Effect of Elastic and Inelastic DSSI on seismic demans of SDOF structures

Abstract

In general, under earthquake loading, the soil reaches the limit of its elastic behavior before the structural elements. Thus, an
earthquake analysis approach assuming inelastic structural behavior under fixed base condition or with elastic dynamic soil-structure
interaction (DSSI) hypothesis may be inadapted. This paper describes the investigation conducted in order to define the contribution
of the pure elastic DSSI effects in the complete inelastic DSSI problem. With this purpose, a comparative analysis between elastic and
inelastic soil behavior assumptions for two inelastic single-degree-of-freedom (SDOF) structures and two soils is carried out. The
results point out that, in general, inelastic soil behavior plays a decisive role only when the soil is saturated. When the soil is in dry
condition, an elastic DSSI approach seems to be accurate enough to take into account the modification of the structural response due
to DSSI. Differences in structural dynamics responses are related to pore pressure generation induced in the inelastic case and
neglected when elastic soil behavior is assumed.