Assembly of Stiffness Matrix and Force Vector for Piecewise Quadratic Basis Functions

As stated in section 6.4, the procedure of assembling the element stiffness matrices and the element force vectors into the global stiffness matrix and the global force vector consists of the following two steps:

Step 1 : Expansion of the element stiffness matrix and the element force vector to the full size for every element. For element k , this is done by using the relations (6.36 - 6.37)

	where
= 0	otherwise.	(8.32a)
	where ,
= 0	otherwise.	(8.32b)

Here, [C] is the connectivity matrix.

Step 2 : Addition of the expanded matrices and the expanded vector . This is done by using equations (8.24) and (8.26). At this stage, the 2 nd term of equation (8.26) is incorporated. Thus,

	for i = 1,2,3..., , for j = 1,2,3..., ,	(8.33)
	for i = 1,2,3..., .	(8.34)