Variability of tall building response to earthquakes with changing epicentre direction

Using a 40‐storey building as an example, the structural response under the excitation of horizontal earthquake ground motion is shown to vary greatly with the direction from the building site to the epicentre. Two mathematical models are used to represent the ground motion: the stationary random process model and the evolutionary‐type non‐stationary random process model. The former model is suitable if the duration of the most intense portion of an earthquake is much longer than the fundamental natural period of the structure. The maximum standard deviations of selected structural response quantities are computed and plotted for all possible epicentre directions, and the information is believed to be useful for design purposes.