Thermomechanical models of flat, single and double friction pendulum bearings

Friction pendulums are relatively new and cheaper seismic isolators that is increasingly attracting the interest of both the technical and scientific communities as an alternative to the already widely adopted elastomeric ones. Even if its effectiveness has been extensively proved, many aspects concerning the behavior under seismic action still need to be clarified. One of these is the effect of the heat developed by friction during the sliding of the surfaces in contact, which could significantly influence the superficial properties of the sliding surfaces and, consequently, the overall performance of the isolating system, due to eventual recoupling of the structure with the ground shaking. The most commonly used methods to compute the temperature rises during motion are based on the solution of heat conduction problems on a semi-infinite body under intermittent heat pulses and therefore require the computation of convolution integrals. In this work a very simple alternative for the computation of the temperature changes during motion induced by frictional heating is proposed, on the basis of suitable thermo-mechanical rheological elements. The effectiveness of the modeling is then validated through the numerical simulation of some experimental tests carried out both on flat bearings and friction pendulums.