The Contribution of Natural Seismic Base Isolation on the Durability of Traditional Japanese Structures

Abstract

This study investigates the main reason for the durability of traditional Japanese structures in active seismic zones using two types of natural seismic base isolation (NSBI) devices derived from these structures. The modelling of the interaction between the structure and foundation of these structures shows that part of the interaction has a particular earthquake isolation characteristic; thus, it has the potential to be used as an effective seismic isolation device. In the traditional Japanese buildings, the contact between the foundations and the structurewere not anchored; thus, there were either two frictional sliding interfaces between timber and stone, stone and stone, or only one interface between timber and stone. The study investigates the feasibility of the application of a structural-mathematical model to the structure-foundation interaction model of traditional Japanese structures using theNSBI devicewith single and two sliding interfaces. The analysis has revealed that the NSBI devices have reduced the maximum acceleration response by an average 60% when compared to a conventional structure under earthquake excitation. A comparison of the earthquake acceleration performance of single and dual interface NSBI devices clearly shows that the single friction interface NSBI device is 4% more efficient than the two-sliding interface NSBI devices. This investigation has revealed that the structure-foundation contact part of the traditional Japanese buildings containing one or two sliding interfaces allow the superstructure to move, thus reducing the effect of seismic forces on the superstructure. This contact part, namely the NSBI device, acts as a passive control system, and can be the main reason behind the durability of these structures at one of the most active seismic zones in the world since the ancient times.