Abstract
In the statistical analysis of dynamic behaviour of elastic-plastic structures, Equivalent Linearization Method is very useful and practical because of the simplicity of its theory. But the method loses the accuracy as the structure becomes to show large deflection and strong non-linearity. In this paper, the cause of the loss of the accuracy is examined and the method is modified to be applicable to the analysis of strong non-linear structures. The cause of the loss of the accuracy is assumed to be the loss of the stability of the displacement hysteresis which is attended with an unstable fluctuation of the center of oscillation. The shift of the center of oscillation is calculated based on the assumption that the running average of the external force in one cycle is not zero and the work done by this average force is transfered into the added plastic deformation in one way. Non-stationary RMS response to the stationary and non-stationary white noise is calculated by digital simulation and by author's method. It is shown that both results coinside fairly well each other and that a little diffierence of the spectral characteristics of the excitation in the long period region causes no small difference of the displacement response.
