Erratum for “Reliability-Based Design of Augered Cast-in-Place Piles in Granular Soils” by Armin W. Stuedlein, William J. Neely, and Thomas M. Gurtowski

The authors wish to correct errors in Fig. 4 and Eq. (4), both of which represent the distribution of $\beta \text{-coefficient}$ values. Data derived from the Neely (1991) dataset are referenced as a function of the length of the pile, $L_p$, and are not representative of the midpoint of a soil layer of interest. The correct form of Eq. (4) is expressed in terms of $L_p$For this reason, $\beta \text{-coefficients}$ derived from the new loading tests and the Federal Highway Administration (FHWA) design model are not immediately comparable to the Neely (1991) dataset, and are removed from the corrected Fig. 4 as presented here. [Similar corrections to Eq. (4) and Fig. 6 in Stuedlein and Gurtowski (2012) must be made.]

It is important to note the distinction of the length variable with respect to reliability calculations. Reliability calculations for uplift originally were made with respect to the length of the pile for the new model, and are, therefore, consistent with the significant majority of the $\beta \text{-coefficient}$ data, and with respect to the midpoint of the pile for the FHWA model, as is appropriate. Similarly, capacity calculations for piles in compression were made with respect to the length of the pile, as is appropriate and in accordance with the corrected Eq. (4).

Previously, the bias statistics associated with Eq. (4) as shown in Table 3 and plotted in the previous Fig. 8(b) were equal to 1.10 and 37% for the equivalent normal mean bias and its coefficient of variation ($n=63$). Fig. 8(b) has been revised to Fig. 8(a) with respect to the corrected Eq. (4) and Fig. 4, and compares the normal and lognormal distributions from Table 3 to the new sample bias distribution. Fig. 8(a) indicates that there is no impact to the previously determined continuous resistance bias distributions and, therefore, no impact to the resulting resistance factors for either compression or uplift. Thus, the corrections noted here do not affect any of the results, conclusions, or inferences in the paper.

However, it is anticipated that additions to the $\beta \text{-coefficient}$ dataset resulting from newly reported data could result in changes to the resistance bias distributions, and such changes are both welcome and necessary to best represent possible uncertainty in the reliability-based strength limit design of augered cast-in-place piles.