Two topics of practical significance are discussed : (a) The widely-held perception, reflected in `pMI @"m
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus r[doN{%
can be ignored in design to be on the safe side) is shown to be the result of a misconception 75@!j[QL<
stemming from the shape of current design response acceleration spectra for soft/deep soil baL O~C
conditions. Properly normalising the structural period by a dominant period of motion before ?vmu,y
statistically processing recorded response spectral values, produces completely different shape and SM57bN
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. -^1}J
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic st-
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design of shallow foundations could overcome the strict limitations of the so-called “capacity 0c2O'&$au
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity 9((BOq
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– %bu$t,
nonlinear response may merely lead to acceptable permanent horizontal and rotational i cO$9c
deformations.
