عنوان مقاله [English]
Shallow foundations are among the most common types of foundations used to support mid-rise buildings in areas with high seismic hazard. Recent studies have indicated that dynamic interaction of soil-foundation and building can affect the seismic response of structures during an earthquake. Therefore, the foundation features can also change the dynamic characteristics, such as natural frequency and damping of the soil-foundation-structure system. In this research, a 14 story moment resistant frame building built on shallow foundations with various dimensions has been considered and the three dimensional prototype of all three components of soil-foundation-structure system has been modeled by ABAQUS finite element software. Also modal analysis was performed to calculate the natural frequencies of each model. In the
present study, infinite boundaries were applied in order to simulate free field condition and appropriate contact elements were used to model the slip and separation phenomena between foundation and soil elements. To do so, finite element direct models were developed. Cone model, as one of the approximate methods that considers SFSI with practical engineering precision was verified and then applied in the series of simulations. An assessment procedure was applied to check the accuracy of Cone model as an approximate method in comparison with direct method. Structural responses including lateral deformation, drift, rotation and shear force distribution were studied for all cases including fixed-base, cone model and SFSI direct models. Modal analysis implies that SFSI can reduce the natural frequencies of the building. The results show that shallow foundation size, due to the interaction between soil, foundation and structure, influences the dynamic characteristics and seismic response of building. As a result, engineers should carefully consider these parameters to ensure the safety and economic seismic design. Cone Model with an appropriate engineering precision, functionality and high analysis speed is capable of assessing dynamic stiffness of soil due to the soil-foundation-structure interaction phenomena.