NUMERICAL INVESTIGATION OF CURVED SURFACE SLIDERS UNDER BIDIRECTIONAL ORBITS

The study moves from the current debate about the suitability of the unidirectional tests regulated in the standards, and aims at investigating the effect of the displacement trajectory on the evaluation of seismic isolators. A 3D finite  element  thermal-mechanical  model  of  a  Curved Surface Sliders is formulated, and numerical analyses are performed  considering  unidirectional  and  bidirectional  displacement-controlled orbits. The temperature rise at the sliding surface is calculated from  the  software  and  used  to adjust at each iteration step the coefficient of friction of the bearing. The results of the analyses examining  different  orbits  are  compared  in  terms  of  maximum  shear  force, dissipated energy and temperature rise on the surface of the thermoplastic pad. The conclusions point to the fact that the unidirectional  tests  provide a conservative evaluation of the bearing performance, but are not suitable for determining the bearing properties that  are  needed for accurate nonlinear   response   history   analyses.  Furthermore,   unidirectional   tests   tend   to   underestimate   the  temperature  rise  induced  from bidirectional  trajectories.

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Virginio Quaglini, Emanuele Gandelli, Paolo Dubini