Horizontal dynamic stiffness and interaction factors of inclined piles

A Timoshenko beam-on-Pasternak foundation (T-P) model was developed to estimate the horizontal dynamic impedance and interaction factors for inclined piles subjected to horizontal harmonic load. The inclined pile with a fixed pile-to-cap connection was modeled as Timoshenko beams embedded in the homogeneous Pasternak foundation. The reactions of the soil on the pile tip were simulated by three springs in parallel with corresponding dashpots. The differential equations of normal and axial vibrations of the inclined pile were solved by means of the initial parameter method. The model and the theoretical derivations were validated through comparisons with results from other theoretical models for some large-diameter end-bearing piles and inclined piles. The effects of shear deformations of the soil and inclined piles, during the vibration, were highlighted by comparing the results of the T-P model with those from Euler beam-on-dynamic-Winkler foundation (E-W) model. Findings indicated that the T-P model is more accurate than the E-W model for analyzing the dynamic performance of the inclined piles with small slenderness ratios and large inclined angles. The effects of the inclined angle, slenderness ratio, and distance-diameter ratio on the dynamic impedance and interaction factors were studied by numerical examples. It is shown that the increased angle of the pile results in an increase of horizontal impedance and decreases in interaction factors.