Spatial Variation of Earthquake Ground Motion (SVEGM) is clearly indicated in data recorded at dense seismographic arrays

The main purpose of this paper is to study the influence of SVEGM on the seismic response of large embankment dams. To this

end, the Masjed Soleyman embankment dam, constructed in Iran is selected as a numerical example. The spatially varying ground

motion time histories are generated using spectral representation method. According to this methodology, the generated time

histories are compatible with prescribed response spectra and reflect the wave passage and loss of coherence effects. To

investigate the sensitivity of the dam responses to the degree of incoherency, three different coherency models are used to simulate

spatially variable seismic ground motions. Finally, the seismic response of the dam under multi-support excitation is analyzed

and compared to that due to uniform ground motion. Also, the Newmark's method is used to estimate seismic-induced permanent

displacements of the embankment dam. The analysis results reveal that the dam responses can be sensitive to the assumed spatial

variation of ground motion along its base. As a general trend, it is concluded that the use of multi-support excitation, which is

more realistic assumption, results in lower acceleration and displacement responses than those due to uniform excitation.

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.