The Effect of Soil-Structure Interaction on Seismic Response of R A Study on Einforced Concrete Buildings Supported on Pile Foundations

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Addis Ababa University


In this study, the effects of soil-foundation-structure interaction effects are investigated for five reinforced concrete building structural models supported on pile foundations. The building models are assumed to be regular both in geometry and stiffness to avoid unnecessary complications due to torsion. The study is conducted using the sub structure method of soil-foundation-structure interaction analysis which idealizes the superstructure to be supported by springs and dashpots. The spring and dashpot coefficients, which respectively represent the stiffness and damping of the foundation system, are obtained from the dynamic impedance functions. Using SAP structural analysis software the flexible-base and fixed-base building models are analyzed and differences in their seismic responses systematically compared. Base shears, overturning moments, bending moments and shear forces along selected beams, axial forces in selected columns, bending moments in shear walls are the main parameters used to compare the analyses results of the flexible-base and fixed-base models to assess the influence of soil flexibility. In this study it is observed that the seismic responses of buildings supported on pile foundations are influenced when the effects of soil-structure interaction are considered. In most of the cases considering soil-structure interaction results in lower seismic responses which is an economic advantage. However, it should be stated that in some cases higher seismic responses of buildings are observed. The seismic responses of buildings supported on pile foundations are observed to depend mainly on soil type, bearing mechanism of piles, and height of buildings when the effects of soil-structure interaction are considered. Key words: Seismic Soil-Pile-Structure Interaction (SSPSI), dynamic impedance function, flexible-base model, fixed-base model.



Words: Seismic Soil-Pile-Structure Interaction (SSPSI);Dynamic Impedance Function; Flexible-Base Model; Fixed-Base Model