Three-Dimensional Analysis of Tier Buildings

Three-dimensional analysis of tier buildings using a digital computer is feasible and perhaps mandatory in some cases. It is no longer necessary to simplify the problem by resorting to the notion of analyzing the building as a system of parallel and perpendicular plane frames. Errors inherent in the two-dimensional approach may be significant, whereas the three-dimensional analysis contains no theoretical discrepancies. The analytical model of the structure is examined in detail, and individual member stiffnesses are enumerated. Pertinent geometric transformations for displacements, actions, and stiffnesses are also formulated. The stiffness method of solution is described, followed by a brief outline of the computer program. Results for an example 20-story building show that the effect of axial strains in columns is substantial, whereas the influence of torsional rigidities is small.