Chapter 6: Analysis of soils and soil–structure interaction

Seismic loading is unique in that the medium (i.e. the soil) which imposes the loading on a structure also provides it with support.

The designer of earthquake-resistant structures needs some understanding of how soils respond during an earthquake; not only is this important for the foundation design itself (covered in Chapter 7), but the nature of soil overlaying bedrock has a crucial modifying influence on the seismic hazards posed by the site.

This chapter covers

The response of soils to earthquake excitation is highly complex and depends on a large range of factors, many of which cannot be established with any certainty. The discussion that follows is intended to highlight the important features that apply to the most standard cases; often, specialist geotechnical expertise will be needed to resolve design issues encountered in practice. A more complete discussion of the parameters that affect soil response is provided by Pappin (1991) and Kramer (1996).