The modeling of deteriorating hysteretic behavior is becoming increasingly
important, especially in the context of seismic analysis and design. This p
aper presents the development of a versatile smooth hysteretic model based
on internal variables, with stiffness and strength deterioration and with p
inching characteristics. The theoretical background, development, and imple
mentation of the model are discussed. Examples are shown to illustrate the
features of the model. Many inelastic constitutive models in popular use ha
ve been developed independently of each other based on different behavioral
, physical, or mathematical motivations. This paper attempts to unify the c
oncepts underlying such models. Such a holistic understanding is essential
to realize limitations in application of inelastic models and to extend 1D
models to 3D models featuring interaction between various stress resultants
.