EQUIVALENT LINEARIZATION OF GENERALLY PINCHING HYSTERETIC, DEGRADING SYSTEMS

Many types of structural systems that undergo cycles of inelastic defo rmation under severe natural hazard loadings exhibit 'pinching' of hys teresis loops. In this paper, a generally pinching hysteretic restorin g force model-an extension of the Bouc-Wen differential hysteresis mod el-is used in stochastic equivalent linearization of single-degree-of- freedom structural systems. The severity and rate of pinching are cont rolled by the hysteretic energy dissipation and the pinching level can be specified to match experimental data. Under white noise excitation s, estimates of reponse statistics from linearization are shown to com pare favourably with those from Monte Carlo simulation. Numerical stud ies on the sensitivity of the accuracy of response statistics obtained by linearization to changes in the hysteresis parameters showed that, for a range of practical cases, the linearization method can be used in lieu of simulation and that, in low-frequency systems, some hystere sis parameters may be set to a constant value a priori to reduce the n umber of model parameters that needs to be estimated or identified, an d to simplify further random vibration analysis and/or performance eva luation studies.