Sliding pendulum isolators without secretes

Abstract

Over the last decades, anti-seismic devices have gained increasing interest in the civil engineering field. The introduction of the base isolation system has led to a new concept in the construction panorama in terms of human life safety, a new way of thinking on new constructions, improvement and retrofitting on existent structures. Therefore, rubber and friction isolators have been deeply investigated to hence performances and predict dynamic behaviour during an earthquake. While the response of the former is characterised by the composition of the elastomeric compound, the latter features special materials able to dissipate energy by moving on smooth surfaces. This paper focuses on friction pendulum devices and addresses its attention on the behaviour of sliding materials. It is well-known that stick-slip phenomenon occurs when friction excitation is present and, in the anti-seismic field is important to reduce it and have a well-representative mathematical law able to describe it. Therefore, Hirun International after performing several treatments of the sliding materials has set up a special processing to guarantee a stable response of the HI-M material used on pendulum devices. The paper, after a brief presentation of the special sliding material, shows a comparison between the material with and without the treatment in terms of the force-displacement law. The paper also analyses in detail the cinematic behaviour of the sliding pendulum with one or two main sliding surfaces, with and without central articulation and determines the stress distribution in the sliding surfaces for the different cases.