We can consider the fixity and model the superstructure considering the fixed support condition.
In actual construction, there will be a moment transfer from the superstructure to the foundation.
Further, consideration of the pin support at the foundation level increases the stiffness upper level or it can be stated as consideration of less stiffness near the foundation level. It creates the zero bending moment at the foundation level and only axial loads are transferred to the foundation.
When the foundation is not model together with the superstructure, pin supports are considered at the foundation level.
But it is not a must always to consider this effect.Įspecially for high rise buildings and when there are varied ground conditions, it is advisable to consider the effect of the foundation on the superstructure.įurther, the following can be highlighted related to the foundations modeling. When there are no out of plane actions, or if we need the membrane action, this element is useful.įoundation Modeling Techniques used in Structural AnalysisĬonsideration of the foundation and superstructure interaction is very important for some of the structures.
Membranes: When we need membrane action, we used these types of elements.
Plate Elements: Plate element is used to models the thicker element like pile caps.
Further, out of plane action is considered in this element.
Shell Elements: Thinner elements such as slabs, shear walls, etc are modeled using shell elements.
Frame Elements: Beams and columns are modeled with frame elements mainly.
The idealization of the actual structure in the most difficult part of the structural analysis. After finalizing the load on the structure, structural analysis is carried out to find the forces such as bending moments, shear forces, torsional moments, etc.