Base Isolation Technology for Rocking Statues. A Simplified Design Procedure

When subjected to earthquakes, some objects or structures can behave like rocking rigid bodies. Statues, ancient columns, computer servers and electrical equipment are frequently included in this category. Conservation of these objects can be a crucial task, due to their tangible and, at times, intangible value as well; base isolation technology has been proven to be a viable option for this purpose. The dynamic model of a rocking rigid block placed on a base isolation device is summarized here. Then, a displacement-based procedure to design this type of protection system for rigid rocking bodies is proposed, and the main steps are illustrated. The procedure aims to determine the characteristics of the isolator to prevent initiation of rocking motion during the design earthquake. The proposed procedure is successively validated by examining the dynamic response of the system to a suite of a spectrum compatible accelerograms. To this end, the minimum analytical period of the isolator that prevents rocking motion (identified using the proposed procedure) is compared with that obtained using time history analysis. The results highlighted the sensitivity of the system to the input records. Successively, a suite of accelerograms scaled to match the design spectrum at the analytical period of the isolator is used for validation. In this case, the efficiency of the proposed design method is demonstrated. The presented displacement-based procedure appears applicable for the preliminary design of the isolators, and the no rocking approach seems particularly suitable for small size objects.