Recently I happen to read a document on stiffness analysis procedure.

This is the summary of steps to be followed in performing a stiffness analysis :

1. Determine the needed displacement unknowns at the nodes/joints and label them d1, d2, …, dn in sequence where n = the number of displacement unknowns or degrees of freedom.

2. Modify the structure such that it is kinematically determinate or restrained, i.e., the identified displacements in step 1 all equal zero.

3. Calculate the member fixed-end forces in this kinematically restrained state at the nodes/joints of the restrained structure due to the member applied loads. Tables of member-end forces due to member loads for the kinematically restrained members are available later in these notes. The member-end forces are vectorially added at the nodes/joints to produce the equivalent fixed-end structure forces, which are labeled Pfi for i = 1, 2, …, n later in the notes.

4. Introduce a unit displacement at each displacement degree of freedom identified in step 1 one at a time with all others equal to zero and without any loading on the structure, i.e., di = 1 with d1, …, di-1, di+1, …, dn = 0 for i = 1, 2, …, n.
Sketch the displaced structure for each of these cases. Determine the member-end forces introduced as result of each unit displacement for the kinematically restrained structure. These member-end forces define the member-end stiffness coefficients, i.e., forces per unit displacement. The member-end stiffness coefficients are vectorially added at the nodes/joints to produce the structure stiffness coefficients, which are labeled Sij for i = 1, 2, …, n and j = 1, 2, …, n.

5. Eliminate the error introduced in step 3 to permit the displacement at the nodes/joints. This is accomplished by applying the negative of the forces calculated in step 3 and defines the kinematically released structure.

6. Calculate the unknown node/ joint displacements.

7. Calculate the member-end forces.

Can the CAESAR Design engineers in COADE tell me whether the CAESAR uses the above technique in analysing the model ?