In this paper, investigations have been performed to study the seismic performance of a Low and Mid-rise steel moment-resisting frame, including 3- and 9-stories buildings with a mat foundation on a soft soil deposit, under the near and far-fault earthquake effects through 2D modeling using the FDM. The above-mentioned frames were analyzed under two different conditions: I) fixed-base (no soil-structure interaction) II) flexible-base (considering soil-structure interaction). The results of the analysis include that the near-field strong ground motions have imposed more critical structural responses compared to far-field records, which indicates the importance of investigating near-filed earthquakes. In addition, due to the near and far fault effects, it is observed that soil structure interaction increases amplitude and stresses when compared to a fixed base.

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