B-Spline impulse response functions (BIRF) for transient SSI analysis of pile foundations: Developments and implementation

• Published in: Soil dynamics and earthquake engineering (1984) 2024-07, Vol.182, p.108727, Article 108727
• Main Authors: Ozegbe, Kingsley C., Rizos, Dimitrios C.
• Format: Article
• Language: English
• Subjects: B-spline impulse response; Dynamic soil–structure interaction; Laterally loaded pile foundations; Natural frequency ratio; Simplified models
• ISSN: 0267-7261
• DOI: 10.1016/j.soildyn.2024.108727

The advent and consequential advancements in geotechnical earthquake engineering have made soil–structure interaction analysis (SSI) an important component in the analysis and design of earthquake-resistant structures. The filtering effects of pile foundations which reduce the seismic demand on pile-supported superstructures when subjected to seismic waves, have been investigated and confirmed by several researchers in the last 40 years. To this end, several methods of analyzing the effects of SSI have been developed over the years. From the simplified Winkler model to the more robust finite element method (FEM) and boundary element method (BEM), researchers and structural engineers alike have sought to address the SSI phenomenon. The results produced by such analysis have either been computationally expensive, thereby prohibiting more routine application, as is with the case of the FEM and BEM or the results are outside the scope of more complex structures that they cannot be relied upon, as is with the case of analytical methods that depend on the simplified lumped parameter models or Winkler model. Therefore, there is a need for a solution technique that strikes a balance between simplicity and computational cost without sacrificing accuracy. This work presents a simple, yet accurate model of a pile foundation-soil system for the dynamic analysis of structures, including SSI effects. The simple model is based on solutions that reproduce the characteristic B-spline impulse response functions (BIRF) of 3D continuous soil–pile foundation systems, as obtained from the FEM analysis. The proposed simple model is used within the B-spline impulse response techniques framework and can be coupled directly to other commonly used time domain solutions. •The B-Spline Impulse Response Functions (BIRF) are characteristic system responses in time domain that are independent of external excitations.•BIRFs significantly reduce the size of the soil–pile model to the degrees of freedom coupled with the superstructure.•BIRFs for pile foundations replace the soil–pile substructure in a structure-pile foundation dynamic interaction model.•The proposed BIRFs are as accurate as the rigorous soil–pile foundation models.•The proposed BIRFs can be superimposed directly to structural models for rapid dynamic SSI analysis.