Axial monotonic and cyclic compression behaviour of hollow-bar micropiles

Drbe, Osama; Naggar, M. Hesham El

doi:10.1139/cgj-2014-0052

Cited by 42 publications

(11 citation statements)

References 8 publications

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“…In practice, the Federal Highway Administration (FHWA) guidelines for micropile design and construction suggest the range of bond strength (α bond ) values at the pile-to-ground interface as the main factor for calculating the design capacity considering the grouting method (FHWA 2005). Several researchers have carried out various studies to derive high bond strength by modifying the construction method and the structure compositions of the pile to improve the bearing performance of the micropile compared to the conventional pile (Gomez et al 2008;Bennet and Hothem 2010;Drbe and El Naggar 2014;Abd Elaziz and El Naggar 2015;Vickars and Clemence 2000;El Sharnouby and El Naggar 2012;Papadopoulou et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Field study on axial bearing capacity and load transfer characteristic of waveform micropile

Jang

Han

2018

Can. Geotech. J.

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The waveform micropile is an advanced construction method that combines the concept of the conventional micropile with the jet grouting method. This new form of micropile was developed to improve shaft resistance, and has enabled a higher bearing capacity and greater cost efficiency. Two field tests were conducted to examine field applicability and to verify the effects of bearing capacity enhancement. In particular, waveform micropile construction using the jet grouting method was performed to evaluate the viability of waveform micropile installation. After testing, the surrounding ground was excavated to check the shape of the waveform micropile. The result showed that waveform micropiles can be installed by adjusting the grouting time and pressure. In the loading tests, the bearing capacity of the waveform micropile increased by 1.4–2.3 times that of the conventional micropile, depending on the shape of the micropile. The load transfer analysis using the strain gauge data showed that the waveform micropile increases the shaft resistance in the soil layer. This not only decreases pile settlement, but also contributes to the increase of overall bearing capacity. The overall results clearly demonstrate that the waveform micropile is an enhanced construction method that can improve bearing capacity.

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Section: Introductionmentioning

confidence: 99%

Field study on axial bearing capacity and load transfer characteristic of waveform micropile

Jang

Han

2018

Can. Geotech. J.

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“…Early studies indicated that the a bond values for type B, which correspond to the pressurized grouting characteristics of the hollow-bar micropile, can lead to underestimation of the bearing capacity of hollow-bar micropiles. Therefore, various follow-up studies have been performed to propose reasonable design parameters considering the in situ conditions of the hollow-bar micropile [1,4,6,11,24].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the shape effect on the axial performance of a waveform micropile by centrifuge model tests

Jang

Han

2018

Acta Geotech.

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A new type of micropile, the waveform micropile, has been developed to provide improved load-bearing capacity compared with that of a conventional micropile. The waveform micropile has a wave-shaped grout with a partially enlarged shear key formed by the jet grouting method on the cylindrical shaft of the micropile. Previous research has determined that the waveform micropile can be installed faster than the conventional micropile and that the bearing capacity increases as the wave-shaped grout provides additional shaft resistance between the ground and the grout. In this study, a series of centrifuge model tests were conducted on the waveform micropile model with various wave-shaped grouts to analyze the relationship between the arrangement of the shear key and the load-bearing mechanism of the waveform micropile. The load-settlement relationship and the load-transfer mechanism were analyzed based on the test results of six test micropiles, including three waveform micropiles with a single shear key at various depths, one waveform micropile with a multiple shear key along the pile depth, and two micropiles with only a cylindrical shape. The test results showed that the ultimate bearing capacity of the waveform micropile was over two times greater than that of the conventional micropile. The rate of increase in the bearing capacities of each waveform micropile differed with the shape of the shear key. Furthermore, the characteristics of the load-sharing ratio due to the shaft resistance and end bearing varied depending on the shape of the waveform micropiles.

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“…Load-displacement in the cycling direction is obtained from numerical analysis, using ABAQUS software [Figs. [5][6]. In comparison models 1 and 2, the loading, unloading and reloading cycles, show different shape for each model.…”

Section: Numerical Analysis and Discussionmentioning

confidence: 98%

“…In the construction industry and related field, several characteristics of different structure, structural elements, substructure and construction materials are numerically, theoretically and experimentally reported in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], but little research has been done on timber structure design. A timber structure state of art has numerically been investigated, to understand seismic resistance by the evaluation of the load, displacement and stress have been applied on the timber structures [1].…”

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confidence: 99%

Timber beam seismic design – A numerical simulation

Namdar¹,

Dong

Liu

2018

Frattura Ed Integrità Strutturale

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In order to design a seismic timber beam, the effect of near-fault ground motion on timber beam has numerically been investigated, with reference to small displacement theory. The simulated near-fault ground motion is applied on the fixed base of a timber frame model. The beam is placed in single span of a timber frame. The beam has two different length sizes of 1.8 and 3.3 meters. The seismic load-displacement, seismic load-strain and strain-displacement have been calculated for all models and shown in graphs. The beam is designed with nonlinear analysis method and some mechanical properties for all models have been used, in numerical analysis. The numerical analysis results indicate that, the inertial interaction, energy dissipation and nonlinear deformation of beams in timber frames have directly related with frame span. In beams with a smaller length, higher seismic loading caused lower displacement. The displacement is reduced by reducing the length of the beam. The inertial interaction, energy dissipation and nonlinear deformation are changed respect to the length of the beam. The innovation of this paper is to develop cycling graphs by using ABAQUS, to improve design of timber frame and give an adequate explanation of seismic behavior of timber beam.

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Axial monotonic and cyclic compression behaviour of hollow-bar micropiles

Cited by 42 publications

References 8 publications

Field study on axial bearing capacity and load transfer characteristic of waveform micropile

Field study on axial bearing capacity and load transfer characteristic of waveform micropile

Analysis of the shape effect on the axial performance of a waveform micropile by centrifuge model tests

Timber beam seismic design – A numerical simulation

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