Modified linear viscoelastic model of earthquake-induced structural pounding

In recent times, earthquake-induced structural pounding has been intensively studied through the use of different impact force models. The numerical results obtained from the previous studies indicate that the linear viscoelastic model is relatively simple and accurate in modeling pounding-involved behavior of structures during earthquakes. The only shortcoming of the model is a negative value of the pounding force occurring just before separation, which has no physical explanation. The aim of the present paper is to verify the effectiveness of the modified linear viscoelastic model, in which the damping term is activated only during the approach period of collision, therefore overcoming this disadvantage. First, the analytical formula between the impact damping ratio and the coefficient of restitution is reassessed in order to satisfy the relation between the post-impact and the prior-impact relative velocities. Then, the performance of the model is checked in a number of comparative analyses, including numerical simulation of pounding-involved response, as well as comparison with the results of the impact experiment and shaking table experiments concerning pounding between two steel towers excited by harmonic waves. The final outcome of this study demonstrates that the results obtained through the modified linear viscoelastic model without the tension force are comparably similar to those found by using the linear viscoelastic model.