Elastic Response of Soil-Structure Systems Subjected to Near-Fault Rupture Directivity Pulses

Generally, in order to evaluate the seismic demand of structures, it is assumed that the structure is located on a rigid soil, with increasing the soil flexibility, there will be significant variations in the structural response, i.e. the effects of Soil-Structure Interaction (SSI). Additionally, ground motions close to active faults have some important characteristics that make them to be different from those recorded in far-fault regions. Forward rupture-directivity velocity pulses, high-frequency acceleration records, and permanent displacement, are notable specifications of records close to ruptured faults. Among mentioned characteristics, forward rupture-directivity effect causes velocity pulses that could potentially exert great damages to buildings in near-fault regions. These pulses possess statistical certainty; hence, researchers tried to present synthetic models for them. In this paper, a parametric study is carried out on the elastic response of soil-structure systems having shallow foundations subjected to a pulse-type motion and near-fault records in order to develop a systematic procedure for assessing near-fault and SSI effects on design of structures. It is concluded that under SSI effects there are clear similarities between elastic demands subjected to pulse-type, and near-fault motions. Consequently, the final form of relationship as a representation of near-fault characterizations under SSI effects is presented.