Assessment of Soil-Pile-Structure Interaction Influencing Earthquake Response of Building in Layered Soils

Abstract

Pile foundations are the deep foundations provided for the structures resting on soft or weak soil. The pile foundation design is done in such a way that it should withstand the structural loads along with seismic forces. The process in which response of the soil influences the motion of the structure and the motion of the structure influences the response of the soil is known as soil-structure-interaction. Neglecting the effect of SSI leads to the unsafe design for the structures resting on weak soil. In the present study the behaviour of the building with SSI interaction under the action of seismic forces is undertaken using SAP2000 software. When the seismic waves travel through different soil profiles, there is an alteration in the earthquake waves due to the variation of soil properties. The deep soil software is used to model the ground response. The earthquake data at the surface level and at the bedrock level from the DEEPSOIL is used to study the dynamic behaviour of the structure with fixed base condition and with SSPSI condition under the action of vertical and lateral load through time history analysis using SAP2000. The input earthquakes considered in the present work are Chi-Chi, Kobe and Imperial valley. The two different conditions were considered and it includes three layers of soil (SCS-NEVADA-SCS) with end bearing pile and three layers of soil (SCS-NEVADA-SCS) with floating piles. The results include that the PGA (Peak Ground Acceleration) at the surface level is reduced compared with the bedrock data because of the liquefaction. In SSPSI model there is a maximum displacement and inter-storey drift values compared to fixed base model which are unsafe in condition and leads to failure of the building. The mode shapes of both SSPSI model and fixed base model were shown. The bending moment and shear force in SSPSI model increases compared to fixed base model. Acceleration amplification ratio for Kobe earthquake is maximum compared to other two earthquakes. In SSPSI model, floating pile foundation contributes for lesser displacement and inter-storey drift of structure compared to end-bearing pile foundation.