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

PPT Presentation

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The study compared the dynamic behavior of a six-storey building supported by a 2×2 pile group with that of an equivalent lumped-mass model and a rigid-base building. Tests were conducted on a one-degree-of-freedom shaking table using Jumunjin sand at two densities, with sinusoidal sweep tests and shaking inputs of varying acceleration. The research focused on how soil–structure interaction (SSI) affects natural frequency, damping, acceleration response, and base shear.<br /><br />The results showed that the lumped-mass model and the soil–pile–building system had different natural frequencies, while the rigid-base assumption did not adequately represent the behavior of the actual foundation–building system. Base shear was greatest for the rigid-base system, followed by the soil–pile–building system and then the lumped-mass model; the lumped-mass model’s base shear increased relative to the building system as input acceleration rose. Acceleration-response rankings also depended on input level: at lower acceleration, the lumped-mass system responded most strongly, whereas at higher acceleration, the soil–pile–building system did. Damping was strongly influenced by soil conditions and foundation effects, but was rarely affected by the number of building storeys.<br /><br />Overall, the findings highlight the importance of accounting for soil and foundation flexibility when evaluating seismic response. Neither a rigid base nor a simplified lumped-mass representation necessarily captures the dynamic behavior of a pile-supported building.

Keywords

soil-structure interaction

SSI

pile group

shaking table test

dynamic behavior

natural frequency

damping

base shear

seismic response

foundation flexibility