ABSTRACT
In the analysis of structures by computer, using the displacement method, the coordinates at the nodes typically represent displacement components in the directions of one set of global axes. It is, however, sometimes necessary to express the boundary conditions at a node as prescribed displacements in directions inclined to the global axes. The analysis of structures by the displacement method requires the solution of the equilibrium equations. The solution must satisfy the displacement boundary conditions. Large structures are commonly analyzed by computer and, when possible, advantage is taken of symmetry so as to reduce the effort needed in data preparation and in the interpretation of the results. When a structure has one or more planes of symmetry it is possible to perform the analysis on one-half, one-quarter or an even smaller part of the structure, provided that appropriate boundary conditions are applied at the nodes on the planes of symmetry.
