2. There are two methods to determine S and R. They are elastic method and plastic method. Discuss the conditions under which elastic or plastic methods are suitable.

For elastic-plastic analysis the procedure is similar and consists initially of assembling the stiffness matrix of the structure using the stiffness submatrices for each member, allowing for instability effects. For member 12, considering the forces and displacements shown in Figure 12.12, this is given by

answer:

my guess it 8 i'm probably wrong