Soil-Structure Interaction Response of Deeply Embedded Structures—The Racking Phenomenon

Soil-structure interaction (SSI) analysis is completed for a relatively rigid, deeply embedded structure. The structure has a large excavated volume, approximately 200’ by 400’ in footprint and 140’ embedded. Eight different site conditions are considered for the analyses providing for a range of soil property types. Results are reported in terms of structural displacements relative to the basemat elevation. In this paper, the conditions that induce a racking type response versus an inertial response are discussed. For certain soil cases, a racking type response is observed where a change is apparent in the profile of relative displacements throughout the embedded height. The racking response indicates a distortional response of the structure as a whole. In other cases, an inertial response is observed where the displacement profile is rather uniform throughout the height of the structure.