Two topics of practical significance are discussed : (a) The widely-held perception, reflected in y@o9~? M
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus QFW0K D`5
can be ignored in design to be on the safe side) is shown to be the result of a misconception <I7(eh6d
stemming from the shape of current design response acceleration spectra for soft/deep soil Sc&)~h}YF
conditions. Properly normalising the structural period by a dominant period of motion before { H=oxa
statistically processing recorded response spectral values, produces completely different shape and 1z~k1usRK
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. ,4H;P/xsb
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic /7k.r}6\R
design of shallow foundations could overcome the strict limitations of the so-called “capacity i1qS ns
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity 8%o~ 4u3
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– Jo{ zy
nonlinear response may merely lead to acceptable permanent horizontal and rotational lo+xo;Nd
deformations.
