Two topics of practical significance are discussed : (a) The widely-held perception, reflected in P]+^^ U
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus ZzI^*Nyg
can be ignored in design to be on the safe side) is shown to be the result of a misconception ")HTUlcAe}
stemming from the shape of current design response acceleration spectra for soft/deep soil )G
,LG0"-
conditions. Properly normalising the structural period by a dominant period of motion before g i:;{
statistically processing recorded response spectral values, produces completely different shape and -z0,IYG }
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. W #qM$
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic f9JD _hhP'
design of shallow foundations could overcome the strict limitations of the so-called “capacity K;-:C9@
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity /k1&?e
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– V:!fe+ Er
nonlinear response may merely lead to acceptable permanent horizontal and rotational N{P (ym2yR
deformations.
