Bouc-Wen-type models with stiffness degradation: thermodynamic analysis and applications

TL;DR

This paper provides a thermodynamic framework for Bouc-Wen models with degradation, introducing new rules for stiffness degradation and analyzing their energetic properties for improved modeling accuracy.

Contribution

It develops a thermodynamic analysis of Bouc-Wen models with degradation, proposing new stiffness degradation rules and linking them to endochronic plasticity theory.

Findings

Formulation of Bouc-Wen models with damage without plastic strains

Introduction of an energetic definition of dissipated energy in these models

Proposal of improved and new stiffness degradation rules

Abstract

In this paper, a thermodynamic analysis of Bouc-Wen models endowed with both strength and stiffness degradation is provided. It is based on the relationship between the flow rules of these models and those of the endochronic plasticity theory with damage, discussed in a companion paper (Erlicher and Point, 2008). Using the theoretical framework of that extended endochronic theory, it is shown that an elastic Bouc-Wen model with damage, i.e. without plastic strains, can be formulated. Moreover, a proper definition of the dissipated energy of these Bouc-Wen models with degradation is given and some thermodynamic constraints on the parameters defining the models behavior are emphasized and discussed. In particular, some properties of the energetic linear stiffness degradation rule as well as the so-called pivot rule, well-known in the seismic engineering field, are illustrated and commented upon. An improved energetic stiffness degradation rule and a new stiffness degradation rule are proposed.