IHS ESDU Undamped natural vibration of shear buildings. 79005

ESDU 79005 gives methods for obtaining the natural frequencies, mode shapes and normal-mode generalised masses for both lateral and torsional vibration of a shear building. A shear building is a building that can be idealised to have inextensible columns and rigid floors so that no joint rotation occurs when vibrating. The data are given in graphs for a shear building with equal mass in each storey and having uniform stiffness or linearly varying stiffness with storey in the vertical direction. In that case the data relate to the first four uncoupled modes of buildings with from 4 to 60 storeys. A method of calculating the parameters for coupled vibration from the uncoupled motion parameters is given for a special class of shear building. For shear buildings that cannot be idealised to those special cases, a computer program, ESDUpac A7905 is provided. A practical worked example illustrates the use of the data.