assessment of near-field and far-field strong ground motion effects on soil-structure sdof system

The distinctive characteristics of near-field earthquake records can lead to different structural responses from those experienced in far-field ones. furthermore, soil-structure interaction (ssi) can have a crucial influence on the seismic response of structures founded on soft soils; however, in most of the time has been neglected nonchalantly. this paper addresses the effects of near-field versus far-field earthquakes on the seismic response of single degree of freedom (sdof) system with considering ssi. a total 71 records were selected in which near-field ground motions have been classified into two categories: first, records with a strong velocity pulse, (i.e. forward-directivity); second, records with a residual ground displacement (i.e. fling-step). findings from the study reveal that pulse-type near-field records generally produce greater seismic responses than far-field motions especially at high structure-to-soil stiffness ratios. moreover, the importance of considering ssi effects in design of structures is investigated through an example. finally, parametric study between peak ground velocity to peak ground acceleration ratio (pgv/pga) of pulse-like ground motions and maximum relative displacement indicate that with increase in structure-to-soil stiffness ratios, earthquakes with higher pgv/pga ratio produce greater responses.