Fundamentals of the Stiffness Method
The stiffness method (also known as the displacement method) is the primary method used in matrix analysis of structures. One of its advantages over the flexibility method is that it is conducive to computer programming. Once the analytical model of a structure has been defined, no further engineering decisions are required in the stiffness method in order to carry out the analysis. In this respect it differs from the flexibility method, although the two approaches have similar mathematical forms. In the flexibility method the unknown quantities are redundant actions that must be arbitrarily chosen; but in the stiffness method the unknowns are the joint displacements in the structure, which are automatically specified. Thus, in the stiffness method the number of unknowns to be calculated is the same as the degree of kinematic indeterminacy of the structure.
KeywordsStiffness Matrix Flexural Rigidity Joint Displacement Plane Frame Plane Truss
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