The state of practice in soil-structure interaction modelling in New Zealand


  • Theo Hnat University of Canterbury
  • Christopher McGann University of Canterbury
  • Liam Wotherspoon University of Auckland



The current state of practice in soil-structure interaction (SSI) modelling in New Zealand was investigated through an industry-wide questionnaire. This used a mixed methods, sequential explanatory research design involving the collection of quantitative and qualitative questionnaire data, as well as follow-up focus groups. Several statistically significant relationships were observed for SSI modelling approaches between different engineering fields, company sizes, and years of experience.

The key findings from this study suggest that there is no consensus on the best SSI analysis methods, modelling strategies, or guidelines to be used. Overall, fixed base analysis remains the most popular method across all company sizes and number of years of industry experience. Engineers from large companies reported higher consideration for SSI modelling and use of performance-based design for design projects, which perhaps reflects the scale and complexity of projects carried out in those companies. However when SSI is considered, analyses are typically limited to nonlinear vertical springs under the foundation as part of a dynamic analysis. Use of SSI for buildings is typically limited to seismic assessments and complex or otherwise high importance structures. However, bridge engineers routinely used pushover analyses with linear and nonlinear springs and dynamic analyses with nonlinear springs, in contrast with the rest of the industry.

There is further room to improve on the quality of communication and interaction between structural and geotechnical engineers. A lack of specific guidance on when SSI should be considered was reported, alongside broader training issues to ensure that structural and geotechnical engineers fundamentally understand the requirements and input/output needs of each role.


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How to Cite

Hnat, T., McGann, C., & Wotherspoon, L. (2023). The state of practice in soil-structure interaction modelling in New Zealand. Bulletin of the New Zealand Society for Earthquake Engineering, 56(3), 169–185.