Soil-structure interactions of piled buildings on ground subject to liquefaction and lateral displacements

Abstract

The lateral design of piled foundations for buildings in liquefiable ground is challenging because of potential reduced lateral support and possible lateral ground displacements. Soil-structure interaction (SSI) analysis is an iterative process and requires effective communication between structural and geotechnical engineers. This paper presents the details of how this process was implemented for a building located on Wellington’s reclaimed waterfront. Understanding the potential for lateral spread and assessing how lateral spread could vary across the building footprint is important as lateral stretch of a building is very damaging. Different design scenarios representing the ground and structure behaviour at different stages of earthquake shaking need to be considered. The process generally comprises the geotechnical engineer providing geotechnical information required for the structural analyses such as soil springs range and any soil loadings on the structure (e.g. passive pressure pushing on the sub-structure). The structural engineer, after performing their analyses, provide information (e.g. base shear loads, pile stiffnesses, fixity, moment capacities etc.) to the geotechnical engineer to carry out an independent analysis. Discrepancies in the analyses must be discussed and investigated. The process is then iterated such that similar pile actions are obtained from both the geotechnical and structural engineer.