Browsing by Author "Al-dayyeni, Nawaf Hani Muslim"
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Item A STUDY ON MODELING SOIL-STRUCTURE INTERACTION EFFECTS IN BUILDINGS(2022-02-14) Al-dayyeni, Nawaf Hani Muslim; Sönmez, ErtanSoil-structure interaction is usually not considered in the design of most buildings in civil engineering practice. Based on the assumption that these effects reduce the base shear (and the overall earthquake load) for most building structures and soil conditions due to period lengthening, omission of soil-structure effects is in general considered to be conservative and the buildings are designed as fixed base structures. This assumption does not hold for certain building structures and soil conditions (e.g., massive structures, tall buildings, and structures on soft soil). In this thesis, soil-structure interaction effects in buildings are studied using relatively simple models prepared by a general-purpose structural analysis software (SAP2000). A symmetrical, 6-story, 6-bay reinforced concrete moment resisting frame is considered for both two-dimensional (2D) and three-dimensional (3D) building models. Seismic responses of three different building structures (with varying dynamic characteristics) on three different homogeneous, elastic soil mediums are computed and compared with the responses of the corresponding fixed base models. Soil-structure interaction effects are modeled by two approaches: (i) using soil springs representing the soil impedance functions (substructure method), and (ii) modeling the soil medium directly along with the structure and the foundation (direct analysis method). Two types of foundation are considered in the models: footing foundation (i.e., isolated footings) and raft foundation. ASCE 7-10 acceleration response spectra are determined based on the soil properties and used to examine the seismic response of the models considered. A limited study is also performed by time-history analyses using an actual earthquake ground acceleration record (1940 El Centro). Analyses of 2D and 3D models showed the well-known period lengthening effect of soil-structure interaction clearly. The results of this study indicate that spring models based on soil impedance functions that are widely used in practice lead to a lesser period lengthening effect compared to direct models. Similarly, by examining the base shear, story displacement, story drift, and foundation settlement results, it is observed that the soil-structure interaction effects were more significant in the direct models compared to the spring models.