Effect of extrapolation on interpreted capacity and model statistics of steel H-piles

ABSTRACT

For steel H-piles under axial compression, 177 static load tests were used to evaluate the performance of the Chin-Davisson method to (1) interpret pile capacity and (2) characterise the statistics of the model factor, defined as the ratio between the interpreted capacity and the value calculated by the static design methods in ISO 19901-4:2016. The measured curve for each case history was artificially truncated at the maximum applied load equal to 50%, 75%, and 90% of the capacity defined by the Davisson method. The Chin-Davisson method was then applied to the truncated curve to interpret the capacity. The results indicate that the (1) hyperbolic extrapolation will over-predict the pile capacity and result in more uncertainty, (2) bias of the Chin-Davisson method is greater than that of the Davisson method and decreases as the maximum applied load approaches the actual Davisson capacity, and (3) extrapolation from load test terminated at 75% or higher of the actual Davisson capacity is reasonable.

KEYWORDS:

• Static load test database
• Davisson offset limit
• Chin extrapolation
• model statistics
• steel H-pile

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Kok-Kwang Phoon http://orcid.org/0000-0003-2577-8639