Computer-Oriented Direct Stiffness Method
In the preceding chapter the stiffness method was developed initially by superposition of actions for the free displacement coordinates (Sec. 3.2). Then the method was formalized and extended in Sec. 3.6 using the compatibility matrix CMJ and the virtual work concept. With this second approach the complete joint stiffness matrix S, (for both free and restrained displacements) was assembled by the triple matrix multiplication given as Eq. (3–32). While the formal version is enlightening and well organized, it involves a large and sparse compatibility matrix containing terms that are not easy to evaluate correctly. Neither the generation of this matrix nor the multiplication process for assembly would be suitable for computer programming. A better methodology consists of drawing ideas from both approaches and adding a few computer-oriented techniques to evolve what is known as the direct stiffness method.
KeywordsStiffness Matrix Direction Cosine Continuous Beam Structural Axis Joint Displacement
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