Response of Structures to Horizontal-Vertical Earthquakes

In the present work, the responses of a class of hysteretically nonlinear structures subjected to the combined horizontal and vertical random ground accelerations are studied. A massless elasto-plastic column, supporting a concentrated mass at the top and rigidly clamped to the ground is used as the working structural model. The hysteretic restoring force of the structure is assumed to follow the relationship proposed by Wen. The method of nonstationary equivalent linearization is used and the time dependent parameters of the equivalent linear system in terms of response moments are obtained. The earthquake excitations are modeled by segments of nonstationary Gaussian white noise and filtered white noise processes.