Calibrating Resistance Factor and Factor of Safety of Driven Piles Considering Set-up Effects

Abstract

The ultimate bearing capacity of the driven piles is mainly composed of the ultimate shaft resistance and the ultimate base resistance. The frequent appearance of the set-up effects of the driven piles will be conductive to the improvement of the ultimate shaft resistance after pile driving. The fundamental purpose of this paper is to study the influence of the set-up effects on the design resistance factor and the factor of safety (FS) of the driven piles based on the load and resistance factor design (LRFD) criteria. The set-up effects factor \( \left( \alpha \right) \) and the ratio \( \left( \varepsilon \right) \) of the initial ultimate shaft resistance to the initial ultimate bearing capacity are used to calibrate the formulas for estimating the resistance factor and FS of the driven piles. Meanwhile, the influence of the factor α and the ratio e on the design resistance factor and FS of the driven piles are studied. Analysis indicates that the smaller design resistance factor will be determined for the driven piles with the stronger set-up effects, and so it is for the larger e. And the smaller FS will be estimated for the driven piles with the stronger set-up effects, and so it is for the larger e. However, analysis also demonstrates that the design resistance factor and the estimation FS are nearly not influenced by the factor α and the ratio e when they are larger than the certain values.