Date of Award


Degree Type


Degree Name

Master of Engineering Science


Civil and Environmental Engineering


Dr. Hesham El Naggar


This thesis is dedicated to investigate the seismic performance of moment-resisting frame steel buildings with multiple underground stories resting on shallow foundations and to evaluate the current common modeling assumption of analyzing the seismic response of these buildings fixed at the ground surface. The role of the Soil-Structure Interaction (SSI) phenomenon in the seismic design of buildings was extensively reviewed from the structural and geotechnical perspective. The rocking behavior of shallow foundations can greatly affect the seismic response of the supported structures. Thus, one of the main objectives of this thesis is to develop and validate a practical and reliable modeling approach suitable for analyzing the cyclic response of 3D shallow foundations with special attention to their moment-rotation behavior. A parametric study that involved evaluating the nonlinear seismic response of five, ten and fifteen story moment-resisting frame steel buildings resting on a flexible ground surface, and buildings having one, three and five underground stories was performed. It was found that SSI can greatly affect the seismic performance of buildings in terms of the seismic storey shear and moment demand, and the deformations of their structural components. Although most building codes postulate that SSI effects generally decrease the force demand on buildings but increase the deformation demand, it was found that, for some of the cases considered, SSI effects increased both the force and deformation demand on the buildings. iii The SSI effects generally depend on the stiffness of the foundation and the number of underground stories. SSI effects are significant for soft soil conditions and negligible for stiff soil conditions. It was also found that SSI effects are significant for buildings resting on flexible ground surface with no underground stories, and gradually decrease with the increase of the number of underground stories.



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