ESDU 81036 provides estimates of frequency@ mode shape@ generalised mass and generalised stiffness for the undamped natural modes of vibration of core buildings. The data are particularly applicable in estimating the response of buildings to wind or earthquake loading. Shear effects in the core and rotatory inertia of the floors are included in the analysis@ and the foundations are modelled by an equivalent rotational spring. By suitable choice of parameters@ the method may allow other cantilever-type structures such as chimneys or tall lattice towers to be investigated. A computer program of the method is provided as ESDUpac A8136.