1. FOUNDATION ON ELASTIC SUBSOIL
ZAHRA SHARIF KHODAEI

2. INTRODUCTION

3. INTRODUCTION

4. PROCEDURE FOR FEM Divide the structure into nodes and elements
Find the joint forces and initial displacements
Calculate the end forces for each element
Assemble the global joint forces (localize)
Calculate the local stiffness matrix for each element
Transform the local stiffness matrix to global stiffness matrix
Localize to obtain the overall stiffness matrix
Solve: Ku = f for the displacements u.
Compute the local displacements for each member
Calculate the inner forces from fl = Kl ul

5. EXAMPLE

6. MESH
SIGN CONVENTION Y X

7. Something about CAL The command to solve a grid on elastic subsoil is:
GRID km E=? G=? I=? J=? L=? CW=? CP=? B=? K=?
Where:
km … element stiffness matrix
E … modulus of elasticity
G … shear modulus
I … moment of inertia
J … torsional moment of inertia
L … length of the element
CW… Winkler’s constant C1
CP… Pasternak’s constant C2
B … width of the cross section
K = 1 … takes into account the neighborhood of the foundation

8. RESULTS:
INTERNAL FORCES IN THE MEMBERS

9. DEFLECTIONS:

10. BENDING MOMENTS:

12. COMPARISON