Non-Bouc Degrading Hysteresis Model for Nonlinear Dynamic Procedure Seismic Design

Exhaustive nonlinear dynamic procedure (NDP) analysis requires a degrading hysteresis model expressed as a differential equation. The classical form of differential equation hysteresis model is the Bouc-Wen model which is smoothly varying, and most other such models developed subsequently have the BoucWen model as the core. In this paper an alternative differential equation endochronic plasticity model is presented. A computational model for the system identification of the parameters is also presented and the resulting model is applied to the experimental results of lateral cyclic in-plane tests on 20 retrofitted masonry walls. Data and analysis of the identification procedure results are presented as well as sample plots of the calculated versus experimental hysteresis loops. It is found that the model yields generally acceptable agreement with the experimental results and that the proposed model resulted in a stable and inexpensive parameter identification process.