Hysteretic Models for Deteriorating Inelastic Structures

This paper presents a plausible reformulation and extension to the Bouc-Wen hysteresis model and gives an excellent summary and comparison of various theories of deteriorating constitutive models of hysteresis. A preliminary study on the effect of using overly simple hysteresis models (e.g., the bilinear model) when actual behavior includes strength degradation, stiffness degradation, and/or pinching indicated potentially significant errors in estimates of peak response and reliability of some structural systems (Paevere and Foliente 2000). Thus, as the authors correctly stated, ‘‘such deterioration must be taken into account in the modeling and design of seismic-resistant structural systems.’’ The discussers commend the authors for putting forward a unifying concept that relates seemingly disparate deterioration models. This has many potential practical applications and will surely add to our understanding of the complex response of realistic systems under extreme dynamic loads. Not intending to downplay the paper’s significant contribution, the discussers wish to make some clarifying comments on the modeling of asymmetric yielding hysteresis, stiffness degradation, and pinching in the paper.