Abstract: This paper presents a method for analyzing both linear and nonlinear seismic responses of multi-storeyed buildings composed of nonorthogonal structural members under the action of bi-directional horizontal earthquake waves. Different kinds of restoring force model are used. An efficient computer programme for the computation of nonlinear seismic response of the structure was worked out. In order to illustrate the application of this method, an example of a ten-storeyed building of such sort is given.

Key words: persistence, predator-prey system, nonperiodic