Discussion of “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Zhang, Jian; Zhang, Qian‐qing; Feng, Ruo-feng; Liu, Shan-wei; Zhang, Shimin

doi:10.1139/cgj-2016-0588

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…We agree that the jacking of adjacent piles could cause a tensile effect when the center-to-center distance between two adjacent piles is small. However, as this is not the case for our study as pointed out by the Discussers (Zhang et al 2017), this question is irrelevant. As explained in the paper, residual forces are usually caused by pile compression, rebound of the soil at the pile base, and the soil strength recovery after installation.…”

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confidence: 69%

Reply to the discussion by Zhang et al. on “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

et al. 2017

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We thank the Discussers for their interest in our paper (Kou et al. 2016). We agree that the jacking of adjacent piles could cause a tensile effect when the center-to-center distance between two adjacent piles is small. However, as this is not the case for our study as pointed out by the Discussers (Zhang et al. 2017), this question is irrelevant. As explained in the paper, residual forces are usually caused by pile compression, rebound of the soil at the pile base, and the soil strength recovery after installation. If the distance between adjacent piles is small, the tensile effect caused by the installation of adjacent piles will push the pile upward and reduce the residual forces in the pile.We were well aware of the temperature effect on the wavelength of fiber Brag grating (FBG) strain sensors during monitoring. It was for this reason that the field tests presented in the paper were conducted in June and July where the temperature variation was small during the day.In the paper, residual force refers to the compressive force caused by the elastic compression of the pile. This elastic compression is mainly caused by jacking force, shaft resistance, and base resistance. The jacking force plays a key role during the process. After installation, the pile recovers from the elastic deformation. There are two types of forces preventing the pile recovering from the elastic deformation after installation. One is the shear force between the soil and pile, which is enhanced due to the dissipation of excess pore-water pressures. The other is the additional downward force caused by the settlement of the ground, which is also caused by the dissipation of pore-water pressures. Note that the additional downward force can prevent the pile from recovering from the elastic deformation. If the additional downward force causes the residual forces to increase, it means that the deformation caused by the additional downward force is larger than the initial elastic deformation. However, this is almost impossible because the force that caused the initial elastic deformation is larger than the additional downward force. Therefore, for a pile after installation, residual forces would decrease until the recovering force, shear force, and additional downward force reach an equilibrium state.The measured base resistance presented in the paper included both annulus resistance of the pile base and soil plug resistance. Figure 4 in the paper shows the arrangement of strain sensors along the test pile. Note that the inner diameter of the test pile was only 250 mm and thus it was difficult to install strain gauges inside the pile. To measure the annulus resistance of the pile base and the soil plug resistance separately, double-walled pile systems have been used for open-ended steel pipe piles in calibration chambers (e.g., Lehane and Gavin 2001;Paik et al. 2003) and in the field (e.g., Ko and Jeong 2015). However, the double-walled pile method is not applicable to concrete piles as the wall thickness is significantly larger than steel pipe ...

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confidence: 69%

Reply to the discussion by Zhang et al. on “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

et al. 2017

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“…To simplify the calculation, the same method as for ordinary reinforced concrete components is adopted, equating the longitudinal reinforcement steel to an equivalent area of high-strength concrete beam with the same modulus [16][17][18]. In this case, the high-strength concrete beam can be considered as a homogeneous elastic material.…”

Section: Calculation Of Cracking Momentmentioning

confidence: 99%

Mechanical Behavior Analysis of High Strength Concrete Beams in Architectural Design: Simplified Calculation Method of Flexural and Shear Bearing Capacity

Peng,

Zhou

2024

TECM

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This study advances the use of high-strength concrete beams in structural engineering by analyzing their flexural behavior. Utilizing a combination of theoretical and empirical methods, the research develops equations for calculating the cracking moment and ultimate load capacity of these beams. Key findings include a shear-bearing capacity calculation model, validated by experimental data, with discrepancies in cracking moment and ultimate load-bearing capacity formulas being only 6.16% and 1.53% respectively. These results offer significant insights for the design and analysis of high-strength concrete beams in architectural engineering, demonstrating high accuracy and stability.

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“…During the pile jacking process, the force locked inside the pile body after the completion of the one-way pile pressing is called the residual stress due to the unloading of the pile top and the failure to fully recover the elastic compression of pile body, which has been comprehensively considered [23][24][25][26][27][28]. The test shows that for partially constrained pile bodies, the lateral pressure affects the vertical stress, and there was a considerable increment of the vertical stress as caused by the pile body.…”

Section: Axial Force Distribution Law For Pile Bodymentioning

confidence: 99%

A Model Test for the Influence of Lateral Pressure on Vertical Bearing Characteristics in Pile Jacking Process Based on Optical Sensors

Wang

Liu

Sang

et al. 2020

Sensors

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Photoelectric integrated testing technology was used to study precast piles during pile jacking at the pile–soil interface considering the influence of the earth and pore water pressures on its vertical bearing performance. The low temperature sensitive fiber Bragg grating (FBG) strain sensors and miniature silicon piezoresistive sensors were implanted in the model pile to test the changes of earth pressure, pore water pressure and pile axial force of the jacked pile at the pile–soil interface, and the influence of lateral pressure on pile axial force was studied. The test results showed that the nylon rod is feasible as a model pile. The FBG strain sensor had a stable performance and monitored changes in the axial force of the model pile in real time. The miniature earth and pore water pressure sensors were small enough to avoid size effects and accurately measured changes in the earth and pore water pressures during the pile jacking process. During pile jacking, the lateral earth pressure increased gradually in depth, and the lateral earth pressure at the same depth tended to decrease at greater depths. Lateral pressures caused the axial force of the pile to increases by a factor of 1–2, where the maximum was 2.7. Therefore, the influence of the lateral pressure must be considered when studying the residual pile stress.

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Discussion of “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Cited by 4 publications

References 6 publications

Reply to the discussion by Zhang et al. on “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Reply to the discussion by Zhang et al. on “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Mechanical Behavior Analysis of High Strength Concrete Beams in Architectural Design: Simplified Calculation Method of Flexural and Shear Bearing Capacity

A Model Test for the Influence of Lateral Pressure on Vertical Bearing Characteristics in Pile Jacking Process Based on Optical Sensors

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