Integration of Pile Set-Up with Calibration of Geotechnical Resistance Factor for Axially Loaded Driven Piles in Cohesive Soil: A Case Study-Paper

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The study presents a reliability-based method for incorporating pile setup into the calibration of geotechnical resistance factors (GRFs) for axially loaded driven piles in cohesive soils. Pile driving generates excess pore-water pressure, temporarily reducing capacity; as this pressure dissipates and soil conditions recover, pile resistance increases over time.<br /><br />The method uses Monte Carlo simulation (MCS) to account separately for resistance at end of drive (EOD) and the additional resistance from setup, rather than treating the beginning-of-restrike (BOR) capacity as a single uncertain resistance. The approach was applied to a Winnipeg case study using 45 PDA tests: 18 at EOD and 27 at BOR. Predicted capacities were estimated using the α-method, and setup was modeled with the Skov–Denver relationship.<br /><br />For a target reliability index of 2.33, the calibrated GRFs were 0.625 for EOD resistance, 0.269 for setup resistance, and 0.495 for total BOR resistance. Applying separate factors to EOD and setup produced higher factored pile resistance than using one factor for BOR capacity. This could reduce the required number or length of piles and lower project costs.<br /><br />The authors conclude that the method can integrate setup effects into LRFD design while accounting for uncertainty in each resistance component. However, the findings are based on one case study and should be validated with additional field data, including PDA and static load tests across a wider range of geotechnical conditions.

Keywords

pile setup

geotechnical resistance factors

driven piles

cohesive soils

Monte Carlo simulation

end of drive

beginning of restrike

Skov-Denver relationship

α-method

load and resistance factor design