Embedment effects of flexible foundations on control of structures

In the design of controller for earthquake-excited building benchmark, it is common to inquire about the present relationships between controlled building performance and the considering soil–foundation–structure interaction (SFSI) effects for description of the earthquake excitation. The SFSI effects can drastically affect the response of the structures subjected to earthquake motion. The effects of embedment depth on the control of structures, under plane-strain conditions, have been studied by substructure approach for buildings supported by rigid foundations embedded into a homogeneous, isotropic and elastic half-space. It is assumed that control devices are installed on all the floors. It is concluded that deeply embedded structures may increase the energy dissipated by control devices for the case of considering SFSI effects than expected from the fixed-base model and decrease the H2 norm of the system transfer function than control of structures with surface supported foundations. The effects are intensified for structures located on relatively soft soils. The inter-story drifts for control of squat structures with embedded foundations may reduce than the one controlled according to the fixed-base model, while it may increase the demand of inter-story drifts for the case of control of slender interacting systems. According to these results, considering SFSI effects on structural control can make some unexpected damages. Hence, for structures rested in or on soft soil that are controlled by active or semi-active control devices, SFSI effects in controller design should be considered.