Soil–Structure Interaction (SSI) for Building Structures

Soil–Structure Interaction (SSI) is one of the most important yet often overlooked aspects of earthquake engineering. Many structural analyses assume buildings rest on a rigid, fixed base—but in reality, soil flexibility significantly alters structural response during earthquakes.

This course introduces the fundamentals of SSI in a clear, step-by-step manner, based primarily on two authoritative references:

• FEMA P-2091: A Practical Guide to Soil–Structure Interaction (2020)

• NIST GCR 12-917-21: Soil–Structure Interaction for Building Structures

The course begins with the basics of soil and structural dynamics, develops the principles of SSI, and then demonstrates how to incorporate these effects in practical building analysis using ETABS. By the end, you will be able to confidently model and interpret SSI effects for buildings with raft foundations under earthquake loading.

After completing the course, students will:

• Have a strong conceptual foundation in soil–structure interaction.

• Be able to apply FEMA and NIST simplified methods to real buildings.

• Confidently build SSI-influenced models in ETABS for multi-story buildings with raft foundations.

• Interpret SSI results and make informed engineering decisions about their significance.

Course Requirements

• Basic knowledge of structural engineering and earthquake engineering is essential.

• Familiarity with ETABS software at a beginner level is required.

• No prior experience with soil–structure interaction is required.