Dynamics of Tier Buildings

The dynamic response of multi-story (tier) buildings to wind gusts, mild blast loading, and moderate earthquakes may be calculated using linear theory. A three-dimensional analytical model is required to simulate the stiffness and mass properties of a tall building containing horizontal diaphragms at all framing levels. Equations of motion for story displacements are formulated using the stiffness method and are solved by a specialized form of normal mode theory. These techniques are incorporated into a computer program for the dynamic analysis of tier buildings. A hypothetical 20-story building is analyzed to determine its vibrational characteristics as well as its response to a severe wind gust and a specified ground acceleration. The effects of modal truncation and axial strains in columns are also studied, and the results show that neglecting the latter may have serious consequences in dynamic analysis.