جستجوی مقالات مرتبط با کلیدواژه « Foundation flexibility » در نشریات گروه « فنی و مهندسی »

In this study, the seismic performance of a 20-storey steel structure with a mat foundation located on layered soil is investigated under an array of strong ground excitations, which includes 6 far-fault and 6 near-fault earthquakes. Eight different modes for soil layering have been considered in the numerical simulation. FLAC 2D nonlinear platform has been used to model the near-realistic behavior. To this end, hundred lines of codes and sub-routines have been developed in this platform to perform the analysis. The results of the analyzes include the absolute displacement of the floors, the ratio of the relative displacement of the floors, the shear force, the axial force, and the bending moment of the columns. It was concluded that for a 20-story structure on a mat foundation under both far-field and near-field earthquakes, the most reliable type of soil is the dense sandy soil and the most critical case is the soft clay soil. It was also observed that the near-field strong ground motions have imposed more critical structural responses compared to far-field records.

There are varieties of techniques for calculating natural frequency of the structures. Nevertheless, these equations are less developed in the geotechnical structures such as slopes, buttress group, dams, and retaining walls. In earth dams, with respecting to the dimensions and weight of dam, soil-structure interaction is of prime importance for finding seismic parameters including natural frequency, deformation, and other parameters. To accomplish this objective and the inclusion of foundation flexibility, dam foundation was simulated using transition spring. in this research an equation is presented for calculating natural frequency of earth dam using analytical methods. The advantages of this method include more accurate estimation of seismic parameters as well as considering the flexibility of earth dam's foundation. Riley approximation method and shear-free shape function were used in the mathematical solution steps and the trend of gaining the proposed equation. Finally, the results obtained from the proposed equation were compared to those of finite element software GeoStudio-2007[9] and the correlation of responses was observed.