Two topics of practical significance are discussed : (a) The widely-held perception, reflected in eXYR/j<8
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus <
5ow81
can be ignored in design to be on the safe side) is shown to be the result of a misconception G9
!1Wzs
stemming from the shape of current design response acceleration spectra for soft/deep soil )JP cSy*
conditions. Properly normalising the structural period by a dominant period of motion before S(Pal/-"
statistically processing recorded response spectral values, produces completely different shape and "elh~K
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. ~4M]SX1z
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic Q|>y2g!
design of shallow foundations could overcome the strict limitations of the so-called “capacity &e(de$}xt
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity D"MN lm
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– 7;XdTx
nonlinear response may merely lead to acceptable permanent horizontal and rotational __QT lj
deformations.
