In the previous post we have learned about rigid beam
method for raft foundation analysis. In this post we will learn
overall idea of all methods of analysis. The methods that are available to
analyze a raft foundationare:
a. Rigid beam methods
b. Elastic or non-rigid method
In rigid beam method of analysis as discussed in early
posts is a simple static method. There have some assumptions that make this
method less appropriate for analyzing rafts. We will not discuss much about
this method. We will have only summary of these method. In this method mat is
considered as true rigid body which is the main limitation and this method is
not supposed to model mat as in actual condition. With this limitation this
method was used through the decades as it is simple and more refined method of
modeling mat to represent actual situation was not available.
Now with the help of electric calculation we can model
mat nearly actual condition and this method is elastic or non rigid method. In
this post we will learn only overall idea of non-rigid method of mat analysis.
Non-rigid method involves followings:
a. Using elastic theory-ready made closed formed
solutions
b. Method of discrete element, dividing mat into some
elements along grids
c. Beams or plates in elastic foundations
d. Beams or plates in elastic continuum
Of these, the method of discrete element includes:
1. Finite difference(FDM) method
2. Finite grid(FGM) method
3. Finite element(FEM)method
Of these, finite element method of analysis is the finest
way to model and analyze mat. In this method mat are assumed as plate
supporting on elastic foundation.
