الفهرس 
CHAPTER (1): INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Seismic response of structures resting on the ground is influenced by the
subsoil properties, and this response significantly differs from the fixed-base condition. Also, the existence of the structure influences the motion of the soil beneath the structure. The mutual effect between the ground, and the structure is called soil-structure interaction, and this phenomenon decreases the natural frequency of the soil-structure system, and increases its damping ratio in comparison with the
fixed-base system. The objective of this study is to investigate the effect of soil-structure interaction on the seismic response of multi-storey structures, so three-dimensional numerical models are developed using ABAQUS software to carry out time-history analyses to study the behavior of soil-structure systems. Structures are analyzed under two different base conditions, namely fixed-base condition, and flexible-base condition. In this research, effects of different parameters on the structural seismic
response considering soil-structure interaction are investigated in terms of
fundamental time period, and base shear forces. To assess the effect of subsoil type, three soil types have been adopted representing classes B, C, and D according to ECP 201, 2012, and their results are compared to those of the fixed-base model. To evaluate the influence of structure height “represented by number of stories”, five storey, eight-storey, and ten-storey buildings have been analyzed. To investigate the effect of ground motion type, three ground motions, including El Centro, 1940 earthquake, Northridge, 1994 earthquake, and Kobe, 1995 earthquake have been used as the input motion for all analyzed models. Also, moment resisting frames, shear walls, and dual system have been used for the ten-storey building to study the effect
of the lateral load resisting system type on the seismic response of structures. To evaluate the influence of foundation dimensions, raft foundations with dimensions of 12, 13, 14, and 15 meters in both length and width have been used to support the ten storey moment resisting frames. To inspect the influence of foundation embedment, raft foundation with no embedment, 1 m, 2 m, and 3 m embedment depths have been used to support the ten-storey moment resisting frames. Modelling process involved the determination of soil parameters to be employed in the finite element model. Nonlinear stress-strain behavior of the soil was represented by Mohr–Coulomb model which is an elastic-perfectly plastic model used by many researchers to simulate nonlinear behavior of soils in soil-structure interaction problems. Direct method of soil-structure interaction modelling has been employed in this study by simulating the structure, and the soil in the same model to get more accurate and reasonable results. Finally, soil-structure interaction should be considered in the analysis process
of multi-storey structures to provide safe and cost-effective design against seismic loads, some conclusions have been derived to illustrate the effects of the studied parameters on soil-structure interaction, and to demonstrate the importance of this
phenomenon in structural analysis. These conclusions can be used as a useful guide during dealing with soil-structure interaction problems.