Numerical modelling of sliding isolators incorporating self-heating effects

As known, the frictional behavior of steel-PTFE interfaces under seismic excitation is mainly influenced by a combination of sliding velocity, contact pressure and surface temperature. However, the calibration of specified relationships among these factors and the friction coefficient is independently conducted from each other starting from experimental data. The aim of this work, through the use of a simplified thermodynamic model, is to highlight how the temperature affects these relationships, and to propose a methodology for obtaining friction-velocity curves excluding the thermal effects. This leads to a reinterpretation of the experimental results already available in the literature, showing that the friction-velocity law may be well represented by a logarithmic expression, rather than an exponential asymptotic one, accordingly to the recent models proposed in the literature. Finally, in order to evaluate the influence of this correction, Non-Linear Dynamic Analyses (NLDAs) are carried on PTFE sliding isolators having different curvature radii, considering a set of 467 Ground Motions (GMs).