Gx. Wu et Wdl. Finn, DYNAMIC NONLINEAR-ANALYSIS OF PILE FOUNDATIONS USING FINITE-ELEMENT METHOD IN THE TIME-DOMAIN, Canadian geotechnical journal, 34(1), 1997, pp. 44-52
A quasi-three-dimensional method of analysis is presented for the nonl
inear dynamic analysis of single piles and pile groups. The analysis i
s performed in the time domain using strain-dependent moduli and dampi
ng, yielding at failure, and a no-tension cutoff. The analysis has bee
n incorporated into the computer program PILE-3D and has been validate
d using data from centrifuge tests on a single pile and a 2 x 2 pile g
roup under simulated earthquake loading. Analyses of the centrifuge te
sts demonstrated a significant reduction in soil moduli around the pil
es during strong shaking and a corresponding reduction in pile stiffne
sses. The time-dependent shear modulus distribution in soil around the
pile is obtained as part of the output. This allows the time variatio
n of dynamic impedances of pile foundations during shaking to be estab
lished and allows a realistic assessment of the single-valued stiffnes
ses and damping factors usually incorporated into commercial structura
l analysis programs for the seismic analysis of pile-supported structu
res. The analysis also demonstrates the importance of inertial interac
tion between foundation and structure.