Two topics of practical significance are discussed : (a) The widely-held perception, reflected in Ll=G+cw6P
most seismic codes, that soil-structure interaction (SSI) plays invariably a beneficial role ( and thus W~mo*EJ'^
can be ignored in design to be on the safe side) is shown to be the result of a misconception t[q2 W"#.
stemming from the shape of current design response acceleration spectra for soft/deep soil G K~A,Miqk
conditions. Properly normalising the structural period by a dominant period of motion before t}R!i-D|HB
statistically processing recorded response spectral values, produces completely different shape and -
2L(])t6
size of spectral ordinates ; thus an increased period due to SSI may lead to higher response. @]n8*n
(b) Analytical, experimental and field evidence in recent years has started revealing that seismic (@} ^ 3jpT
design of shallow foundations could overcome the strict limitations of the so-called “capacity q.=Q
design”, by allowing significant sliding, uplifting, and even mobilisation of bearing–capacity @FIL4sb
failure mechanisms to occur. It is shown that under seismic conditions such dynamic inelastic– ^)9/Wz _x
nonlinear response may merely lead to acceptable permanent horizontal and rotational iO*5ClB
deformations.
