Calibration of Resistance Factors for Axially Loaded Concrete Piles Driven into Soft Soils

The evaluation of axial load resistance of piles driven into soft Louisiana soils based on reliability theory is presented. Forty-two square precast, prestressed, concrete piles that were tested to failure were included in the investigation. The predictions of pile resistances were based on static analysis (α-method for clay and Nordlund method for sand) and three cone penetration test (CPT) direct methods: the Schmertmann, De Ruiter–Beringen, and Bustamante–Gianeselli methods. In addition, dynamic measurements with signal matching analysis of pile resistances using CAPWAP, which is based on the measured force and velocity signals obtained near the pile top during driving, were evaluated. The Davisson and modified Davisson interpretation methods were used to determine the measured ultimate load-carrying resistances from pile load tests. The predicted ultimate pile resistances obtained by using the different prediction methods were compared with the measured resistances determined from pile load tests. Statistical analyses were carried out to evaluate the capability of the prediction design methods to estimate the measured ultimate pile resistance of driven piles. The results showed that the static method overpredicted the pile resistance, whereas the dynamic measurement with signal matching analysis (CAPWAP end-of-driving and 14-day beginning-of-restrike) underpredicted the pile resistance. Of the three direct CPT methods, the De Ruiter–Beringen method was the most consistent prediction method with the lowest coefficient of variation. Reliability-based analyses, by using the first-order, second-moment method, also were conducted to calibrate the resistance factors (φ) for the investigated pile design methods. The resistance factors for different design methods were determined and compared with AASHTO recommendation values. The calibration showed that De Ruiter–Beringen method has a higher resistance factor (φDe Ruiter = 0.64) than the other two CPT methods.

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Development of Combined Pile-CPT Methods for Estimating the Ultimate Axial Capacity of PPC Piles Driven in Different Soil Categories in Louisiana

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198120907325 ◽

2020 ◽

Vol 2674 (2) ◽

pp. 313-327

Author(s):

Murad Y. Abu-Farsakh ◽

Mohsen Amirmojahedi ◽

George Z. Voyiadjis

Keyword(s):

Prestressed Concrete ◽

Technical Committee ◽

Estimation Accuracy ◽

Pile Capacity ◽

Resistance Factors ◽

Axial Capacity ◽

Load Tests ◽

Pile Load Tests ◽

Log Normal ◽

The Individual

The cone and piezocone penetration tests (CPT, PCPT) have been widely acknowledged as useful in-situ testing tools for subsurface investigation, characterization of soil type, and evaluation of different soil properties. Because of similarity between the cone and pile, the evaluation of axial pile capacity was one of initial applications of the CPT/PCPT. A previous study conducted by the authors on 80 pile load tests of precast prestressed concrete (PPC) piles demonstrated that some pile-CPT methods are able to predict the ultimate axial pile capacity with better accuracy than other methods. These methods include: Schmertmann, De Ruiter and Beringen, Laboratoire Central des Ponts et Chaussées (LCPC), European Regional Technical Committee 3 (ERTC3), University of Western Australia (UWA), probabilistic, and University of Florida (UF) methods. The results of these seven pile-CPT methods were compared and their performance was examined for different soil categories where different percentages of pile capacity contribution is because of sandy layers. The log-normal distribution of the estimated to measured pile capacity for these pile-CPT methods was adopted to develop combined pile-CPT methods that optimize the estimation accuracy of axial pile capacity in different soil categories. Reliability analysis using Monte Carlo Simulation (MCS) was used to evaluate the resistance factors ( ϕ) and efficiency ( ϕ/ λR) of the individual and combined pile-CPT methods. Results of analysis of 80 pile load tests demonstrated the advantage of using the combined pile-CPT methods over the individual methods in relation to improving the accuracy of estimating the ultimate axial pile capacity and having better resistance factors.

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Evaluation of pile load tests in the Edmonton area

Canadian Geotechnical Journal ◽

10.1139/t81-034 ◽

1981 ◽

Vol 18 (2) ◽

pp. 313-316 ◽

Cited By ~ 1

Author(s):

S. Thomson

Keyword(s):

Test Data ◽

Carrying Capacity ◽

Vertical Movement ◽

Load Carrying Capacity ◽

Design Procedures ◽

Concrete Piles ◽

Load Carrying ◽

Load Tests ◽

Pile Load Tests

The design of cast-in-place concrete piles is essentially empirical; hence, an examination of commercial pile load tests is of value. The test data of four pile load tests consisted of the vertical movement of the top of the pile and the load on top of the pile. It was therefore necessary to calculate the shaft and base loads assuming that the till was homogeneous with regard to strength over the length of the pile.The results of the back analyses suggest that the design procedures are valid within practical limits for the prediction of load carrying capacity and for immediate settlement.

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Simulated Seismic Load Tests on Prestressed Concrete Piles and Pile-Pile Cap Connections

PCI Journal ◽

10.15554/pcij.11011990.42.61 ◽

1990 ◽

Vol 35 (6) ◽

pp. 42-61 ◽

Cited By ~ 17

Author(s):

Pam Hoat Joen ◽

Robert Park

Keyword(s):

Prestressed Concrete ◽

Seismic Load ◽

Concrete Piles ◽

Pile Cap ◽

Load Tests

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Cast-in-place bored piles on soft rock under artesian pressures

Canadian Geotechnical Journal ◽

10.1139/t84-075 ◽

1984 ◽

Vol 21 (4) ◽

pp. 684-698 ◽

Cited By ~ 3

Author(s):

Hari D. Sharma ◽

S. Sengupta ◽

Glen Harron

Keyword(s):

Soft Rock ◽

Load Test ◽

Rock Surface ◽

Weathered Rock ◽

Concrete Piles ◽

Geotechnical Investigations ◽

Load Tests ◽

Undrained Strength ◽

Pile Load Tests ◽

A Site

This paper outlines the geotechnical investigations and axial compression, pullout, and lateral pile load tests that were carried out at a site where cast-in-place bored concrete piles were installed. These piles were designed to bear on top of soft weathered rock surface that was under artesian pressures. Pile load test results have been compared with theoretically calculated pile capacities. It has been found that in areas of high artesian pressures in bedrock axial compressive pile load capacities theoretically estimated by conventional methods were significantly higher than the values obtained from load tests. Recommendations have been made that representative exposed bedrock samples be tested to determine their undrained strength, and these values be used for estimating theoretical pile capacities. Construction problems encountered during pile installation, such as locating the top of weathered bedrock without penetrating through water-bearing layers that were under artesian pressures, are presented briefly and a solution provided to install belled piles on top of bedrock is discussed. Key words: bored concrete piles, construction problems, load tests, soft weathered rock under artesian pressures, ultimate pile load capacities.

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Pile load tests for the Calgary Air Terminal building

Canadian Geotechnical Journal ◽

10.1139/t83-038 ◽

1983 ◽

Vol 20 (2) ◽

pp. 353-361

Author(s):

J. Bertok ◽

M. Berezowski

Keyword(s):

Technical Note ◽

Load Test ◽

Load Testing ◽

Test Results ◽

Concrete Piles ◽

Building Foundation ◽

History Of ◽

Load Tests ◽

Pile Load Tests ◽

Pile Type

This technical note describes a case history of pile load tests for the Calgary Air Terminal building. One drilled, cast-in-place, concrete caisson, socketed into bedrock, and compacted expanded-base concrete piles were tested and evaluated to select a pile type that would support column loads up to 6700 kN. This note describes the pile test program, interprets the load test results, and summarizes the pile specifications and installation. Keywords: building foundation, piles, load testing, interpretation, installation.

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Lateral Load Tests on Prestressed Concrete Piles Supporting Integral Abutments

PCI Journal ◽

10.15554/pcij.09012004.70.77 ◽

2004 ◽

Vol 49 (5) ◽

pp. 70-77 ◽

Cited By ~ 4

Author(s):

Edwin G. Burdette ◽

J. Brandon Tidwell ◽

E. Ingram ◽

David W. Goodpasture ◽

Samuel C. Howard ◽

...

Keyword(s):

Prestressed Concrete ◽

Lateral Load ◽

Concrete Piles ◽

Integral Abutments ◽

Load Tests

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Evaluation of 18 Direct CPT Methods for Estimating the Ultimate Pile Capacity of Driven Piles

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198119833365 ◽

2019 ◽

Vol 2673 (9) ◽

pp. 127-141 ◽

Cited By ~ 2

Author(s):

Mohsen Amirmojahedi ◽

Murad Abu-Farsakh

Keyword(s):

Prestressed Concrete ◽

Dimensional Space ◽

Soil Classification ◽

Cumulative Probability ◽

In Situ Tests ◽

Pile Capacity ◽

Concrete Piles ◽

Pile Penetration ◽

Tip Resistance ◽

Load Tests

Cone and piezocone penetration tests (CPT, PCPT) are widely acknowledged to be useful and powerful in-situ tests for soil classification and characterization, and for evaluating different soil properties, such as strength and consolidation parameters. Due to similarity, between the cone and the pile penetration, CPT data have been used effectively for estimating ultimate pile capacity. Researchers have developed various direct CPT methods to estimate the ultimate capacity of piles ( Qp) from CPT/PCPT data (tip resistance and sleeve friction) with depth. In this study, the measured ultimate pile capacities ( Qp) obtained from static load tests on 80 square precast prestressed concrete piles in Louisiana were used to evaluate 18 direct pile-CPT methods for estimating ultimate pile capacity. Two approaches were used. In the first approach, three criteria (best fit line, arithmetic mean and standard deviation, and cumulative probability of Qp/Qm) were adopted, and the sum of ranking of all criteria was used to determine the final ranking of each method. A second approach, multidimensional unfolding, was used to display the ranking data in a two-dimensional space. This approach helps to reveal the typical ranking of the pile-CPT methods, the extent of agreement between the piles, the existence of outliers among the piles, and the similarity between the CPT methods. Based on the results of this study, Bustamante and Gianeselli (LCPC), probabilistic, UF, Philipponnat, CPT2000, UWA, De Ruiter and Beringen, and Schmertmann were found to be the best CPT methods (in order) for estimating the ultimate pile capacity of driven PPC piles.

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