Two topics of practical significance are discussed : (a) The widely-held perception, reflected in !Sfe{/$w
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus @?M; 'xMbB
can be ignored in design to be on the safe side) is shown to be the result of a misconception
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stemming from the shape of current design response acceleration spectra for soft/deep soil o@',YF>OQ
conditions. Properly normalising the structural period by a dominant period of motion before QX+Y(P`vMK
statistically processing recorded response spectral values, produces completely different shape and s
kY0 \V
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. 'A1E^rl]=
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic (zEYpTp
design of shallow foundations could overcome the strict limitations of the so-called “capacity *vD/(&pQ1:
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity |rFJ*.nD
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– k!vHO
nonlinear response may merely lead to acceptable permanent horizontal and rotational i&pMF O
deformations.
