Assessment of Several Nominal Resistance Interpretation Criteria for Drilled Foundations

Kodsy, Antonio; Iskander, Magued; Machairas, Nikolaos

doi:10.1061/(asce)gt.1943-5606.0002733

Cited by 5 publications

(9 citation statements)

References 9 publications

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“…Interpreted (measured) capacities (Q m ) were obtained from the load-settlement curves using the NYU interpretation criterion [47,48], where the capacity is that corresponding to the smallest of the following settlements: (1) the load corresponding to a settlement equal to the elastic shortening of the pile ( PL AE ) plus 0.75 inches (20 mm) per the 2014 New York City Building Code; (2) 5% of the pile diameter; or (3) settlement corresponding to first incidence of plunging or strain-softening resulting in loss of more than 5% of capacity. Calculated and computed capacities are summarized for the 74 piles in Appendix C.…”

Section: Discussionmentioning

confidence: 99%

Insights into Plugging of Pipe Piles Based on Pile Dimensions

Kodsy

Iskander

2022

Applied Sciences

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Preliminary identification of plugging of open-ended pipe piles based on their dimensions, ahead of driving, is explored in this study using data analytics. Piles can be unplugged, plugged, or internally plugged, depending on their dimensions, and geotechnical conditions. Plugging of pipe piles influences both pile capacity and driving behavior; however, the classification assumed at the design time does not always manifest during driving, sometimes resulting in driving difficulties. The relationship between pile plugging and pile dimensions was investigated using a dataset of 74 load tests on pipe piles, where geotechnical profiles were also available. An analytics approach borrowed from data science was adopted. First, capacity was computed using four recognized designed methods considering the unplugged, plugged, and internally plugged conditions. Next, the calculated capacities were compared to capacities measured (interpreted) from static load tests. Finally, voting was employed to identify plugging based on the closeness of the computed capacity assumptions to the interpreted capacity. Most piles were found to be unplugged. A diameter criterion is proposed as a tool to give early insight into the plugging condition of a pile ahead of driving which resulted in a 70 ± 10% accuracy. The proposed criterion was validated once using a dataset of 23 piles with CPT data and a second time using 24 published driving records where plugging records were available and achieved similar accuracy, in both cases. It was concluded that piles larger than ~0.9 m (36 inches) in diameter have a higher likelihood of being unplugged, while piles smaller than 0.5 m (20 inches) have a higher likelihood of being plugged.

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Section: Discussionmentioning

confidence: 99%

Insights into Plugging of Pipe Piles Based on Pile Dimensions

Kodsy

Iskander

2022

Applied Sciences

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“…The database contains 666 compression static load tests on various pile types that passed initial screening. This number is in addition to 139 and 304 load tests on LDOEPs and drilled shafts, respectively, which are presented in two separate studies ( 6 , 7 ). However, some pile types were underrepresented in the database and thus cannot be counted on to provide statistically significant insights in relation to these pile types.…”

Section: Load Test Databasementioning

confidence: 99%

“…The performance of the NYU criterion was evaluated previously for LDOEPs and for drilled shafts ( 6 , 7 ). In this paper its performance is also evaluated for concrete piles (square and round), pipe piles (open and closed), and for H-piles.…”

Section: Performance Of the Nyu Criterion For Various Pile Typesmentioning

confidence: 99%

“… Note : LDOEPs = large diameter open ended piles; NYCBC = New York City Building Code; na = not applicable. a Data from Kodsy et al ( 6 ). b Data from Kodsy et al ( 7 ). …”

Section: Performance Of the Nyu Criterion For Various Pile Typesmentioning

confidence: 99%

“…The NYU criterion ( 6 ) was developed to meet these conditions. The criterion was originally developed for LDOEPs and was later applied to drilled shafts ( 7 ). The method showed promising performance when compared with some of the most widely used interpretation criteria and was significantly better than many.…”

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confidence: 99%

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Universal Criterion for Interpreting Capacity from Load Tests on Piles

Kodsy¹,

Iskander²,

Pandey

2022

Transportation Research Record: Journal of the Transportation R

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Interpretation of field load tests on piles has many important practical and financial implications in foundation engineering practice. However, identifying the ultimate capacity or resistance on a continuous load settlement curve remains elusive. The geotechnical engineering literature abounds with over 40 criteria to aid in interpreting the ultimate capacity from static load tests on deep foundations. These include settlement, settlement rate, offset, and creep criteria, among others. Since the 1990s criteria proposed by Davisson, AASHTO, and New York City Building Code as well as the 5% and 10% of diameter criteria have evolved to become the most routinely specified for all foundations, without assessing their performance or what they have been intended for. This study provides a side-by-side comparison of the performance of these methods in relation to usability, accuracy, precision, and length and diameter effects. In addition, the performance is also compared with the recently developed NYU criterion where the capacity is taken as the smallest of (i) a settlement corresponding to the elastic compression plus 0.75 in.; (ii) the capacity at plunging or strain-softening; or (iii) settlement corresponding to 5% of the pile diameter, unless the settlement threshold is modified by the structural engineer of record. Assessment is made possible using a database of 350 load tests conducted on square and round concrete piles, open and closed steel pipe piles, as well as H-piles. Comparison suggests that the NYU criterion is the most versatile, precise, and accurate among the examined methods.

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