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Structural Engineering and Mechanics
  Volume 66, Number 5, June10 2018 , pages 637-648
DOI: https://doi.org/10.12989/sem.2018.66.5.637
 


Effects of foundation flexibility on seismic demands of asymmetric buildings subject to near-fault ground motions
Gholam Reza Atefatdoost, Behtash JavidSharifi and Hamzeh Shakib

 
Abstract
    When the centers of mass and stiffness of a building do not coincide, the structure experiences torsional responses. Such systems can consist of the underlying soil and the super-structure. The underlying soil may modify the earthquake input motion and change structural responses. Specific effects of the input motion shall also not be ignored. In this study, seismic demands of asymmetric buildings considering soil-structure interaction (SSI) under near-fault ground motions are evaluated. The building is modeled as an idealized single-story structure. The soil beneath the building is modeled by non-linear finite elements in the two states of loose and dense sands both compared with the fixed-base state. The infinite boundary conditions are modelled using viscous boundary elements. The effects of traditional and yield displacement-based (YDB) approaches of strength and stiffness distributions are considered on seismic demands. In the YDB approach, the stiffness considered in seismic design depends on the strength. The results show that the decrease in the base shear considering soft soil induced SSI when the YDB approach is assumed results only in the center of rigidity to control torsional responses. However, for fixed-base structures and those on dense soils both centers of strength and rigidity are controlling.
 
Key Words
    torsional response; yield displacement-based approach; dynamic soil-structure interaction; strength distribution; stiffness and strength eccentricity
 
Address
Gholam Reza Atefatdoost: Department of Civil Engineering, Estahban Branch, Islamic Azad University, Estahban, Iran
Behtash JavidSharifi: Fars Regional Electrical Company, Shiraz, Iran
Hamzeh Shakib: Tarbiat Modares University, Tehran, Iran
 

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