1.1 Principles of Base Isolation

The philosophy of base isolation of structures, generally using flexible mountings and mechanical energy dissipating devices, is reviewed. Applications of the approach to buildings, bridges, nuclear power plants, equipment and structures rocking on their foundations are described. Where possible, recommended code provisions and design rules are given. The characteristics of the mechanical energy dissipating devices developed to date are discussed and material specification provisions presented. The requirements for construction of base isolated structures and for maintenance of the devices are given. Finally, recommendations are made on matters for future research. The authors comprise a working group set up by the Management Committee of the New Zealand National Society for Earthquake Engineering to prepare recommendations for the design and construction of base isolated structures 3 suitable for the guidance of designers and approving authorities