Frequency and intensity dependent dynamic responses of soil-steel pipe sheet pile (SPSP) foundation-superstructure system

Abstract

Frequency and intensity dependent dynamic response behavior of soil-steel pipe sheet pile (SPSP) foundation and superstructure supported on it is studied in this work considering the soil-structure interactions (SSI) effect through experimental investigation by utilizing a physical scaled model of soil-SPSP foundation-superstructure (S-SPSP-S) system. The vertical shear resistance of SPSP foundation joint is assessed experimentally by using an element model of SPSP joint and the result satisfies the requirement laid in design code. The components of sub-structuring solution technique for dynamic response computation namely-the inertial interaction effect and the kinematic interaction effect are estimated through SPSP foundation head loading test and shake table experiment under 1-g conditions, respectively. Frequency and intensity dependent SPSP foundation head impedance functions (IFs) and effective foundation input motion (EFIM) are estimated from these experiments for inertial interaction and kinematic interaction, respectively. The total dynamic response of S-SPSP-S system is computed using the sub-structuring technique through superposition of the experimentally measured IFs and EFIM. The superimposed dynamic response is further compared with the experimental total dynamic response estimated from shaking table experiment with the model S-SPSP-S system. The comparison shows certain discrepancies particularly in resonance behavior of SPSP foundation system. The reason for such observed difference is the stiffness variation of SPSP foundation unit due to the nonlinear behavior of SPSP joint resulting from profound influence of superstructure mass. As a whole, the results and discussions presented in this paper will provide the reader a detail insight on the fundamental dynamic response behavior of S-SPSP-S system.