Comparison Analysis of pile-supported lumped mass and actual buildings under dynamic loadings-Paper

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The study used 1g shaking-table sweep tests to compare the dynamic response of pile-supported lumped-mass systems with six-story building models in loose and dense Jumunjin sand. Tests varied input acceleration from 0.05g to 0.3g and examined resonant frequency, damping, and pile response.<br /><br />The results reported in the main analysis show that lumped-mass systems had higher resonant frequencies than the six-story buildings, regardless of soil density. Resonant frequencies generally decreased as input acceleration increased, with the building models showing greater sensitivity at lower acceleration levels. The authors attribute differences partly to the buildings’ higher centers of mass and larger horizontal displacements. The response spectra also showed that the number of detectable resonant modes depended on soil density and the test frequency range.<br /><br />Damping depended on soil and foundation conditions. Dense sand produced lower damping ratios than loose sand, consistent with greater energy dissipation in softer soil. Damping ratios were broadly similar between lumped-mass and soil–pile–structure systems, and the lumped-mass results changed relatively little with soil density. The abstract also reports that pile bending moments in lumped-mass systems were smaller than in building systems as input acceleration increased.<br /><br />Overall, the findings highlight that simplified structural representations may not reproduce the dynamic behavior of actual soil–pile–building systems. The study emphasizes the importance of accounting for soil–foundation–structure interaction in seismic analysis.

Keywords

shake-table test

pile-supported system

lumped-mass model

six-story building

Jumunjin sand

resonant frequency

damping ratio

soil-structure interaction

pile bending moment

dynamic response