Response of Curved Surface Sliders under bidirectional displacement orbits

The dynamic performance of Curved Surface Sliders (CSS) used in base isolation is affected from the generation of heat at the sliding surface occurring at high forces and speeds, and the consequent temperature rise that promotes the degradation of the coefficient of friction. The study presents a numerical investigation of the heating effect in a typical Curved Surface Slider. A 3D finite element thermal-mechanical model of the CSS is formulated, and numerical analyses are performed considering either unidirectional and bidirectional displacement-controlled orbits to investigate the temperature growth inside the bearing and the changes in the mechanical response of the device. A recursive algorithm is used to adjust at each iteration step the coefficient of friction based on the calculated temperature. The results demonstrate the fundamental importance of accounting for the temperature growth for a correct determination of the response of the Curved Surface Slider, and point to the inability of unidirectional trajectories performed in the tests regulated in the current standards to reproduce the temperature rises that may possibly occur under bidirectional orbits during real earthquakes.