Abstract:
In design practice, dynamic structural analysis is carried out with base of structure considered as fixed; this means that foundation is placed on rock like soil material. While conducting this type of analyses the role of foundation and soil behavior is totally neglected. The actions in members and loads transferred at foundation level obtained in this manner do not depict the true structural behavior.
FEM analysis are proposed where both superstructure and foundation soil are coupled together. This type of FEM analysis is quite complicated and expensive for design environments. A simplified model is required to depict dynamic response of structures with foundations based on flexible soils.
The primary purpose of this research is to compare the superstructure dynamic responses of structural systems with fixed base to that of simple soil model base. The selected simple soil model is to be suitable for use in a design environment to give more realistic results. For this purpose building models are idealized with various heights and structural systems in both 2D and 3D space. These models are then provided with visco-elastic supports representing 3 soil bearing capacities and the analysis results are compared to that of fixed supports models.
The results indicate that fixed support system underestimates natural time period of the structures. Dynamic behavior and force response of visco-elastic support is different from fixed support model. Fixed support models result in over designed base columns and under designed beams.
