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

Thisstudy investigates the main reason for the durability of traditional Japanesestructures in active seismic zones using two types of natural seismic baseisolation (NSBI) devices derived from these structures. The modelling of the interaction between thestructure and foundation of these structures shows that part of the interactionhas a particular earthquake isolation characteristic; thus, it has thepotential to be used as an effective seismic isolation device. In thetraditional Japanese buildings, the contact between the foundations and thestructure were not anchored; thus, there were either two frictional slidinginterfaces between timber and stone, stone and stone, or only one interfacebetween timber and stone. The study investigates the feasibility of theapplication of a structural-mathematical model to the structure-foundationinteraction model of traditional Japanese structures using the NSBI device withsingle and two sliding interfaces. Theanalysis has revealed that the NSBI devices have reduced the maximumacceleration response by an average 60% when compared to a conventionalstructure under earthquake excitation. A comparison of the earthquake acceleration performance of single anddual interface NSBI devices clearly shows that the single friction interfaceNSBI device is 4% more efficient than the two-sliding interface NSBI devices. Thisinvestigation has revealed that the structure-foundation contact part of thetraditional Japanese buildings containing one or two sliding interfaces allowthe superstructure to move, thus reducing the effect of seismic forces on thesuperstructure. This contact part, namely the NSBI device, acts as a passivecontrol system, and can be the main reason behind the durability of thesestructures at one of the most active seismic zones in the world since theancient times.