Seismic base isolation

Base Isolation is believed to be the most powerful tool of the earthquake engineering pertaining to the passive structural vibration control technologies. It is meant to enable a building or non-building structure to survive a potentially devastating seismic impact through a proper initial design or subsequent modifications. In some cases, application of Base Isolation can raise both a structure's seismic performance and its seismic sustainability considerably.

Base Isolation, also known as Seismic or Base Isolation System, is a collection of structural elements which should substantially decouple a superstructure from its substructure resting on a shaking ground thus protecting a building or non-building structure's integrity (see, e.g., the concurrent shake table testing video on Earthquake Protector).

Base Isolation System consists of Isolation Units with or without Isolation Components, where:

1. Isolation Units are the basic elements of Base Isolation System which are intended to provide the mentioned decoupling effect.

2. Isolation Components are the connections between Isolation Units and their parts having no decoupling effect of their own.

By their response to an earthquake impact, all Isolation Units may be divided into two basic categories: Shear Units [1] and Sliding Units [2].

The first evidence of earthquake protection by using the principle of Base Isolation was discovered in Pasargadae (Persian: پاسارگاد), a city in ancient Persia, now Iran: it goes back to VI century BC.

This technology can be used both for new structural design [3] and seismic retrofit of existing structures.

External Links

• LBRtest: Lead Rubber Bearing being tested at the UCSD Caltrans-SRMD facility
• Testing of a New Line of Seismic Base Isolators called Earthquake Protector
• Seismic Isolation Projects in Japan