the Korean Geotechnical Society
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    • v.26 no.12
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    • pp.41-50
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    • 2010
  • The behavior of laterally cyclic loaded piles is different from that of piles under monotonic loading and depends on soil and load characteristics. In this study, model pile load tests were performed using a calibration chamber to investigate the effects of load characteristics on the behavior of laterally cyclic loaded piles in sand. Results of the model tests show that the ultimate lateral load capacity of laterally cyclic loaded piles decreases linearly with increasing the number of cycles and increases slightly with increasing the magnitude of cyclic lateral loads. When the piles reach the ultimate state, the maximum bending moment developed in the piles decreases linearly with increasing the number of cycles and it occurs at a depth of 0.36 times pile embedded length for all the number of cycles. However, both the magnitude and depth of the maximum bending moment of piles in the ultimate state increase slightly as the magnitude of cyclic lateral loads increases. It is also observed that the cyclic lateral loading generates a decrease in the ultimate lateral load capacity and maximum bending moment for piles in the ultimate state. In addition, based on the model test results, a new empirical equation for the ultimate lateral load capacity of laterally cyclic loaded piles in dense sand is also proposed. A comparison between predicted and measured load capacities shows that the proposed equation reflects satisfactorily the model test results.

Estimation of Ultimate Lateral Load Capacity Using CPT Results Considering Lateral Soil Pressure Distribution (수평토압분포를 고려한 CPT 기반의 말뚝극한수평지지력 산정)

  • Kim, Min-Kee;Kyung, Doo-Hyun;Hong, Jung-Moo;Lee, Jun-Hwan
    • Journal of the Korean Geotechnical Society
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    • v.25 no.2
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    • pp.37-44
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    • 2009
  • In this study, estimation methodology for the pile of ultimation lateral resistance, pu, and ultimate lateral capacity, Pu, is based on the CPT cone resistance $q_c$. Preexistent methodologies for ultimate lateral resistance and ultimate lateral capacity have been generally represented with relative density, vertical effective stresses, and various $K_0$ values which are important for analyzing sandy soil. These methodologies, however, did not consider the horizontal effective stress and the effects of construction site conditions. Therefore, CPT-based methodology for the estimation of the ultimate lateral pile load capacity Hu was proposed. Calibration chamber test results were analyzed and compared with calculated results. The proposed estimation methodology for the pile of $p_u$ can be effectively utilized as alternative to preexistent methods.

The behavior and capacity of lateral loaded pile characteristics in multi-layered sand (사질토 다층지반에 관입된 말뚝의 수평 거동 및 수평 지지력 특성)

  • Kyung, Doo-Hyun;Kang, Beong-Joon;Hong, Jung-Moo;Lee, Jun-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.738-743
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    • 2008
  • Ultimate lateral loaded pile capacity is influenced by soil conditions. Methods of calculating ultimate lateral loaded pile capacity in homogeneous soil were suggested by a lot of previous researchers.(Broms 1964, Petrasovits & Award 1972, Prasad & Chari 1999, Zhang et al. 2005) There is only few homogeneous soil in actual condition, however, it could be not conviction that the methods from previous researchers are correct in multi-layered soil. In this study, the variation of ultimate lateral loaded pile capacity was analyzed in the various multi-layered conditions, ultimate lateral loaded pile capacity was calculated by the methods from previous researchers. For this study, the Lateral Pile Load Tests (LPLT) were performed in calibration chamber, the soil was composed by 3 layers and each layers had a various relative density. The results of LPLT were compared with calculated results from the previous researchers.

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Effects of Loading Method on the Behavior of Laterally Cyclic Loaded Piles in Sand (모래지반에서 재하방법이 반복수평하중을 받는 말뚝의 거동에 미치는 영향)

  • Paik, Kyu-Ho;Kim, Young-Jun;Lee, Seung-Yeon
    • Journal of the Korean Geotechnical Society
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    • v.27 no.3
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    • pp.63-73
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    • 2011
  • The behavior of laterally cyclic loaded piles is affected by the magnitude and number of cycles of cyclic lateral loads as well as loading method (1-way or 2-way loading). In this study, calibration chamber tests were carried out to investigate the effects of loading method of cyclic lateral loads on the behavior of piles driven into sand. Results of the chamber tests show that the permanent lateral displacement of 1-way cyclic loaded piles is developed in the same direction as the first loading, whereas that of 2-way cyclic loaded piles is developed in the reverse direction of the first loading. 1-way cyclic lateral loads cause a decrease of the ultimate lateral load capacity of piles, and 2-way cyclic lateral loads cause an increase of the ultimate lateral load capacity of piles. The change of ultimate lateral load capacity with loading method of cyclic lateral loads increases with increasing number of cycles. It is also observed that the 1-way cyclic loads generate greater maximum bending moment than 2-way cyclic loads for piles in cyclic loading step and generates smaller maximum bending moment for piles in the ultimate state. It can be attributed to the difference in compaction degree of the soil around the piles with loading method of cyclic lateral loads. In addition, it is founded that 1-way and 2-way cyclic lateral loads cause a decrease in the maximum bending moment of piles in the ultimate state compared with that of piles subjected to only monotonic loads.

The behavior characteristic of the laterally loaded pile installed in multi-layered soil (지반층 변화에 따른 수평하중을 받는 말뚝의 거동 특성)

  • Kyung, Doo-Hyun;Hong, Jung-Moo;Lee, Jun-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.533-538
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    • 2009
  • Ultimate lateral loaded pile capacity is influenced by soil conditions. Methods of calculating ultimate lateral loaded pile capacity in homogeneous soil were suggested by a lot of previous researchers.(Broms 1964, Petrasovits & Award 1972, Prasad & Chari 1999) There is only few homogeneous soil in actual condition, however, it could be not conviction that the methods from previous researchers are correct in multi-layered soil. In this study, ultimate lateral capacities were estimated from artificial multi-layered soils and were measured from lateral load test that were composed by various soil conditions. The influence of layered soil conditions were confirmed by comparing with two results.

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Bearing Capacity of Driven H-Piles in Embankment (성토지반에 타입된 H형강 말뚝의 지지거동)

  • 박영호;정경자;김성환;유성근;이재혁;박종면
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.173-182
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    • 2000
  • To find axial and lateral responses of impact-driven H piles in embankment(SM), the H piles are instrumented with electric strain gages, dynamic load test is performed during driving, and then the damage of strain gages is checked simultaneously. Axially and laterally static load tests are performed on the same piles after one to nine days as well. Then load-settlement behavior is measured. Furthermore, to find the set-up effect in H pile, No. 4, 16, 26, and R6 piles are restriked about 1, 2, and 14 days after driving. As results, ram height and pile capacity obtained from impact driving control method become 80cm and 210.3∼242.3ton, respectively. At 15 days after driving, allowable bearing capacity by CAPWAP analysis, which 2.5 of the factor of safety is applied for ultimate bearing capacity, increases 10.8%. Ultimate bearing capacity obtained from axially static load test is 306∼338ton. This capacity is 68.5∼75.7% at yield force of pile material and is 4∼4.5 times of design load. Allowable bearing capacity using 2 of the factor of safety is 153∼169ton. Initial stiffness response of the pile is 27.5ton/mm. As the lateral load increases, the horizontal load-settlement behaves linearly to which the lateral load reaches up to 17ton. This reason is filled with sand in the cavity formed between flange and web during pile driving. As the result of reading with electric strain gages, flange material of pile is yielded at 19ton in horizontal load. Thus allowable load of this pile material is 9.5ton when the factor of safety is 2.0. Allowable lateral displacement of this pile corresponding to this load is 23∼36mm in embankment.

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Experimental study of masonry walls strengthened with CFRP

  • Wei, Chang-Qin;Zhou, Xin-Gang;Ye, Lie-Ping
    • Structural Engineering and Mechanics
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    • v.25 no.6
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    • pp.675-690
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    • 2007
  • In order to study the ductility and the lateral load carrying capacity of the masonry walls strengthened with CFRPs (Carbon Fiber Reinforced Polymer sheets), three pieces of masonry walls subjected to cyclic loads with low frequency and vertical load of constant amplitude have been tested. Two different strengthening methods have been used. The strengthening efficiency is affected by the strengthening method. A simplified calculation approach has been introduced based on the experimental test results, and the theoretical results agree reasonably well with the experimental results. It is found that the critical loads, the critical displacements, the ultimate loads, the ultimate displacements and the ductile coefficients of the masonry walls strengthened with CFRPs improve remarkably (6%~57%). Therefore, the masonry structures strengthened with CFRPs are of better ductility and of better lateral load carrying capacity than the masonry structures without any strengthening measurements.

Analysis of Estimation of Ultimate Lateral Capacity of Pile in Multi-Layered Soil Using CPT Results and Proposal of Modified Lateral Earth Pressure (다층조건에서 CPT를 이용한 말뚝의 극한수평지지력 평가 분석 및 수정 수평토압분포 제안)

  • Hong, Jung-Moo;Kyung, Doo-Hyun;Kang, Beong-Joon;Lee, Jun-Hwan
    • Journal of the Korean Geotechnical Society
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    • v.25 no.6
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    • pp.47-57
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    • 2009
  • In this study, the ultimate lateral load capacity of pile driven into multi-layered soil was estimated using cone penetration test results and a method was proposed to reflect multi-layered soil conditions. For multi-layered specimens prepared with different relative density at different layers, the cone penetration tests and lateral pile load tests were conducted. Based on the test results, measured and estimated values of the ultimate lateral load were compared and analyzed. The estimated results were obtained from the methods proposed by Broms (1964), Petrasovits & Award (1972) and Prasad & Chari (1999). The method was proposed for modifying the earth pressure distribution of Prasad & Chari (1999) to consider multi-layered soil conditions. From the analysis, it was seen that results obtained from the proposed method showed improvement with less data scatter similarly to those obtained from Broms (1964) and Petrasovits & Award (1972)'s methods.