Effect of the Stick-Slip Phenomenon on the Sliding Response of Objects Subjected to Pulse Excitation

The response analysis of sliding objects and structures subjected to ground excitation is most often performed using Newmark's rigid sliding block with Coulomb friction. This simplified sliding model has been shown to sometimes result in poor predictions of sliding displacement. In an effort to improve sliding response predictions, this paper introduces a model that relaxes the rigidity constraint of the Newmark model and takes into account velocity-dependence of the friction force using a Stribeck friction model. It is shown that the flexibility of the support system in conjunction with velocity-dependent friction at low velocities can result in intermittent stick-slip phases during sliding. A dimensional analysis approach is taken to expose the underlying physical similarities in the sliding problem and to compare the results of the stick-slip model with conventional sliding models, including Newmark's rigid-block model and coupled sliding models that are not capable of capturing the stick-slip phenomenon. It is demonstrated that implementation of simplified sliding models may result in underestimation of the sliding response. (C) 2016 American Society of Civil Engineers.