A Hertz contact model with non-linear damping for pounding simulation

This paper investigates the cogency of various impact models in capturing the seismic pounding response of adjacent structures. The analytical models considered include the contact force-based linear spring, Kelvin and Hertz models, and the restitution-based stereomechanical approach. In addition, a contact model based on the Hertz law and using a non-linear hysteresis damper (Hertzdamp model) is also introduced for pounding simulation. Simple analytical approaches are presented to determine the impact sti ness parameters of the various contact models. Parameter studies are performed using two degreeof-freedom linear oscillators to determine the e ects of impact modelling strategy, system period ratio, peak ground acceleration (PGA) and energy loss during impact on the system responses. A suite of 27 ground motion records from 13 di erent earthquakes is used in the analysis. The results indicate that the system displacements from the stereomechanical, Kelvin and Hertzdamp models are similar for a given coe cient of restitution, despite using di erent impact methodologies. Pounding increases the responses of the sti er system, especially for highly out-of-phase systems. Energy loss during impact is more signi cant at higher levels of PGA. Based on the ndings, the Hertz model provides adequate results at low PGA levels, and the Hertzdamp model is recommended at moderate and high PGA levels. Copyright ? 2006 John Wiley & Sons, Ltd.