History of Seismic Isolation

History of Seismic Isolation goes long back. People have been using seismic isolation in one form or another for long time. Evidence found proves that Greeks have been implementing this concept in their structures to make flexible rocking columns which used to isolate the upper structure from ground motions.
Seismic isolation in modern times may be claimed to be started by John Milne, a British Scientist, who was professor of mining engineering at the Imperial College of Engineering in Tokyo from 1875-1895.In 1885, he built a base isolated wood house which was founded on piles. The heads of the piles incorporated balls made of cast-iron plates with saucer like edges. Structure was modified many times to finally perform adequately under real earthquakes. Japan and New Zealand was ahead in implementing this concept. In 1909, J. A. Calantarients filed a patent for lubricated free joints on a layer of fine material. System behaved like an isolation system. In 1969, first application of rubber isolated bearings was implemented in 3-story reinforced concrete elementary school building. It was a simple rubber bearing without any reinforcing steel shims. School building was later demolished due to high bulging of rubber.
1980s can be considered the decade when seismic gain popularity all around world and many structures around the world were built using seismic isolation. Japan, by that time, had implemented many building projects with isolation concepts. Significant research was devoted to this topic and many initiatives around the world were taken by government agencies and private sector to prepare the framework for development of regulations and guidelines for seismic isolation of structures. No of buildings in Japan constructed using seismic isolation increased exponentially after 1995 Kobe earthquake.
France and South Africa had already successfully implemented seismic isolation concept to their Pressurized Water Reactors (PWRs) during 1978-1984. Each of the four units at Cruas in France was isolated using 1,800 neoprene pads(500x500x65 mm). A modified isolator design was used for regions with higher seismicity; where flat sliders are installed in between top of pads and upper mat. Flat sliders used a lead-bronze alloy lower plate and a polished stainless steel upper plate. Two unit plants in Koeberg, South Africa, with a SSE of 0.3g, were isolated using this design, where total of 2000 neoprene pads (700x700x100 mm) were used. A similar design was proposed to be implemented for Karun River plant in Iran whose construction was stopped in 1978
First application of seismic isolation of in USA was seismic isolation of the Foothills Community Law and Justice Center(1982-1985). Acceptance of seismic isolation in US was rather slow; however, it gained popularity after 1989 Loma-prieta earthquake and many new and existing structures were isolated in 1990s.
Isolators used for first few applications were high damping rubber bearings which was followed by elastomeric bearing and lead-rubber bearing. Sliding bearings gain popularity in 1990s and structures now a days are isolated using primarily Elastomeric, Lead-rubber, and Friction pendulum family of bearings(sliding).

Four seismically isolation nuclear power plant units in Cruas, France (Forni et. al., 2011)