Evaluation of axial performance of tapered piles from centrifuge tests

2000 ◽  
Vol 37 (6) ◽  
pp. 1295-1308 ◽  
Author(s):  
M Hesham El Naggar ◽  
Mohammed Sakr
Keyword(s):  
Analytical Solution ◽  
Reasonable Agreement ◽  
Compressive Loading ◽  
Axial Loading ◽  
Centrifuge Modeling ◽  
Cohesionless Soil ◽  
Scale Model ◽  
Rational Approach ◽  
Centrifuge Tests ◽  
Cylindrical Piles

The performance of tapered piles under axial compressive loading was investigated using centrifuge model tests. Model tapered and cylindrical piles were installed in cohesionless soil and subjected to axial loading. The objectives of this study were to understand the performance characteristics of tapered piles and develop a rational approach for their design. The results of axial compressive loading tests on 12 one-tenth scale model piles with different taper angles in a centrifuge setup are presented and discussed. Six piles were instrumented and six piles were not. The load distribution along the shaft of instrumented piles was measured and the results were compared with an analytical solution in terms of the taper coefficient Kt. The comparison showed a reasonable agreement between Kt values established from the experiments and those obtained from the analytical solution. A simple rational approach was proposed for the design of tapered piles. The proposed approach was used to calculate the bearing capacity of the tested piles, and reasonable agreement with the measured values was obtained. The results of this study suggest that the pile taper should be limited to the top 20-25 pile diameters of the pile length for optimum efficiency.Key words: tapered piles, pile capacity, axial performance, centrifuge modeling, shaft resistance.

Load transfer of fibre-reinforced polymer (FRP) composite tapered piles in dense sand

2004 ◽  
Vol 41 (1) ◽  
pp. 70-88 ◽  
Author(s):  
Mohammed Sakr ◽  
M Hesham El Naggar ◽  
Moncef Nehdi
Keyword(s):  
Analytical Solution ◽  
Load Transfer ◽  
Compressive Loading ◽  
Centrifuge Modeling ◽  
Rational Approach ◽  
Dense Sand ◽  
Reinforced Polymer ◽  
Cylindrical Piles ◽  
Confining Pressures ◽  
Fibre Reinforced Polymer

This paper describes an experimental study conducted using a large, laboratory-scale testing facility to test pile segments at different stress levels. The objectives of the study were twofold: to examine the load-transfer mechanism of tapered piles in compression, and to evaluate the effect of pile material on pile performance characteristics. The results of axial compressive loading tests on 26 pile load tests were presented using fibre-reinforced polymer (FRP) concrete composite tapered piles and steel piles. Two installation techniques were used, including conventional head driving and toe driving using a new technique. Piles were tested at different confining pressures to represent a pile segment at depths of 4.0 and 8.0 m. The load distribution along the pile shafts was measured and the results were compared with those from an analytical solution in terms of the taper coefficient Kt. The comparison showed reasonable agreement between Kt values established from the experiments and those obtained from the analytical solution. The measured toe resistance of tapered and cylindrical piles was compared with those from the analytical solution. A simple rational approach was proposed for the design of tapered piles.Key words: tapered piles, FRP, pile capacity, axial performance, centrifuge modeling, shaft resistance, toe resistance.

scholarly journals Using Finite Element Approach for Crashworthiness Assessment of a Polymeric Auxetic Structure Subjected to the Axial Loading

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1312 ◽  
Author(s):  
Ali Farokhi Nejad ◽  
Roozbeh Alipour ◽  
Mozafar Shokri Rad ◽  
Mohd Yazid Yahya ◽  
Seyed Saeid Rahimian Koloor ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Compressive Loading ◽  
Computational Cost ◽  
Axial Loading ◽  
Polyurethane Foams ◽  
Absorption Enhancement ◽  
Aspect Ratios ◽  
Auxetic Structures ◽  
Element Approach ◽  
Tube Versus

Polyurethane foams are one of the most common auxetic structures regarding energy absorption enhancement. This present study evaluates the result reliability of two different numerical approaches, the H-method and the P-method, to obtain the best convergence solution. A polymeric re-entrant cell is created with a beam element and the results of the two different methods are compared. Additionally, the numerical results compare well with the analytical solution. The results show that there is a good agreement between converged FE models and the analytical solution. Regarding the computational cost, the P-method is more efficient for simulating the re-entrant structure subjected to axial loading. During the second part of this study, the re-entrant cell is used for generating a polymeric auxetic cellular tube. The mesh convergence study is performed on the cellular structures using the H- and P- methods. The cellular tube is subjected to tensional and compressive loading, the module of elasticity and Poisson’s ration to calculate different aspect ratios. A nonlinear analysis is performed to compare the dynamic response of a cellular tube versus a solid tube. The crashworthiness indicators are addressed and the results are compared with equivalent solid tubes. The results show that the auxetic cellular tubes have better responses against compressive loading. The primary outcome of this research is to assess a reliable FE approach for re-entrant structures under axial loading.

Uplift behaviour of tapered piles established from model tests

2000 ◽  
Vol 37 (1) ◽  
pp. 56-74 ◽  
Author(s):  
M Hesham El Naggar ◽  
Jin Qi Wei
Keyword(s):  
Load Transfer ◽  
Compressive Loading ◽  
Compressive Load ◽  
Tensile Load ◽  
Confining Pressure ◽  
Cohesionless Soil ◽  
Uplift Capacity ◽  
Experimental Modelling ◽  
Confining Pressures ◽  
Load Tests

Tapered piles have a substantial advantage with regard to their load-carrying capacity in the downward frictional mode. The uplift performance of tapered piles, however, has not been fully understood. This paper describes the results of an experimental investigation into the characteristics of the uplift performance of tapered piles. Three instrumented steel piles with different degrees of taper were installed in cohesionless soil and subjected to compressive and tensile load tests. The soil was contained in a steel soil chamber and pressurized using an air bladder to facilitate modelling the confining pressures pertinent to larger embedment depths. The results of this study indicated that the pile axial uplift capacity increased with an increase in the confining pressure for all piles examined in this study. The ratios of uplift to compressive load for tapered piles were less than those for straight piles of the same length and average embedded diameter. The uplift capacity of tapered piles was found to be comparable to that of straight-sided wall piles at higher confining pressure values, suggesting that the performance of actual tapered piles (with greater length) would be comparable to that of straight-sided wall piles. Also, the results indicated that residual stresses developed during the compressive loading phase and their effect were more significant on the initial uplift capacity of piles, and this effect was more pronounced for tapered piles in medium-dense sand.Key words: tapered piles, uplift, axial response, load transfer, experimental modelling.

scholarly journals First results of pipe pile static load test in small laboratory scale

2018 ◽  
Vol 251 ◽  
pp. 04038 ◽  
Author(s):  
Michal Baca ◽  
Jaroslaw Rybak
Keyword(s):  
Static Load ◽  
Axial Loading ◽  
Laboratory Scale ◽  
Load Test ◽  
Scale Model ◽  
Small Scale ◽  
Small Laboratory ◽  
Static Load Test ◽  
First Results ◽  
Load Tests

Presented laboratory testing program of tubular steel piles is a part of a bigger research program which contained static load tests in full scale and numerical simulations of conducted research. The main goal of the research is to compare static load tests with different working conditions of a shaft. The presented small scale model tests are the last part of the research. The paper contains the testing methodology description and first results of model pile axial loading. The static load tests in a small laboratory scale were conducted in a container filled with uniformly compacted medium sand (MSa). The first results of the investigation are presented in this paper, with the comparison of two pile capacities obtained for different roughness of the pile shaft (skin friction). The results are presented as load-displacement curves obtained by means of the Brinch-Hansen 80% method.

Evaluation of Dynamic Behavior of Pile Foundations for Interim Storage Facilities Through Geotechnical Centrifuge Tests

2002 ◽  
Author(s):  
Shizuo Tsurumaki ◽  
Hiroyuki Watanabe ◽  
Akira Tateishi ◽  
Kenichi Horikoshi ◽  
Shunichi Suzuki
Keyword(s):  
Dynamic Behavior ◽  
Experimental Studies ◽  
Centrifuge Modeling ◽  
Pile Foundations ◽  
Soil Conditions ◽  
Confining Stress ◽  
Geotechnical Centrifuge ◽  
Centrifuge Tests ◽  
Interim Storage ◽  
Storage Facilities

In Japan, there is a possibility that interim storage facilities for recycled nuclear fuel resources may be constructed on quaternary layers, rather than on hard rock. In such a case, the storage facilities need to be supported by pile foundations or spread foundations to meet the required safety level. The authors have conducted a series of experimental studies on the dynamic behavior of storage facilities supported by pile foundations. A centrifuge modeling technique was used to satisfy the required similitude between the reduced size model and the prototype. The centrifuge allows a high confining stress level equivalent to prototype deep soils to be generated (which is considered necessary for examining complex pile-soil interactions) as the soil strength and the deformation are highly dependent on the confining stress. The soil conditions were set at as experimental variables, and the results are compared. Since 2000, the Nuclear Power Engineering Corporation (NUPEC) has been conducting these research tests under the auspices on the Ministry of Economy, Trade and Industry of Japan.

An Analytical Solution for Calculating Stresses on Lap Patches Used on Pipes and Pressure Vessels

2008 ◽  
Author(s):  
Chithranjan Nadarajah ◽  
Guido L. Spinelli
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Reasonable Agreement ◽  
Analytical Approximation ◽  
Pressure Vessels ◽  
Short Term ◽  
Analytical Results ◽  
Patch Repairs ◽  
Petrochemical Industries

Lap patch repairs are used regularly in petrochemical industries as temporary repairs for short term operations. In this paper a simple methodology is proposed on how to calculate the stresses on a lap patch using simple analytical approximation. The simple analytical results are compared with finite element results and they are found to be in reasonable agreement.

Impact Response of Thin-Walled Tubes: A Prospective Review

2012 ◽  
Vol 165 ◽  
pp. 130-134 ◽  
Author(s):  
Fauziah Mat ◽  
K. Azwan Ismail ◽  
S. Yaacob ◽  
O. Inayatullah
Keyword(s):  
Compressive Loading ◽  
Axial Loading ◽  
Geometrical Parameters ◽  
Axial Deformation ◽  
Thin Walled Structures ◽  
Structural Applications ◽  
Thin Walled ◽  
Energy Absorbers ◽  
Energy Absorbing ◽  
The Impact

Thin-walled structures have been widely used in various structural applications asimpact energy absorbing devices. During an impact situation, thin-walled tubesdemonstrate excellent capability in absorbing greater energy through plastic deformation. In this paper, a review of thin-walled tubes as collapsible energy absorbers is presented.As a mean of improving the impact energy absorption of thin-walled tubes, the influence of geometrical parameters such as length, diameter and wall thickness on the response of thin-walled tubes under compression axial loading are briefly discussed. Several design improvements proposed by previous researchers are also presented. The scope of this review is mainly focus on axial deformation under quasi-static and dynamic compressive loading. Other deformations, such as lateral indentation, inversion and splitting are considered beyond the scope of this paper. This review is intended to assist the future development of thin-walled tubes as efficient energy absorbing elements.

Centrifuge tests on axially loaded tapered piles with different cross-sections under compressive and tensile loading

2021 ◽  
Author(s):  
Alireza Shabanpour ◽  
Mahmoud Ghazavi
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Compressive Loading ◽  
Tensile Tests ◽  
Construction Costs ◽  
Geotechnical Centrifuge ◽  
Head Displacement ◽  
Centrifuge Tests ◽  
Uniform Cross Section ◽  
Pile Length

The compressive behavior of tapered piles, particularly those with circular cross-sections, has been investigated during the last few decades. However, the tensile behavior of such piles has been rarely studied in the literature. In this paper, 12 static axial tests, including six compressive and also six tensile tests, were performed on instrumented piles with uniform and tapered cross-sections by using a geotechnical centrifuge. Three of the piles had correspondingly circular, square and X-shaped uniform cross-sections along their length, while the other three ones were non-uniform (tapered), all of which had the same length and volume. The results are presented in three main forms: the variation of load versus pile head displacement, the distribution of axial force along the pile length, and the distribution of the unit shaft resistance along the pile length. The behavior of tapered piles is compared with that of uniform cross-section piles. The results confirm the superiority of tapered piles over uniform cross-section piles in terms of load-bearing capacity and construction costs under both tensile and compressive loading.

Numerical and physical modeling of bar deformation under axial loading in the channel. Part 1

2020 ◽  
Author(s):  
N.T. Ovchinnikov ◽  
F.D. Sorokin
Keyword(s):  
Numerical Model ◽  
Analytical Solution ◽  
Physical Modeling ◽  
Axial Loading ◽  
Loss Of Stability ◽  
Load History ◽  
Nonlinear Bending ◽  
Initial Shape ◽  
Bending Waves ◽  
One Step

In two parts of the work, numerical and physical modeling of the deformation of the bar in the channel under axial compression is carried out. The regularities of nonlinear bending of the bar in the plane are revealed. Bar shapes are determined by the load history and can differ at the same force value. The solution is to find the shape with the lowest potential energy. The first part of the work describes the numerical model of the bar and the results of its application. The shapes of the bar bending under gradual loading are obtained, the studies coinciding with V.I. Feodosev’s analytical solution. Further research shows that the solution to the problem has a more complex ramified structure with various additional shapes. Deformation of the bar under gradual loading occurs in the form of a sequential variant appearance of bending waves in the bar under forces determined by the degree of non-uniformity of the lengths of potentially unstable sections and forming a range of shape instability. In variant transitions from one initial shape with a loss of stability, it is possible to obtain various subsequent shapes that differ in the sequence of deformation of the sections with one number of half-waves, or the number of generated half-waves. When a straight bar is loaded in one step, an increase in the force leads to a sequential increase in the number of bending half-waves in the corresponding ranges of the existence of shapes. The results obtained can be applied to the analysis of the operation of such bar objects as drill, casing, tubing strings in the well and cased pipelines, pipelines in the well and tunnel.

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