Two topics of practical significance are discussed : (a) The widely-held perception, reflected in SB g |V
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus r3 dGXiu
can be ignored in design to be on the safe side) is shown to be the result of a misconception `(M0I!t
stemming from the shape of current design response acceleration spectra for soft/deep soil 0i(c XB
conditions. Properly normalising the structural period by a dominant period of motion before Sq]QRI/
statistically processing recorded response spectral values, produces completely different shape and -tA_"q'^
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. YySo%\d
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic S]Ye`
design of shallow foundations could overcome the strict limitations of the so-called “capacity 6&o?#l;|
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity oSLm?Lu
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– uyvjo)T
nonlinear response may merely lead to acceptable permanent horizontal and rotational D2I |Z
deformations.
