Two topics of practical significance are discussed : (a) The widely-held perception, reflected in ( -@I'CFd
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus =<AG}by![
can be ignored in design to be on the safe side) is shown to be the result of a misconception R{6 M(!x
stemming from the shape of current design response acceleration spectra for soft/deep soil hE'>8 {
conditions. Properly normalising the structural period by a dominant period of motion before h dqr~9
statistically processing recorded response spectral values, produces completely different shape and ?.c:k;j
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. db>"2EE
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic >x
]{c b/m
design of shallow foundations could overcome the strict limitations of the so-called “capacity klTRuU (
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity U }l= 1B
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– S8C} C#
nonlinear response may merely lead to acceptable permanent horizontal and rotational Jn9 {@??
deformations.
