عنوان مقاله [English]
In this study, the effect of near-field ground motions pulses on the seismic response of a soil−pile-structure system is investigated. The forward directivity effect, which includes a large velocity pulse at the beginning of the velocity time history of the ground motion, is the most damaging phenomenon observed in near-field ground motions. This large amplitude medium- to long-period pulse contains most of the seismic energy from the rupture. To investigate the effect of near-field ground motions on the seismic response of a soil-pile-structure system, a three-dimensional model, consisting of the soil, pile group and the structure is used. Modeling is performed by using the ABAQUS software. The Von Wolffersdorff hypoplastic model considering the intergranular strain concept is applied for modeling of cohesionless soil (sand), and the behavior of structure is considered to be non-linear. Eight fault-normal near-field ground motion records, which were recorded on rock, are applied to the model. The results show that near-field velocity pulses have a considerable effect on the behavior of the system, and cause sudden large displacement demands on the structure and piles. Therefore, the structure undergoes large non-linear deformations, and the fundamental period of the structure elongates. It should be noted that when the elongated period of the structure is near the period of the velocity pulse, the severity of non-linear deformation increases. In addition, there are positive correlations between the PGV and PGD values of the ground motion records, and the deformation demands on the piles.