Near-fault effects on strength reduction factors of soil-MDOF structure systems

Consequences of near-fault ground motions to strength reduction factors of flexible-base multi-story structures are addressed by employing synthetic pulses. For this purpose, three non-dimensional parameters are adopted as the key parameters of interacting systems: (1) non-dimensional frequency as the structure-to-soil stiffness ratio, (2) aspect ratio of the superstructure and (3) structural ductility. The soil and superstructure are idealized as homogeneous elastic half space (Cone model concept) and nonlinear shear building, respectively. A deep sensitivity analysis is carried out to elucidate the impacts of various parameters on strength reduction factors of multi-degree-of-freedom (MDOF) structures considering Soil–Structure Interaction (SSI) effects. It is confirmed that pulse period extremely affects the trend of strength reduction factors while interacting parameters influence this trend at various pulse periods. Moreover, findings of this study demonstrate that amplification factors of equivalent flexible-base single-degree-of-freedom (SDOF) structure are highly impressed due to pulse period effects and interacting factors impose great changes to variations of amplification factors with respect to pulse periods.