Numerical Analysis of the Soil-Pile-Structure Interaction on Structure's Base Shear-Paper

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The study examines how soil–pile–structure interaction affects ground-motion amplification and, consequently, structural base shear—effects not explicitly represented in common seismic design procedures.<br /><br />Researchers first conducted shaking-table tests on a scaled piled-raft structure in dry sand. They then built a three-dimensional ABAQUS model of the test setup and compared its results with measured accelerations. The agreement in acceleration trends and magnitudes was considered adequate to support a broader numerical parametric study.<br /><br />The numerical study compared four foundation configurations: a raft without piles, and rafts supported by one, four, or nine piles. Each configuration was subjected to gradual sinusoidal loading at seven frequencies, from 5 to 20 Hz, with peak acceleration up to 0.35 g. The authors assessed cap acceleration amplification relative to the pile-free raft as an indicator of the piles’ influence on base shear.<br /><br />Results show that pile presence and pile-group size can substantially affect acceleration amplification. However, adding piles does not consistently reduce amplification or base shear. At a given pile count, responses also do not change monotonically with loading frequency. The findings indicate that foundation and pile effects should be considered when estimating seismic demand, and that their influence depends on both pile configuration and the frequency of the input motion.

Keywords

soil-pile-structure interaction

ground-motion amplification

base shear

shaking-table tests

piled-raft foundation

ABAQUS model

seismic response

pile group effects

acceleration amplification

foundation dynamics