Formulation of the element matrices and vectors for elasticity problem > Incorporation of boundary conditions

This method is very similar with the penalty method. The spring (elastic support) can be added to any structural degree of freedom. Each spring adds a prescribed value to the leading diagonal of the stiffness matrix in the row in which the prescribed value is required. Elastic supports, or springs, are defined by entering spring constants in the X and/or Y directions. The spring constant is defined as the force or moment that will cause a unit displacement in the relevant direction. A very stiff spring (a large value, say 1020) a zero displacement is enforced.